Habtamu Shebabaw Thesis - AAU Institutional Repository

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ADDIS ABABA INSTITUTE OF TECHNOLOGY (AAiT)

SCHOOL OF GRADUATE STUDIES

DEPARTMENT OF CHEMICAL ENGINEERING

FOOD ENGINEERING STREAM

Effect of Processing on Physicochemical and Antinutritional

Factors of “Anchote”(Coccinia Abyssinica) and Development of

Value Added Biscuit

A Thesis Submitted to the School of Graduate Studies of Addis Ababa

University, Institute of Technology, in Partial Fulfillment of the

Requirements for the Degree of Masters of Science in Chemical

Engineering (Food Engineering)

By

Habtamu Shebabaw

Advisor

Professor Yogesh Kumar Jha (PhD)

Addis Ababa, Ethiopia

February, 2013

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ADDIS ABABA INSTITUTE OF TECHNOLOGY (AAIT)

SCHOOL OF GRADUATE STUDIES

SCHOOL OF CHEMICAL AND BIO - ENGINEERING

Effect of Processing on Physicochemical and Antinutritional

Factors of “Anchote” and Development of Value Added Biscuit

A Thesis Submitted to the School of Graduate Studies of Addis Ababa

Institute of Technology, in Partial Fulfillment of the Requirements for the

Degree of Master of Science in Chemical Engineering

(Food Engineering Stream)

By:

Habtamu Shebabaw Kassa

Approved by the Examining Board: Signatures

Dr. Ing Berhanu_Assefa (Assoc. Professor) __________________

Chairman, Department’s Graduate Committee

Professor Yogesh Kumar Jha (PhD) __________________

Advisor

Dr. Beteley Tekola(Assit. Proffesor ) _________________

External Examiner

Dr. Eng Shimelis Admassu (Assoc. Professor) __________________

Internal Examiner

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Acknowledgements

All praises and thanks for ALMIGHTY GOD who is the entire source of all knowledge

and wisdom endowed to mankind.

I would like to express my deepest gratitude and thanks to my advisor, Prof. Dr Yogesh

Kumar Jha for the support and guidance in the manuscript writing as well as for his

encouragement, advice, and concrete support during conducting this thesis work.

I express my heartfelt gratitude to Dr. Eng. Shimelis Admassu (Assoc. Prof.) for his

suggestions, advice and being like a father to me since starting from at the time of

learning; during thesis title selection and for his motivation and support to successfully

finish this thesis paper.

I owe my genuine thanks to Ato Desta Fekadu, who support me in providing

information and materials regarding to my thesis work.

I also extend my profound gratitude to Addis Ababa University Institute of Technology

chemical engineering department for providing facilities and research fund to conduct

this research. I am also very thankful to the technical staffs of chemical engineering

department laboratories, especially, W/ro Azeb Tebebu, W/ro Tiringo Tadesse and Yosan

Teshome for providing all the necessary laboratory facilities needed for my analysis.

I would also thank the quality control and Research Service staffs of Kaliti Food Share

Company, for their valuable support in carrying out the tests as well as their advice and

comments. Also thanks to People at the Ethiopian Health and Nutrition Research Institute

(EHNRI), Jije Laboglass plc for helping in my analysis work

Lastly, I would like to thank my parents and my friends whose love, patience, and

encouragement made my present accomplishment.

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Table of contents Title Pages

Title page…………………………………...…………………………………………………...…i

Acknowledgements ................................................................................................................ iii

Table of contents ..................................................................................................................... iv

List of Figures…...…………………………………………………...………..…………vi

List of Tables…...……………………………………………………...………………..vii

List of Abbreviations ............................................................................................................... ix

List of Appendices……………………………………………….………………….……ix

Abstract .................................................................................................................................... xi

CHAPTER ONE - INTRODUCTION ................................................................................ 1

1.1 Background ............................................................................................................... 1

1.2 Statement of the problem .......................................................................................... 2

1.3 Objectives .................................................................................................................. 3

1.4 Significance of the study ........................................................................................... 4

CHAPTER TWO - LITERATURE REVIEW .................................................................. 5

2.1 Origin and Distribution of anchote............................................................................ 5

2.2 Ecology and agriculture of anchote ........................................................................... 5

2.3 Importance of anchote ............................................................................................... 7

2.4 Traditional processing of anchote ........................................................................... 10

2.4.1 Traditional ways of serving anchote…………………………………….…….12

2.5 Antinutritional factors ............................................................................................. 13

2.5.1 Antinutritional effects of phytate ...................................................................... 13

2.5.2 Antinutritional effects of tannins ...................................................................... 14

2.5.3 Antinutritional effects of oxalate ...................................................................... 15

2.5.4 Antinutritional effects of cyanide ..................................................................... 16

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2.6 Physicochemical and functional properties ............................................................. 17

2.6.1 Physicochemical properties .............................................................................. 17

2.6.2 Functional properties ........................................................................................ 18

2.7 Processing methods as a means of reducing antinutritional factors ........................ 20

2.7.1 Boiling and roasting.......................................................................................... 20

2.7.2 Fermentation ..................................................................................................... 20

CHAPTER THREE - MATERIALS AND METHODS ................................................... 23

3.1 Materials .................................................................................................................. 23

3.2 Framework of the experiment ................................................................................. 24

3.3 Processing methods ................................................................................................. 25

3.3.1 Flour preparation from raw, boiled, roasted and fermented anchote tubers ..... 25

3.3.2 Blend formulation ............................................................................................. 28

3.3.3 Processing method of biscuit made from anchote-wheat composite flour ....... 29

3.4 Analysis methods .................................................................................................... 30

3.4.1 Proximate and mineral analysis ........................................................................ 30

3.4.2 Physicochemical properties analysis ................................................................ 35

3.4.3 Functional properties analysis .......................................................................... 36

3.4.4 Antinutritional factor analysis .......................................................................... 38

3.4.5 Sensory value analysis ...................................................................................... 41

3.5 Experimental design and statistical analysis of data ............................................... 41

3.6 Techno-economic feasibility analysis………………………...…………………..41

CHAPTER FOUR - RESULTS AND DISCUSSIONS ................................................ 43

4.1 Proximate and mineral composition of anchote flour ............................................. 43

4.2 Antinutritional factors of anchote flour ................................................................... 52

4.2.1 Phytate .............................................................................................................. 52

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4.2.2 Tannin ............................................................................................................... 53

4.2.3 Oxalate .............................................................................................................. 54

4.2.4 Cyanide ............................................................................................................. 55

4.3 Physicochemical properties of anchote flour .......................................................... 56

4.4 Functional properties of anchote flour .................................................................... 59

4.5 Proximate and mineral compositions of anchote- wheat based biscuit ................... 65

4.6 Sensory qualities of anchote-wheat biscuit ............................................................. 67

CHAPTER FIVE - SUGGESTED TECHNOLOGY FOR BISCUIT PRODUCTION …… 70

5.1 Biscuit-making procedure ....................................................................................... 70

5.2Material and energy balance .................................................................................... 71

5.2.1 Material balance to prepare anchote flour ........................................................ 71

5.2.2 Material balance for anchote-wheat biscuit preparation ................................... 72

5.2.3 Energy balance during biscuit baking process ................................................. 75

5.3 Economic analysis of the study ....................................................................... 77

5.4 Equipment layout of biscuit producing plant .......................................................... 86

CHAPTER SIX - CONCLUSIONS AND RECOMMENDATIONS ........................... 87

6.1 Conclusions ............................................................................................................. 87

6.2 Recommendations ................................................................................................... 88

REFERENCE ........................................................................................................................ 90

APPENDICES ....................................................................................................................... 99

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List of Figures

Figure No. Title

Pages

Figure 2.1. Boiled anchote tubers (after peeling) 12

Figure 3.1 Anchote flour from raw anchote tuber 25

Figure 3.2 Anchote flour from boiled anchote tuber 26

Figure 3.3 Anchote flour from roasted anchote tuber 27

Figure 3.4 Anchote flour from fermented anchote tuber 28

Figure 3.5

Figure 4.1

Flow diagram for biscuit production

Samples of raw anchote tuber

30

43

Figure 4.2 Biscuit made from anchote-wheat composite flour 69

Figure 5.1 Equipment layout of biscuit producing plant

86

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List of Tables

Table No. Title Pages

Table 2.1

Table 2.2

Comparison of the main composition of anchote and some root

crops commonly grown in southern and southwestern parts of

Ethiopia

Nutritional and anti-nutritional composition of raw and

processed anchote tubers

9

11

Table 4.1 Proximate compositions of raw and processed anchote flour 49

Table 4.2 Mineral compositions of raw and processed anchote flour 52

Table 4.3 Antinutritional factors of raw and processed anchote flour 56

Table 4.4 Physicochemical properties of raw and processed anchote flour 58

Table 4.5 Functional properties raw and processed anchote flour 64

Table 4.6 Proximate composition of biscuit recipe 65

Table 4.7 Proximate composition of anchote- wheat based biscuit 66

Table 4.8 Mineral compositions of anchote-wheat based biscuits 67

Table 4.9 Sensory characteristics of anchote- wheat based biscuits 69

Table 5.1 Major equipments delivered purchasing cost 78

Table 5.2 Human resource requirement 79

Table 5.3 Cost of raw materials 80

Table 5.4 Cost of utilities 81

Table 5.5 Estimation of direct and indirect cost 82

Table 5.6 Estimation of total product cost 83

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List of Abbreviations

Amh. Amharic

ANOVA Analysis Of Variance

AOAC Association of Analytical Chemists

AWB1 10% Anchote-wheat biscuit

AWB2 20% Anchote-wheat Biscuit

AWB3 30% Anchote-wheat Biscuit

AWF

BP

Anchote Wheat Flour blend

Blend proportion

BD Bulk Density

CHO Carbohydrate

EHNRI Ethiopian Health and Nutrition Research

Institute

FAO Food and Agricultural Organization

FC Foam Capacity

FCI Fixed Capital Investment

MC Moisture Content

OAC Oil Absorption Capacity

Oro. Oromiffa

TEC Total Equipment Cost

TDC Total Direct Cost

TPC Total Product Cost

SP Swelling Power

TTA Titratable Acidity

WAC Water Absorption Capacity

WB Wheat Biscuit

wwb Wet weight basis

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List of Appendices

Appendix No. Title Pages

Appendix-I Photo of anchote processing and laboratory equipments used 99

Appendix-II The value of cost indexes (n) for different equipments 101

Appendix-III

Appendix-IV

Factors with separation of materials and labor

Samples of analysis results from Jije Laboglass plc and

EHNRI

102

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Abstract

The effect of boiling, roasting and natural fermentation on anchote flour samples

collected from Nekemte and Dembidollo regions of western Ethiopia were studied for

their effects on proximate composition, antinutritional factors, physicochemical and

functional properties. The moisture content of samples was 6.36% for Nekemte sample

and 6.60% for Dembidollo sample for raw flour samples. Based on dry weight basis, the

ash, fat, protein, crude fibre and total carbohydrate were 3.96, 1.15, 7.28, 3.94, and

77.31%, respectively for the raw sample of Nekmte and 4.67, 0.88, 5.17, 4.73, 77.95% for

the raw sample of Dembidollo. The energy values were 348.71and 340.40Kcal/100g for

Nekemte and Dembidollo samples, respectively. Among antinutritional factors analyzed,

the level of phytate, tannin, oxalate and cyanide, were 20.65, 50.19, 6.56 and

5.32mg/100g in raw Nekemte sample and 33.06, 56.34, 7.32 and 6.06mg/100g in raw

Dembidollo flour samples, respectively. Significant difference (P<0.05) was observed in

level of all the antinutrients of the two samples. A reduction of 29.5, 56.6, 35.8 and

17.50% in the level of phytate, tannin, oxalate and cyanide was achieved by boiling

process, respectively. Fermentation reduced about 54.8, 72.4, 62.6 and 47.7%, in the

level of phytate, tannin oxalate and cyanide in Nekemte sample. Phytate, tannin, oxalate

and cyanide were reduced by 32.8, 52.5, 43.6 and 30.4% by boiling and 65.4, 71.1, 63.5

and 50.3% reduction was achieved by fermentation for Dembidollo sample. Natural

fermentation has resulted in significant reduction in all types of antinutrients. Nekemte

sample is preferred where it contains lowest levels of antinutritional factors compared to

Dembidollo sample. The possibility of using anchote flour for the production of biscuit by

blending with wheat flour was also investigated. Fermented anchote and wheat flour

were blended using 10, 20 and 30% proportion. The proximate composition and mineral

composition of biscuit were evaluated. Sensory qualities of biscuit were evaluated in

terms of color, flavor, crispiness and overall acceptability. The biscuits made from wheat

flour supplemented with 10% fermented anchote flour rated at par to control biscuits

with respect to sensory characteristics without significant difference and also improved

nutritional profile of mineral and crude fiber content significantly.

Key words: Anchote, Fermentation, Boiling, Roasting, Effect of processing, Antinutritional

factors, Physicochemical properties, Functional properties, Composite biscuit

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CHAPTER ONE

INTRODUCTION

1.1 Background

Many of the developing world’s poorest producers and most undernourished households

depend on root and tuber as a contributing, if not principal, source of food and nutrition.

In part, these farm households value root and tuber, because root and tuber produce large

quantities of dietary energy and have stable yields under conditions in which other crops

may fail root and tubers produce remarkable quantities of energy per day, even in

comparison to cereals. Potatoes lead the way in energy production, followed by yam. In

addition, some root and tuber are an important source of vitamins, minerals, and essential

amino acids such as lysine (Scott, et al., 2000). Yared (2007) pointed out that, root and

tuber crops play multi-purpose roles in the global food system as a starch supplier, food

security crop, source of cash income, raw material for feed and processed products, and

as key components in small-scale agro-enterprise development.

Anchote, Coccinia Abyssinica, is an endemic root crop which has been widely grown

throughout the south and southwestern parts of Ethiopia for centuries and belongs the

family Cucurbitaceae family (Abera, 1995).The name ‘anchote’ is derived from

Oromiffa, a native language spoken by the Oromo nationalities in Ethiopia, and refers to

the edible tuber of the cultivated races of Coccinia Abyssinica. It is also known by

different vernacular names at different places and tribe such as ‘ushushe’ in Walaita,

‘shushe’ in Dawero and ‘ajo’ in Kaffa (Amsalu et al., 2008). However, its cultivation as a

root crop is common in Wollega, Iluababor, Jimma, Kaffa, and Sidama (Amare, 1973).

Nutritionally, anchote is a good source of minerals and fiber content. Its protein content is

also by far greater than other root crops, although, root crops are known for their low

protein content. It is rich source of calcium, which is an important constituent of our

bones and teeth. Anchote is also an ample source of potassium and iron. So it can

contribute to the food security in the country (Habtamu, 2011). Anchote root crop not

only have beneficial nutrients, but also contains traces of antinutritional factors, which

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may have adverse effects on health like Phytate, tannin, oxalate and cyanide ( Habtamu,

2011).

Now a day’s industrialization is growing at a much faster rate and among this, food

processing industries cover most of the percentages. Therefore utilization of different raw

materials, which are locally available, at a processing scale is necessary. Among this are

different root crops cover lower parts in the food sector. These root crops include

anchote, potato, carrot, beat root, sweet potato, yam, garlic, and others. The utilization of

the tubers of anchote plant is also categorized under this group. Anchote flour contains

higher amount of minerals and crude fiber than wheat flour (Habtamu Fekadu, 20011).

Biscuit produced from blend of anchote and wheat may have good potential for a number

of reasons. It will increase the consumption of anchote and encourage farmers; the

products will be a more acceptable healthy alternative since it enriches the products by

dietary fiber and minerals. Fibers exhibit beneficial physiological effects to human body,

as they stimulate and accelerate intestinal contraction and transit (Ahmed et al, 2010).

1.2 Statement of the problem

One major limiting factor in the utilization of root crops is the presence of antinutritional

factors, which may have adverse effect on health through inhibition of digestion,

absorption, and growth. Root crops, in common with most plants, contain small amounts

of potential toxins and antinutritional factors (FAO, 1990). Taro contains large amount of

Phytate (855mg/100g) (FAO, 1990). Marfo and Oke (1988) have shown that cassava,

cocoyam and yam contain 624 mg, 855 mg and 637 mg of phytate per 100 g respectively.

Abdulrashid and Agwunobi (2009) reported oxalates, phytates and tannins are the anti-

nutritional factors found in taro The high content of calcium oxalate crystals, about 780

mg per 100 g in some species of cocoyam, Colocasia and Xanthosoma, has been

implicated in the acridity or irritation caused by cocoyam (Oke, 1967). Phytate reduces

protein and mineral bioavailability (Khare, 2000). Tannins reduce protein digestibility

and adversely influencing the bioavailability of non-haem iron leading to poor iron and

calcium absorption (Adeparusi, 2001). Oxalic acid forms water soluble salts with Na+,

K+, and NH4+ ions. It also binds with Ca2+, Fe2+ and Mg2+ rendering these minerals

unavailable to animals (Noonan & Savage, 1999). Understanding the level of

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antinutritional factors in anchote and processing methods that are effective in reducing

these factors may significantly contribute in reducing health risk that are associated with

consumption of anchote.

As described by Elevina E. Perez Sira, (2000), before consideration is given to tubers as

potential sources of flour and starch to produce foods, it is necessary to characterize their

chemical composition, physical, physicochemical and functional properties.

Understanding the physicochemical and functional properties of flours from the raw and

processed anchote may help us in utilization of anchote flour with other flours and the

development of value added products from anchote.

Although the anchote is familiar to the farmers in the region, a full understanding of the

economic, ecological and nutritional advantages is lacking in many parts of the region.

The production of anchote flour is not practiced. Replacement of part of wheat flour with

non-wheat ingredients for the production of cookies and baked products had been

reported by various researchers (Sammy et al., 1970). Nip et al. (1994) have reported that

taro flour can be used to partially replace regular wheat flour for cookie manufacturing.

Anchote is under-utilized endemic crop. The development of value-added products from

anchote flour is unknown, but may have good potential for a number of reasons. It could

increase opportunities to expand the utilization of anchote and could help improve the

economy of various anchote-producing areas. Considering the nutritional status of

anchote that is more than twice of the protein, ash and dietary fiber content of root crops

and containing high amounts of calcium, potassium and iron (Habtamu and Kelbessa,

1997; Habtamu Fekadu, 2011), blending anchote flour in biscuit formulation with wheat

flour could also be very beneficial.

1.3 Objectives

� General objective

The general objective of the research was to study the effects of various methods of

processing on nutritional compositions, anti-nutritional factors, physicochemical and

functional properties of anchote flour and to develop anchote-wheat based biscuit.

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� Specific Objectives

The specific objectives of this research were

1. Analysis of proximate composition, antinutritional factors, physicochemical and

functional properties of raw and processed anchote flour samples

2. Compare the proximate composition, antinutritional factors, physicochemical and

functional properties of anchote flour samples collected from two different

regions of Ethiopia

3. Evaluate the effect of processing methods (boiling, roasting and natural

fermentation) on proximate composition, antinutritional factors, physicochemical

and functional properties

4. Proximate composition analysis and sensory evaluation of anchote-wheat based

biscuit

5. To evaluate techno-economic feasibility of anchote-wheat based biscuit

1.4 Significance of the study

Generally the study will result the following benefits

• Provide information about the effect of processing on physicochemical

composition, functional properties and antinutritional factors of anchote

• They can also provide income opportunities for local communities involved in

agricultural practices of the crops and diversify farmers’ incomes as well

• Blend formulation with other cereals

• Resource utilization maximization

• Value addition

• Add variety to the agro-processing industry

• Researchers, government and other organization may use the outcome of this

research as a reference materials

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CHAPTER TWO

LITERATURE REVIEW

2.1 Origin and Distribution of anchote

Anchote (Coccinia Abyssinica) belongs to the family Cucurbitaceae. Endashaw Bekele

(2007) reported that there are ten species of the genus in the country. Of these, Coccinia

Abyssinica is the only species grown for its edible tuberous roots. It is an annual trailing

herbaceous vine whose young shoots and tuberous roots are processed and used as

vegetables and root crops, respectively (Abera Hora, 1995; Endashaw Bekele, 2007;

Habtamu Fekadu, 2011).

Edwards (1991) indicated that anchote is found in many parts of the country, including

the western, southeastern and northern parts. But, anchote is cultivated as a root crop only

in the west, southwest and southern regions of the country (Amare, 1973). It is also

reported that the crop is grown and much liked in all parts of Wallagga, lllubabor, Jimrna,

Kafa and Sidamo (Amare 1973). Abera Hora (1995) also pointed out the presence of

anchote in the Southern Nations, Nationalities and Peoples’ and Abera, also indicated that

the regions have their own local name for anchote. Zemede Asfaw (1997) also gave a

sign on the presence of Anchote in northern parts of Ethiopia (Gonder, Gojam) and Bale

though he didn’t clarify as to what role anchote has and whether it is cultivated or wild in

those areas. There are also some literatures indicating the presence of anchote relatives,

whose fruits are consumed, in Kenya, e.g. Coccinia grandis and Coccinia triloba

(Maundu, 1999). Generally speaking, many authors agreed that the center of origin and

diversity for anchote seems to be the western and southwestern areas of Ethiopia.

2.2 Ecology and agriculture of anchote

The crop seems to have a wider ecological adaptation as it grows well in ‘Qolla’,

‘Weinadega’ and ‘Dega’ (Amh.), the traditional agro-ecological zones of Ethiopia based

on relative altitudinal ranges; 500-1500 m, 1500-2300 m and 2300-3200 m above sea

level, respectively (Zemede Asfaw, 1997). But, there is almost no research information

on the ecological adaptation of the crop. In the growing regions, very fertile soils in

homestead areas are used for anchote cultivation. The information on other soil types is

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lacking. According to Abera Hora (1995), southwestern parts of Ethiopia with oxisol,

ultisol and vertisol soil types, altitudinal range of 1500-2400 m.a.s.l, receiving an annual

rain fall of about 1500 mm to over 2000 mm might be suitable for anchote. But, on the

contrary, he also found anchote growing in areas outside the indicated ecological limits.

According to Holstein and Norbert (2011), Coccinia species can grow on lateritic soils

(i.e. red tropical soils), and are distributed in semi-arid, wood-lands and forest habitats of

Sub-Saharan Africa.

Tubers vary in shape depending on environmental conditions, but generally spherical or

elongated at maturity. Almost all activities associated to anchote culture are done by

women (Abera Hora, 1995; Endashaw Bekele, 2007). Land preparation, sowing,

weeding, staking, harvesting, processing, storing and marketing are mainly accomplished

by women, and usually, home gardens are used for anchote growing. Pests such as

porcupines, wild pigs, and wart hogs hunt anchote tubers. The vicinity of anchote plots to

home area helps family members and guarding dogs in protection. Parasites of fungal,

bacterial, viral, and/or nematode origin and insect pests may also attack the aerial and/or

underground parts of the plant.

Anchote can be propagated both vegetatively and by seeds. In the vegetative propagation,

high quality tubers that might have been obtained from market or any other source, can

be planted and used as seed sources during the next growing season. Some tubers may

also be left in soil for regrowth as ‘guboo’ (Oro.) for the coming season (Abera Hora,

1995; Habtamu Fufa and Kelbessa Urga, 1997; Endashaw Bekele, 2007). But, the

commonest way of anchote propagation is via seeds. Mature red/yellow fruits are

collected and seeds extracted. The seeds are stored in safe area and used during the

coming season. Sowing is by broadcasting, although sowing in line may increase tuber

quality (Abera Hora, 1995). Staking may be essential to increase fruit number, and

thereby seed production. Fencing may also be important to protect the aerial parts of

anchote from devastation by domestic animals such as sheep, goats, donkeys, and the

like.

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2.3 Importance of anchote

Anchote is endemic root crop of Ethiopia and it is a unique root crop in its uses and the

parts consumed. All the three harvestable parts of anchote (i.e. seeds, shoot tips and

tubers) are marketable even though the root is the most economic concern in most

growing areas of Ethiopia. The consumable parts: root, leaf, and fruit are rich in protein,

calcium, iron, and potassium. Few analyses made on the food content of anchote show

that anchote is best in protein, utilizable carbohydrate, iron and calcium content as

compared to some root crops grown in anchote growing areas and fourth after enset,

sugar beet and potato in energy content, (Table 2.1). The crop has been contributing

much to the diet of the rural societies in its growing areas since its domestication (Amare

Getahun, 1976). As its protein, calcium, iron and carbohydrate contents are better than

other root crops, it could be an excellent source of macro- and micronutrients. But, its

agriculture needs to be modernized and scaled up. As native biological resources are

adapted to local conditions, due attention should be given to such crops (Legesse Negash,

2010). Traditional indigenous crops have the potential to diversify and expand the diet of

the local societies in particular, and the world, in general (Habtamu Fekadu, 2011).

In addition to its nutritional importance, anchote is a cultural and medicinal crop widely

used in growing areas (Amare Getahun, 1976). Anchote is a local dish highly

recommended for individuals suffering from bone fractures and displaced joints. The

belief that anchote has a repairing effect is knowledge gained by the Oromo elders from

years of practical experience. More than its other uses, anchote is getting popular because

of its medicinal value even with the non-Oromos (Abera Hora, 1995). The high medicinal

value of the anchote tuber seems to be because of its high calcium as compared to other

common and widespread root and tuber crops (Abera Hora, 1995). Possibly its calcium

content is important in repairing damaged bones. Juice prepared from roots of anchote

has been used in Ethiopian traditional medicine. Spiced and flavored anchote paste is

recommended for people suffering from bone fracture and displaced joints (Amare

Getahun, 1976; Habtamu Fufa and Kelbesa Urga, 1997; Endashaw Bekele, 2007).

According to Abera (1995), juice of anchote root is used to treat cancer, tuberculosis,

skin eruptions and gonorrhea by traditional medicine practitioners of Ethiopia.

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Anchote has a special place in the traditions and customs of the Oromo people in the

anchote growing areas. According to Abera Hora (1995), the inclusion of anchote in

dishes served at ritual ceremonies is prestigious. Anchote dishes in different forms are

usually served in special occasions such as the ‘masqal’ celebration in September,

weddings, marriage ties (betrothals), circumcision, birth days and thanks giving days at

the start of a New Year, or harvest time. During such occasions and/or at times of

physical injuries, a neighbor that has no anchote for that season may get a present of

anchote tubers from those who have it. This is done to share their happiness and

strengthen social relationships. So, anchote has considerable social importance in the

anchote growing societies.

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Table 2.1 Comparison of the main composition of anchote and some root crops

commonly grown in southern and southwestern parts of Ethiopia (per 100g edible portion

based on wet weight basis)

Source: Agren and Gibson (1968), Bradbury and Holloway (1988) cited in Abera Hora (1995), Teshome

Alemayehu and Muluneh Girma (2005) and Habtamu Fekadu (2011). NF= not found

Factors Anchote

(Coccinia

abyssinica)

Sweet potato

(Ipomoea

batatas)

Potato

(Solanum

tuberosum)

Oromo

potato

(Plectranth

us edulis)

Enset

(Ensete

ventricos

um)

Cassava

(Manihot

esculenta)

Major contents(g)

Moisture 74.93 67.40 74.7 81.2 48.7 62.8

Crude protein 3.25 1.30 1.6 1.5 0.6 0.53

Utilizable

carbohydrate

16.86 28.20 22.6 16 49 31.0

Crude fat 0.19 2.0 0.1 0.2 0.3 0.17

Total ash 2.19 1.10 0.6 1.1 0.9 0.84

Crude fiber 2.58 1.10 0.4 0.7 1.2 1.48

Gross energy

(Kcal)

82.12 136.00 97.0 71 200 NF

Minerals & cyanide(mg)

Ca 119.5 52.00 10.0 29 82 20

Fe 5.49 3.40 6.7 9.3 3.7 0.23

P 34.61 34.0 40 90 36 46

Mg 79.73 NF NF NF NF 30

Zn 2.23 NF NF NF NF NF

Cyanide 12.67 NF NF NF NF NF

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2.4 Traditional processing of anchote

Aerial parts and fibrous roots are removed from the tubers. After thorough washing, they

are boiled in a clay pot called ‘xuwwee’ (Oro.). To achieve rapid cooking, the pot is

covered by leaves of enset, maize, sorghum, or pumpkin. Final sealing may be by a lid or

cow dung. This arrangement minimizes heat loss. The well-boiled tubers are then, cooled,

peeled and processed in different ways. Anchote tubers are, most of the time, consumed

boiled (Abera, 1995).

Habtamu Fekadu (2011) mentioned the consumption of raw anchote, but this is

uncommon. Boiling decreases both nutritional and anti-nutritional (substances that

interfere with food utilization and affect health in animals including humans) contents of

foods by leaching and/or decomposition (FAO, 1990; Makkar, 1993). But, boiling makes

most foods palatable, increases digestibility and bioavailability of some nutrients,

inactivates some anti-nutritionals and enzyme inhibitors, and increases consumer

preferences (FAO, 1990; Habtamu Fekadu, 2011). Except for moisture, crude fiber and

iron, all contents were seen reduced after boiling. But, boiling after peeling caused more

reduction in both nutritional and anti-nutritional contents (Table 2.2). Reduction in the

anti-nutritionals such as phytate, oxalate, tannin and cyanide is desirable. Loss of the

nutritions is disadvantageous. So, boiling before peeling is recommended for anchote as

this minimizes the nutritional losses and unnecessary moisture gain. Dish preference may

also depend on processing. According to Habtamu Fekadu (2011), 66% of anchote

consumers given, at a time, both ‘boiled-after-peeling’ and ‘boiled-before-peeling’

anchote dishes, have preferred dishes from ‘boiled-before-peeling’ anchote tubers.

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Table 2.2 Nutritional and anti-nutritional composition of raw and processed anchote

tubers (based on wet weight basis of the sample)

(Source: Habtamu Fekadu, 2011)

Contents Raw Boiled-after peeling Boiled-before-peeling

Nutrients (g/100g)

Moisture 74.93 81.74 76.73

Crude protein 3.25 2.67 3.14

Total ash 2.19 1.33 1.99

Crude fiber 2.58 3.71 2.77

Crude fat 0.19 0.13 0.14

Utilizable carbohydrate 16.86 10.42 15.23

Gross

energy(Kcal/100g)

82.12 53.48 72.26

Minerals (mg/100g)

Ca 119.50 115.70 118.20

Fe 5.49 7.60 6.60

Mg 79.73 73.50 76.47

Zn 2.23 2.03 2.20

P 34.61 28.12 25.45

Antinutritional factors (mg/100g)

Phytate 389 333 334

Oxalate 8.23 4.23 4.66

Tannin 173.55 102.36 121.21

Cyanide 12.67 8.16 11.14

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2.4.1 Traditional ways of serving anchote

� Boiled anchote tubers served as chips/slices (‘Murmura ancootee’/Oro.)

The tuber is sliced longitudinally into several chips and served with ‘difo dabo’ (Amh.)

and ‘qocqocaa’ (Oro.), a paste of green or red pepper with pungent taste; also known as

‘daaxaa’ in southern Ethiopia. ‘Qocqocaa’ is flavored with a traditionally processed

butter ‘nitir qibe’ (Amh.) and other spices. Such chips are mainly served on special

occasions such as the ‘masqal’(Abera, 1995).

� Boiled anchote tubers as paste (‘Ancootee lanqaxxii’ /Oro.).

The boiled, peeled and washed tubers are chopped into smaller pieces and ground using

‘dhagaa daakuu’ (Oro.)/ ‘yej wofcho’ (Amh.) - Ethiopian traditional mill. The resulting

paste is flavored with processed butter and others, including salt (Abera, 1995). This is

then served with ‘injera’ or bread. This anchote dish is the form being served in small

and large hotels and restaurants in Addis Ababa and anchote growing areas. In Addis

Ababa, it is available in hotels/restaurants owned by businessmen of anchote growing

area origin, e.g. Hawi Hotel around ‘Global’.

� Boiled anchote tubers as stew (‘ittoo’/Oro.; ‘ wat’/Amh.)

Boiled tubers are peeled and chopped into pieces and made into a stew, alone or in

combination with legumes such as haricot beans, peas, or with meat. This is then salted,

flavored and served with ‘injera’ (Abera, 1995).

Figure 2.1. Boiled anchote tubers (after peeling) Source: Habtamu Fekadu (2011)

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� Toasted tubers (‘tibs’/ Amh.)

Slightly boiled/unboiled and peeled tubers are chopped up and toasted using oil and a

limited amount of water. This is then, served with other foods after adding the necessary

ingredients (Abera, 1995). In addition to the above major anchote dishes, Abera Hora

(1995) mentioned the following miscellaneous dishes.

� Miscellaneous anchote dishes

Baked anchote (‘dibaa ancootee’, Oro.) - few tubers are baked by placing them under

glowing fire or hearth. They are peeled, sliced vertically, and served alone or with other

food items.

Anchote soup (‘Mooqa ancootee’, Oro.) - unboiled tubers are peeled, chopped into

pieces, sun dried and ground/pounded. The flour is then, used to make anchote soup.

These last two anchote dishes are not widely known among the anchote growing

societies.

2.5 Antinutritional factors

Antinutritional factors have been defined as substances, which by themselves, or through

their metabolic products arising in living systems, interfere with food utilization and

affect the health and production of animals (Francis et al., 2001). Root crops, in common

with most plants, contain small amounts of potential toxins and antinutritional factors

(FAO, 1990). Phytate, tannin, oxalate and cyanide are common antinutritional factors,

which mostly occur in various root crops.

2.5.1 Antinutritional effects of phytate

Phytate is a salt form of phytic acid. Phytic acid acts as a strong chelator, forming protein

and mineral-phytic acid complexes; the net result being reduced protein and mineral

bioavailability (Khare, 2000). Phytic acid is reported to chelate metal ions such as

calcium, magnesium, zinc, copper, iron and molybdenum to form insoluble complexes

that are not readily absorbed from gastrointestinal tract. Phytic acid also inhibits the

action of gastrointestinal tyrosinase, trypsin, pepsin, lipase and amylase (Khare, 2000).

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The major concern about the presence of phytate in the diet is its negative effect on

mineral uptake. Especially zinc and iron deficiencies were reported as a consequence of

high phytate intake (Greiner et al., 2006). Phytic acid decreases the availability of zinc,

manganese, copper, molybdenum, calcium, magnesium, iron as well as protein (Beleia et

al., 1993). When bound to protein, it induces a decrease of solubility and functionality of

the protein. Phytate lowers the bioavailability of certain minerals through formation of

insoluble complexes at intestinal pH. Adane and Gullelat (2009) and Huang, et al.

(2007) reported phytate concentrations (115.43- 135.28mg/100g) for unprocessed taro

cultivars. For raw and processed cassava, Tilahun and Shimelis (2009) reported phytate

content of 543.97mg/100g to 168.24mg/100g. The phytate content of cassava flour

reported by (Edeogu and Ekuma, 2007), ranges from 253 to 400 mg/100g.

In average, the daily intake of phytate was estimated to be 2000–2600 mg for vegetarian

diets as well as diets of inhabitants of rural areas of developing countries and 150–1400

mg for mixed diets (Reddy NR, 2002). Hurrel, R. F et al. (1992) reported that phytic acid

intake of 4-9mg/100g is said to decrease iron absorption by 4-5 folds in humans.

2.5.2 Antinutritional effects of tannins

Tannins are water soluble phenolic compounds with a molecular weight greater than 500

daltons. They have the ability to precipitate proteins in aqueous solution (Kumar and

Horigome, 1986; D’Mello, 2000). Tannins are secondary compounds of various chemical

structures widely occurring in plant kingdom (Francis et al., 2001). They are defined as

high-molecular-weight polyphenolic compounds that have the ability to bind with protein

and preserve animal hides. Tannins are generally divided into hydrolysable (glucose

polyesters of Gallic or hexahydroxydiphenic acids) and condensed tannins

(proanthocyanidins) (Bender, 2006).

Tannins readily form indigestible complexes with proteins and other macro-molecules

under specific environmental conditions, up on this, they reduce protein digestibility and

adversely influencing the bioavailability of non-haem iron leading to poor iron and

calcium absorption, also carbohydrate is affected leading to reduced energy value of a

diet containing tannins (Adeparusi, 2001).

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Tannins also reduce the absorption of vitamin B12. Contrary to condensed tannins, the

hydrolysable tannins are easily degraded in biological systems, forming smaller

compounds that can enter the blood stream and over a period of time cause toxicity to the

organs (e.g., liver and kidney) (Francis et al., 2001).

Tannins may form a less digestive complex with dietary proteins and may bind and

inhibit the endogenous protein, such as digestive enzymes. Tannin-protein complexes

involve both hydrogen bonding and hydrophobic interactions. The precipitation of the

protein-tannin complex depends upon pH, ionic strength and molecular size of tannins.

Both the protein precipitation and incorporation of tannin phenolics into the precipitate

increase with increase in molecular size of tannins (Kumar and Horigome, 1986).

However, when the molecular weight exceeds 5,000 daltons, the tannins become

insoluble and lose their protein precipitating capacity and degree of polymerization

becomes imperative to assess the role of tannins in ruminant. Tannins have been found to

interfere with digestion by displaying anti-trypsin and anti-amylase activity. Helsper et

al. (1993) reported that condensed tannins were responsible for the testabloat trypsin

inhibitor activity of faba beans. Tannins also have the ability to complex with vitamin B.

Other adverse nutritional effects of tannins have been reported to include intestinal

damage, interference with iron absorption and the possibility of tannins producing a

carcinogenic effect (Butler, 1989). The total acceptable tannin daily intake for man is

560mg (Anonymous, 1973). Adane and Gulelat (2009) reported a tannin concentration in

a range of 47.69 - 59.92mg/100g and Akpan and Umoh (2004) obtained a tannin

concentration of 640mg/100g for raw samples of taro. Cassava also found to contain a

small amount of tannin vary from 3.6 to 6.9mg/100g (Oboh and Akindahunsi, 2003;

Oboh et al., 2002, Fasuyi, 2005).

2.5.3 Antinutritional effects of oxalate

Oxalic acid (or its salts) is widely distributed in the plant kingdom although its nutritional

significance is limited to relatively few plants and forages (Noonan and Savage, 1999).

Ingestion of foods containing oxalates has been reported to cause caustic effects,

irritation to the intestinal tract and absorptive poisoning. Oxalic acid forms water soluble

salts with Na+, K+ and NH4+ ions it also binds with Ca2+, Fe2+ and Mg2+ rendering these

Page 16

minerals unavailable to animals. However Zn2+ appears to be relatively unaffected. In

plants with a cell sap of approximately pH 2, such as some species of Oxalis and Rumex

oxalate exists as the acid oxalate (HC2O4), primarily as acid potassium oxalate. In plants

with a cell sap of approximately pH 6, such as some plants of goosefoot family it exists

as oxalate (C2O4)2- ion usually as soluble sodium oxalate and insoluble calcium and

magnesium oxalates. Calcium oxalate is insoluble at a neutral or alkaline pH, but freely

dissolves in acid (Noonan and Savage, 1999). The high content of calcium oxalate

crystals, about 780 mg per 100 g in some species of cocoyam, Colocasia and

Xanthosoma, has been implicated in the acridity or irritation caused by cocoyam (Oke,

1967). The acridity of high oxalate cultivars of cocoyam can be reduced by peeling,

grating, soaking and fermenting during processing (Oke, 1967). Cooking can affect the

soluble oxalate but not the insoluble oxalate content of the food. Boiling can reduce the

soluble oxalate content of a food if the cooking water is discarded, while soaking,

germination and fermentation will also reduce the content of soluble oxalates (Noonan &

Savage, 1999). The lethal level of oxalate in man is 3-5g as reported by Balogoplan C., et

al. (1998). Relatively high of oxalate content was reported by Adane and Shimelis (2009)

265.88mg/100g and 243.06mg/100g for raw taro samples of two different varieties.

2.5.4 Antinutritional effects of cyanide

Cyanides are organic or inorganic compounds which contains the C=N group (Health

Canada, 1991). Cyanide is toxic to a wide spectrum of organisms as a consequence of its

ability to form complex with metals (Fe2+, Mn2+ and Cu2+) that are functional groups of

many enzymes, inhibiting processes like the reduction of oxygen in the cytochrome

respiratory chain, electron transport in the photosynthesis and the activity of enzymes like

catalase, oxidase (McMahon et al., 1995). Hydrocyanic acid or HCN is a volatile

compound. It evaporates rapidly in water in the air at temperature over 280c and dissolves

readily in water. It may easily be lost during transport, storage and analysis of specimens

(FAO, 1990). The consumption of cyanide even at low levels over a long period can

induce iodine deficiency, leading to goiter (Sahore, et al., 2006). Hydrogen cyanide

inactivates the enzyme cytochrome oxidase in the mitochondria of cells by binding to the

Fe3+/Fe2+ contained in the enzyme. This causes a decrease in the utilization of oxygen in

the tissues. Cyanide causes an increase in blood glucose and lactic acid levels and a

Page 17

decrease in the ATP/ADP ratio indicating a shift from aerobic to anaerobic metabolism.

Cyanide activates glycogenolysis and shunts glucose to the pentose phosphate pathway

decreasing the rate of glycolysis and inhibiting the tricarboxylic acid cycle.

The main toxic principle which occurs in varying amounts in all parts of the cassava plant

is a chemical compound called linamarin (Nartey, 1981). It often coexists with its methyl

homologue called methyl-linamarin or lotaustralin. Linamarin is a cyanogenic glycoside

which is converted to toxic hydrocyanic acid or prussic acid when it comes into contact

with linamarase, an enzyme that is released when the cells of cassava roots are ruptured

(Nartey, 1981). Otherwise linamarin is a rather stable compound which is not changed by

boiling the cassava (Nartey, 1981). Some cultivars of taro also contain small quantity of

cyanide. It contains about 1-5% of cyanide content of cassava (Bradbury and Sylvia,

1995). Hydrogen cyanide will reduce the energy availability in all cells, but its effect will

be most immediate on the respiratory system and heart (Nartey, 1981). In 1991 FAO/

WHO recommended that HCN levels in mammals is 10mg/kg dry weight (10ppm.)

Lethal level of hydrogen cyanide is 36 mg/100 g (Oke, 1969).

2.6 Physicochemical and functional properties

2.6.1 Physicochemical properties

� pH of the flour

The acidity or alkalinity of a food is usually expressed as pH. It gives us information on;

to what extent a certain food sample is acidified. The pH of a food can dramatically alter

the growth of microbes in food and is a major determinant of the type of food

preservation process used for that food. Yeasts and molds usually grow best between pH

4 and 6 and bacteria usually grow best at pH near 7. In selecting a food preservation

process that makes a food shelf stable, the initial pH of that food must be considered to

minimize the likelihood of bacterial growth in that food (Mbofung, 2006).

� Titratable acidity

Titratible acidity measures the total amount of hydrogen ions available in the food and

expressed as mg lactic acid eq/g of the food sample. Titratible acidity is different than

total acidity, although at times both terms are used to mean the same thing. Total acidity

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is the total amount of organic acids in the food sample. The titratible acidity of any food

sample in the form of solution is an approximation of the solutions total acidity usually

measured by reacting the acids present in the food sample with a base such as sodium

hydroxide to the chosen end point close to neutrality, as indicated by an acid sensitive

colour indicator (John, 2007).

2.6.2 Functional properties

Functional properties are very important in determining the level of utilization in

ingredient formulation and new food product development (Fasasi, 2007). As described

by Elevina E. Perez Sira, (2000), before consideration is given to tubers as potential

sources of flour and starch to produce foods, it is necessary to characterize their chemical

composition, physical, physicochemical, and functional properties. The chemical

composition of flours and starches exhibits differences especially in amylose and

phosphorous content, as a function of the botanical origin. It is significant because of the

influence of amylose and phosphorous content in the functional properties of flours and

starches. It is a general consensus that the influence of both amylose and phosphorous

content affects the gelatinization and pasting behavior of starches and flours. These two

parameters determine the functional properties of flours and starches such as: texture,

consistency, binding, coating, adhesiveness, cohesiveness, thickening, viscosity, and

palatability (Sira, 2000).

� Water and oil absorption

The ability to absorb water is a very important property of flours used in food

preparation. The ability of food materials to absorb water is sometimes attributed to the

protein content (Mbfung, 2006). WAC is an important functional property required in

food formulations especially those involving dough handling (Udensi1, et al., 2008).

WAC plays a major role in the functionality of dough. In particular, WAC has been

shown to be related to dough consistency (Njintang, et al., 2008).

It is known that water binding by starches and flours is a function of several parameters

including size, shape, conformational characteristics, steric factors, hydrophilic-

hydrophobic balance in the starch molecule, lipids and carbohydrates associated with the

proteins, thermodynamic properties of the system (energy of bonding, interfacial tension,

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etc.), physicochemical environment (pH, ionic strength, vapor pressure, temperature,

presence/absence of surfactant etc.), solubility of starch molecules and others (Shimelis,

et al., 2006).

� Bulk density

Bulk density gives an indication of the relative volume of packaging material required.

Generally, higher bulk density is desirable for the greater ease of dispersibility and

reduction of paste thickness which is an important factor in convalescent child feeding

(Udensi, and Okoronkwo, 2006)

� Foam Capacity and Stability

Foaming property is very important to improve texture, consistency, and appearance of

food; such as baked and confectionary goods. Foam ability or foaming power (capacity)

corresponds to the ratio of gas volume to liquid volume in foams (Soetrisno, 2007).

Foaming, the capacity of proteins to build stable foams with gas by forming impervious

protein films, is an important property in some food applications, including beverages, as

well as angel and sponge cakes.Stable foams are known to occur when low surface

tension and high viscosity occur at the interface, forming a continuous cohesive film

around the air vacuoles in the foam. Soluble proteins in general play an important role in

the formation of foam and this probably justify why legumes exhibit higher foaming

capacity (Mbofung et al., 2006).

� Swelling Power and Solubility

Swelling power provides evidence of non-covalent bonding between starch molecules.

Factors like amylose-amylopectin ratio, chain length and molecular weight distribution,

degree/length of branching and confirmation determine the degree of swelling and

solubility. Solubility of flours depends on a number of factors such as sucrose, inter-

associative forces, swelling power, presence of other factors, etc (Subramony, 2002).

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2.7 Processing methods as a means of reducing antinutritional factors

Processing methods are critical when utilization of nutrients contained in anchote is

maximized and toxicity due to antinutritional is minimized. Different processing

technology or treatment conditions are reported to eliminate or minimize antinutrients in

root crops. However, more research is needed to evaluate the potential nutritional

advantages of the new crops on the basis of agronomic and morphological characteristics

as well as to determine acceptable threshold levels of each of antinutrients and to make

best use of their nutritional values. Reduction or inactivation of antinutritional factors

through process technology requires knowledge of the type, distribution, chemical

reactivity and thermal sensitivity of these factors within the seed matrix and complete

knowledge of process technologies.

2.7.1 Boiling and roasting

Boiling/cooking and roasting are important food processing methods. As a thermal

process, boiling/cooking could enhance the palatability and nutritional value by

inactivating endogenous toxic factors (Thomas, 1988). Roasting is similar to

cooking/boiling but involves higher temperature and reduced time. Boiling is effective

method in reducing water soluble antinutrients. For example boiling of root crops such as

taro and cassava will lead to significant reduction of oxalates and cyanide respectively

(Albihn and Savage, 2001). Boiling also found to decrease some amount of soluble

Phytate (Kawabata, 2006). Cooking methods for cassava can, if efficiently carried out,

reduce the cyanide content to non-toxic levels. Since boiling needs energy it is not

economical method as other processing methods such as natural fermentation for poor

rural community.

2.7.2 Fermentation

Fermentation also is a very interesting process used in plant foods to increase the

nutritional quality and remove undesirable compounds. Fermentation enhances the

nutrient content of foods through the biosynthesis of vitamins, essential amino acids and

proteins, by improving protein quality and fibre digestibility. It also enhances

Page 21

micronutrient bioavailability and aids in degrading antinutritional factors (Oboh, and

Elusiyan, 2007).

Over the centuries, fermentation has evolved and been refined and diversified. Today, a

variety of food products are derived from this technology in households, small-scale food

industries as well as in large enterprises. Furthermore, fermentation is an affordable food

preservation technology and of economic importance to developing countries. It enhances

the nutritional quality of foods and contributes to food safety particularly under

conditions where refrigeration or other foods processing facilities are not available

(Motarjemi, 2002).

Organic acids produced, such as acetic, lactic, citric, formic and butyric acids, during

fermentation potentiate zinc absorption by forming ligands with zinc. Microbial

fermentation enhances zinc bioavailability through hydrolysis induced by microbial

phytase enzymes Reduction of phytates in the diet could also favor enhanced absorption

of other minerals like calcium and iron (Sandberg and Andlid, 2002).

Fermentation reduces phytate content via the action of phytases that catalyze conversion

of phytate to inorganic orthophosphate and a series of myoinositols, lower phosphoric

esters of phytate (Sandberg and Andlid, 2002).

There are differences in optimal conditions for phytate degradation between plant

species. Most cereal phytases have pH optima between 4·5 and 5·6, but pH optima of

some legumes are neutral or alkaline. To optimize the food process for increased mineral

bioavailability by phytate degradation, it is essential to know optimal conditions for the

phytases, responsible for phytate degradation in the process (Sandberg and Andlid, 2002).

Hydrolysis of phytate during biological food processes and preparation such as

fermentation is a result of activity of phytase enzymes, naturally synthesized by plants

and many microorganisms. Phytases (InsP6-phosphohydrolases) are by definition

enzymes able to hydrolyse InsP6 to InsP5 and inorganic phosphate (Pi). Typically,

phytases are not specific for InsP6; leading to further hydrolysis to myo-inositol via

intermediate myo-inositol phosphates (penta- to monophosphates). Phytases constitute a

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subgroup of the family of acid phosphatases. Those that exhibit the ability to hydrolyse

InsP6 can be considered to be phytase (Sandberg and Andlid, 2002).

It is also reported that fermentation can reduce tannin content of foods. Reduction in

tannin due to processing might have been caused by the activity of polyphenol oxidase or

fermented microflora on tannins (Fagbemi et al., 2005).

All over the world, fermented foods provide an important part of human diet. Fermented

foods and beverages provide about 20-40% of human food supply. Traditional food

fermentation is capable of improving nutrients of the food, preserve it by generating

acidic condition, detoxify and reduce cooking time of the food (Fagbemi et al., 2005).

Fermentation are found to be useful in flavouring foods, in inhibiting spoilage bacteria

and pathogens, in intestinal health and other health benefits related to blood cholesterol

levels, immune competence and antibiotics production (Sobowale, 2007). Lactic acid

fermentation is inexpensive and often little or no heat is required during the process thus

making it fuel efficient (Shimelis and Rakshit, 2008).

Fermentation generally improves extractability of minerals, probably because of the

decreased content of phytic acid in the fermented product (Eltayeb et al., 2007).

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CHAPTER THREE

MATERIALS AND METHODS

3.1 Materials

Tubers of anchote were obtained from local markets of Nekemte and Dembidollo regions

(western Ethiopia). Soft wheat flour, shortening, sugar, skimmed milk powder,

ammonium bicarbonate sodium bicarbonate, sugar syrup, water, flavor and color were

obtained from Kaliti Food Share Company. Polyethylene bags, cooking utensil,

aluminum foil, ice box, stainless steel knives, tray from local markets and different

laboratory equipments were purchased and used in this study. Sample preparation was

done at Addis Ababa Institute of Technology Chemical Engineering Department

laboratories and Kality Food Share Company. The proximate, mineral and antinutritional

analysis was carried out at Ethiopian Health and Nutrition Research Institute and Jije

Laboglass p.l.c.. Physicochemical and functional properties were determined at Chemical

Engineering laboratories.

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3.2 Framework of the experiment

Proximate analysis

Fermented anchote flour

Roasted anchote flour

Samples of tubers of anchote

Proximate analysis

Sensory analysis

Crude Protein

Crude Fat Crude Fiber Moisture Total ash Minerals

Antinutritional factors (ANF)

analysis

Raw anchote flour

Crude Protein

Crude Fat Crude Fiber Moisture Total ash Minerals

Biscuit

Physicochemical and functional properties Analysis

Phytate, Tannins Oxalate, Cyanide

Boiled anchote flour

Wheat flour

Proximate analysis

Crude Protein

Crude Fat Crude Fiber Moisture Total ash

Page 25

3.3 Processing methods

3.3.1 Flour preparation from raw, boiled, roasted and fermented anchote tubers

� Flour preparation from raw anchote tubers

The raw anchote flour was prepared by the method described by Njintang et al. (2006) for

taro flour preparation with some modifications. All the samples were cleaned manually to

remove foreign matters adhering to it and hand peeled carefully using stainless steel knives

and the peeled anchote were washed and sliced to 0.5cm thick slices. The slices were dried

overnight in a hot air oven at 500c. The dried anchote chips were milled using an electric

miler (model: A11B, Germany) and sieved to pass through 100 mesh sieve, packed, stored

until analysis.

Figure 3.1 Anchote flour from raw anchote tuber

� Flour preparation from boiled anchote tuber

Boiled anchote flour was prepared based on the method described by Babajide et al. (2006) for

yam flour preparation with some modifications. Samples were carefully selected and cleaned to

remove adhering materials and soils. Then they were thoroughly washed using a running tap

water. About 500g medium size samples of cleaned and washed anchote were placed in

cooking utensil and 1500ml of water were added to it and the cooking utensil were placed

Drying in oven (500c)

Selecting fresh anchote

Washing of anchote

Peeling and slicing (0.5cm)

Grinding and sieving (0.1mm)

Packaging and storing

Page 26

over a hot plate to boil. The time of boiling were recorded after the water start to boil and

allowed to boil for 2hrs until they become soften. After boiling the water were discarded and

the boiled tubers were allowed to drip dry. Then the tubers were hand peeled and sliced in to

approximately 0.5mm thick and placed on a stainless steel tray and allowed to dry in oven at

500c over night to a constant weight. The dried anchote chips were converted to flour using

electric miller (model: A11B, Germany) and sieved to pass through 100 mesh sieves and

packed in polyethylene bags and stored in desiccators until analysis.

Figure 3.2 Anchote flour from boiled anchote tuber

� Flour preparation from roasted anchote tuber

Roasted anchote flour was prepared based on the method described for yam flour preparation by

Babajide et al. (2006) with some modifications. Fresh, equal and medium sized anchote

samples were selected and washed thoroughly. The cleaned anchote samples were pierced

with fork and baked in oven preheated to 4000F to approximately 1hr until its body and

texture becomes soft. Then the tubers were hand peeled and sliced in to approximately

Selecting fresh anchote

Washing of anchote

Boiling with the skin

Peeling the boiled Anchote

Slicing to pieces

Drying in oven (50oc)

Grinding and sieving (0.1mm)

Packaging and storing

Page 27

0.5mm thick and placed on a stainless steel tray and allowed to dry in oven at 500c over night

to a constant weight. The dried anchote chips were converted to flour using electric miller

(model: A11B, Germany) and sieved to pass through 100 mesh sieves and packed in

polyethylene bags and stored in desiccators until analysis.

Figure 3.3 Anchote flour from roasted anchote tuber

� Flour preparation from fermented anchote tuber

Fermented anchote flour was prepared based on the method described for yam flour preparation

by Babajide et al. (2006) with some modifications. For fermentation, about 100g of raw

anchote flour were mixed with 300ml of distilled water in 1000ml conical flask and the flask

mouth was covered with aluminium foil and allowed to ferment naturally (spontaneously) at

room temperature (250c) for 72 hours. After 72 hours of fermentation the slurry were

transferred to glass bowls and placed in oven to dry over night at 500cto a constant weigh.

Peeling the Roasted anchote

Selecting fresh anchote

Slicing to pieces

Drying in oven (50oc)

Washing of anchote

Roasting with the skin (4000F, 1hr)

Grinding and sieving (0.1mm)

Packaging and storing

Page 28

Then the dried slurry were milled to flour using electric miller (model: A11B, Germany),

sieved, packed and stored in a desiccators.

Figure 3.4 Anchote flour from fermented anchote tuber

3.3.2 Blend formulation

Three different blend proportions were prepared; the blend proportions were based on the

blend proportions designed by Nip, et al. (1994) for taro-wheat flour sugar snap cookies.

1. 10% fermented anchote flour + 90% wheat flour (AWF1)

2. 20% fermented anchote flour + 80% wheat flour (AWF2)

3. 30% fermented anchote flour + 70% wheat flour (AWF3)

4. 100% wheat flour (control) (WF)

Drying in oven

Selecting fresh anchote

Grinding (0.1mm)

Fermenting

Washing of anchote

Peeling and slicing

Drying in oven

Grinding and sieving (0.1mm)

Packaging and storing

Page 29

3.3.3 Processing method of biscuit made from anchote-wheat composite flour

The three blend formulations and the control flour were baked. The baking formula was

wheat flour or anchote-wheat flour blends 60.7%, Sugar 13.35%, Salt 0.41%, Shortening

5.25%, Skimmed milk powder 0.3%, Ammonium bicarbonate 0.79%, Sodium bicarbonate

0.15%, Sugar syrup 4.25%, Flavor 0.06%, Color 0.03% and water 14.71%. The baking

formula was adopted from Kality Food Share Company with some modifications (Pedersen,

2004).

Biscuits were produced according to a commercial formulation and baking practice of Kality

Food Share Company (Pedersen, 2004). The prepared fermented anchote flour was blended

with wheat flour as given below along with other ingredients. Then the dough was kept at a

normal room temperature for about 5 minutes to allow proper fermentation. Then fermented

dough was placed in biscuit molding rollers so that it attains the proper thickness (1.5mm).

Then this thin dough was shaped using a cylinder of model G.P.A. Orlandi SPA Verona,

Italia. Samples were baked in an Electric Convection Oven (model: G.P.A. Orlandi oven,

Italy, 1993) at 1700C for 5 min, and were allowed to cool for about 15 min on a rack. Then

the biscuits are ready for packaging and distribution. The preparation and processing flow

diagram is shown in Figure-3.6.

Page 30

3.4 Analysis methods

3.4.1 Proximate and mineral analysis

� Determination of crude protein

Protein content was determined according to AOAC (2000) using the official method 979.09.

A digestion flask containing about 1 g of sample, to which 6 ml of acid mixture (conc.

sulphuric acid and conc. orthophosphuric acid) and about 3g of catalyst mixture (K2SO4 and

Selenium) were added and exposed to about 3700c in order to allow digestion. Then,

distillation took place in Kjeltec 2300 Analyzer unit (FOSS, Sweden) by adding 25 ml of

40% NaOH and using 25 ml of boric acid with 10 drops of indicator solution. Finally, the

distillate was titrated with standardized 0.1N sulphuric acid to a reddish color. The crude

protein content was estimated using the formula:-

Other ingredients

1. Sugar 2. Salt 3. Shortening 4.Skimmed milk powder 5. Ammonium bi carbonate 6.Sodium bi carbonate 7. Sugar syrup 8. Flavor 9. Color

Flour Other ingredients Water

Mixing

Shaping and cutting

Kneading

Laminating

Baking Packaging and

storing

Creaming

Fig 3.5 flow diagram for biscuit production

Page 31

Total nitrogen percentage = ……………………… (3.1)

Where, V2 = volume in ml of the standard sulphuric acid solution used in the titration of the

test material

V1 = volume in ml of the standard sulfuric acid used in the titration for the blank

determination

N = normality of the standard sulphuric acid

W = weight in grams of test material

The conversion factor is 6.27 for anchote, which is obtained from food composition table of

EHNRI.

Crude protein content (%) = total nitrogen (%) × 6.27 ………………………. (3.2)

� Determination of crude fat

A clean and dried thimble containing about 5 g of dried sample and covered with fat free

cotton at the bottom and top was placed in the extraction chamber. Then, extraction took

place using 2055 Soxtec extraction unit (FOSS extractor, Sweden) for at least 4 hrs according

to AOAC (2000) official method 4.5.01. The crude fat content was determined by the

formula:-

Crude fat (%) = …………………………………………………….. (3.3)

Where, M2 = mass of flask and lipid extracted, M1 = mass of dried flask

M = weight of sample on dry basis

� Determination of crude fiber

Crude fiber analysis was conducted using the method of AOAC (2000) official method

962.09. About 1.6g weighed sample was transferred into a 600 ml beaker and about 200 ml

1.25% sulfuric acid was added and boiled for 30 minutes. Recording took place by placing a

watch glass over the mouth of the beaker. After 30 minutes heating by gently keeping the

level constant with distilled water, 20 ml 28% KOH was added and boiled gently again for

another 30 minutes. Subsequently, washing was conducted with 1% sulfuric acid and NaOH

Page 32

solution. After, filtering it was then dried in an electric oven (Memmert 854 Schwabach,

West Germany) at 1300C for 2hrs. Furthermore, it was cooled at room temperature for 30

minutes in a desiccators and weighed, then transferred the crucibles to muffle furnace

(Carbolite Aston Lane, Hope,S20 England.) for 30 minute ashing at 5500C. Finally, it was

cooled again in desiccators and reweighed. The crude fiber content was determined by using

the formula:-

Crude fiber content = ……………………………… (3.4)

Where, W1= crucible weight after drying, W2 = crucible weight after ashing, W3 = dry weight

M = % moisture of the sample

� Determination of moisture content

Moisture was determined according to AOAC (2000) using the official method 925.09. A

clean dried and covered flat aluminum dishes were weighed and about 5gm of the sample

were transferred to the dish. The dish then placed in the oven (Memmert 854 Schwabach,

West Germany) at 1020C for overnight and cooled in desiccators and re-weighed. Then, the

moisture content was estimated by the formula:-

MC (%) = ( ) × 100 ……….. (3.5)

� Determination of total ash The porcelain dish used for the analysis was washed by dilute hydrochloric acid on boiling.

And it was washed with distilled and de-mineralized water respectively. Then dried at 1200C

in an oven and ignited at 5500C in (Carbolite, Aston Lane, Hope, Sheffield s30 2RR,

England) furnace for 3 hour. The dish was then removed from furnace and cooled in

desiccators. The mass of the dish was measured using (ARZ140, N315, SNR=1203290469,

USA) analytical balance (M1). About 2.5 gm of sample powder was weighed in to the

porcelain dish (M2).The sample was charred at 1200C on hot plate (Wagtech, UK, hot plate

SH3), until the whole content becomes carbonized. Then the sample was placed in a

(Carbolite, Aston Lane, Hope, Sheffield s30 2RR, England) furnace at 5500C until whitish

Page 33

color appears. The sample was removed from the furnace and placed in desiccators. Finally

the mass was weighed as (M3).

Ash (%) = × 100 ………………………………………………………….... (3.6)

M1 = mass of the dried dish

M2 = mass of the dish and the sample (on DB)

M3 = mass of the dish and the ash

� Utilizable carbohydrate determination

The total utilizable carbohydrate was calculated by difference with the exclusion of crude

fiber.

Total carbohydrate (%) = 100 - (crude fat + crude fiber + crude protein + ash) ……... (3.7)

� Total energy in kilo calories

The gross energy (GE) content in each sample was determined mathematically using the

following formulae:

Total energy (Kcal) = (9 × CF + 4 × CP + 4 × CHO) ……………………………….. (3.8)

Where, CF- crude fat content, CP-crude protein content, CHO-carbohydrate content

� Calcium

The calcium content was determined according to the method of Association of Official

Analytical Chemists’ (AOAC, 2000) using the official method Flame Atomic absorption

Spectrophotometery, 923.03. About 1.0g sample was treated with 10ml of concentrated

HNO3 and 4 ml of 70% HClO4. The resulting solution was evaporated to a smaller volume

(7ml) by careful heating and transferred to 50ml volumetric flask. About 1ml of SrCl2.6H2O

was added and made up to volume with distilled water. The solution was sprayed into atomic

absorption spectrophotometer (Perkin Elmer, model 5100 PCAAS, USA) at 422.7nm to

determine the concentration of calcium. The calcium standards used were 0ppm, 5ppm,

10ppm, 20ppm and 30ppm.

Page 34

� Potassium

Potassium was determined according to the method of Association of Official Analytical

Chemists’ (AOAC, 2000) by using the official method Flame Atomic absorption

Spectrophotometery, 923.03. About g of the samples was dry ashed in a muffle furnace

(Muffle furnace size 2, England) at 550˚C for 5 hours until a white residue of constant weight

was obtained. The mineral was extracted from the ash by dissolving the ash in 10 ml HCl

solution (1:1, HCl: H2O). Ashed sample diluted to 25 ml, then 0.2 ml diluted to 100 ml and

stored in clean polyethylene bottles and potassium content was determined using atomic

absorption spectrophotometer (Perkin Elmer model 5100 PCAAS, USA) at 285.2nm.

� Iron

The iron content was determined based on the method described by the method of

Association of Official Analytical Chemists’ (AOAC, 2000) using the official method Flame

Atomic absorption Spectrophotometery, 923.03. 10ml of concentrated HNO3 was added to

about1g of the sample and left overnight. The sample was carefully heated until the

production of red nitrogen dioxide fumes ceased. The sample was cooled and 4ml of 70%

HClO4 was added and evaporated to a smaller volume (7ml) by careful heating. The resulting

solution was quantitatively transferred into 50ml volumetric flask and diluted to the mark

with distilled water. The solution was sprayed into an atomic absorption spectrophotometer

(Perkin Elmer, model 5100 PCAAS, USA) at 248.3nm to determine the concentration of

iron. The iron standards used were 0ppm, 1ppm, 2ppm, 3ppm and 4ppm.

� Zinc

Zinc determination was done based on the method determined according to Association of

Official Analytical Chemists’ (AOAC, 2000) using the official method Atomic Absorption

Spectrophotometery, 923.03. The ash obtained after dry ashing at 525oC was treated with

7ml of 6N HCl to wet it completely and 15ml of 3N HCl was added and the dish was heated

on the hot plate until the solution just boils. Then, it has been cooled and filtered. 10ml of 3N

HCl was added to the dish and heated until the solution just boils. Finally, cooled and filtered

into the graduated flask.

Page 35

Using atomic absorption spectrophotometer (Varian, spectra-10/20, Australia) a calibration

curve was prepared by plotting the absorption or emission values against the metal

concentration in mg/100g for all of the above minerals. Thus reading was taken from the

graph which depicted the metal concentrations that correspond to the absorption or emission

values of the samples and the blank. The metal contents were calculated by using the

formula:-

Metal content (mg/100g) =

−W

xVBA

10

)(……………………………………….. (3.9)

Where, W = Weight of sample in (g)

V = Volume of extract (ml)

A = Concentration of sample solution (µg/ml)

B = Concentration of blank solution (µg/ml)

3.4.2 Physicochemical properties analysis

� Tuber size determination

The sizes of the tubers were measured using a calibrated balance by directly placing the

tubers on the analytical balance after adjusting the balance to zero with in a 72 hours of

harvesting.

� Determination of pH value

The pH of the raw and processed samples was determined according to the method of AOAC

(1984). About 10 g of the samples were weighed in triplicates in 250ml beaker and mixed

with 50 ml of distilled water and stirred for 10 min. The pH of the sample was determined by

dipping the electrode of the Jenway pH meter (Jenway 3510 pH meter) in the mixture. The

pH meter were calibrated using pH 4.0 and 7.0 buffers prior to determination of the pH of the

samples.

� Titratable acidity analysis

The total titratible acidity of anchote flour samples was determined by Pearson’s (1973),

method. About 5 g of the flour sample was macerated for 30 minutes in a beaker with 15 ml

Page 36

of distilled water as 1 part of the flour to three parts of the water (w/v) ratio. A known

volume of water is used for further dilution in order to hydrolyze all the acids in the sample.

Before titration of the sample, the water that is used for dilution purpose will be titrated to be

used as a blank. Three drops of 1% alcoholic phenolphthalein indicator was added to water

extract of the sample (dispersion). The dispersion was then titrated with standard base (0.1N

NaOH) to phenolphthalein end point. The result of determination will be reported as

percentage lactic acid consuming definite volume of 0.1 N NaOH. The end point of the

titration was reached when the white dispersion changed from a clear white solution to a faint

violet colored turbid solution. Triplicate determinations were made in all cases. Finally it is

given that the amount of lactic acid in the sample was determined from the relation (1ml 0.1

N NaOH = 0.009008mg C3H

6O

3).

� Water activity analysis

The water activity of the raw and processed flour was determined using Aqua Lab Lite water

activity measuring unit manufactured by Decagon. Each sample were half filled in a small

plastic cup supplied with the instrument and inserted in to the instrument then the water

activity of each sample were displayed automatically.

3.4.3 Functional properties analysis

� Bulk density

Using the procedure of Okaka and Potter (1979), 50g of Anchote flour were put into a 100 ml

measuring cylinder and tapped to a constant volume and the bulk density (gcm-3) were

calculated using the formula:

Bulk density = ……………………………………. (3.10)

� Water and oil absorption capacities

About one gram of Anchote flour was mixed with 10 ml distilled water or refined palm oil

(frytol) in a pre-weighed 20 ml centrifuge tube. The slurry were agitated for 2 min, allowed to

stand at 280C for 30 min and then centrifuged at 2000 rpm for 20 min. The clear supernatant

were decanted and discarded. The adhering drops of water or oil in the centrifuge tube will be

Page 37

removed with cotton wool and the tube will be weighed, the weight of water or oil absorbed by

about 1 g of flour were calculated and expressed as water or fat absorption capacity (Buchat,

1977).

� Foam capacity and stability

The foam capacity was determined using the method of Coffman and Garcia, (1977) the flour

(2g) was suspended in distilled water (100 ml) and stirred at room temperature for 5 min

using a magnetic stirrer at 10 Ruhrer speed. The contents along with the foam were

immediately poured into a 250 ml measuring cylinder. Volume of foam (ml) after mixing

was expressed as the foam capacity and then volume after 60 min as foam stability.

� Swelling power and solubility

Swelling power and solubility determinations were carried out in the temperature range of

60-90°C (using the method of Leach et al., 1959). About one gram of anchote flour sample

was accurately weighed and quantitatively transferred in to a clear dried test tube and

weighed (W1). About 15 ml of distilled water were added and mixed gently at low speed for

5 min. The slurry was heated in a thermo stated water bath, at 80°C for 30 min with mixing

the suspension intermittently. The test tube was cooled with its content rapidly to 200C.

During heating, the slurry was stirred gently to prevent lumps forming in the flour. Then the

cool paste was centrifuge at 2200rpm for 15 min. The supernatant was decanted immediately

after centrifuging into a pre-weighed evaporating can and dried at 100°C to constant weight

approximately for 4 hours. The weight of the sediment was taken and recorded as (W2) or

swollen mass.

Swelling power = ………………….…………………… (3.11)

Solubility index (%) = × 100 ………..…………………………....... (3.12)

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3.4.4 Antinutritional factor analysis

� Phytate analysis

The phytate content in the sample was determined according to the method described by

Latta and Eskin (1980), and later modified by Vaintraub and Lapteva (1988).About 0.05gm

of dried sample was extracted with 10ml 2.4% HCl in methanol for 1 hr at ambient

temperature and centrifuged (3000 rpm) for 30 minutes. The clear supernatant was used for

the phytate estimation. About 1ml of wade reagent (0.03% solution of FeC13 water) was

added to 3ml of the sample solution and the mixture was centrifuged. The absorbance at

500ηm was measured using spectrophotometer calculated from the difference between the

absorbance of the control (3reagent) and that of the assayed sample. The concentration of

phytate was calculated using acid standard curve and the weight.

To prepare the phytic acid standard curve, a series of standard solution was prepared

containing 5–40 mg/ml phytic acid in water. About 3ml of the standards was pipetted into

15ml centrifuge tubes with 3ml of water used as a zero level. To each tube was added about

1ml of the wade reagent, and the solution was mixed on a vortex mixer for 5s. The mixture

was centrifuged for 10 minutes and the supernatant read at 500ηm was read by using water as

a blank.

� Tannin analysis

Tannin content was determined by the method of Burns (1971) as modified by Maxson and

Rooney (1972). About 2.0 gram of anchote flour was weighed in a screw cap test tube. The

anchote flour was extracted with 10ml of 1% HCl in methanol for 24 hours at room

temperature with mechanical shaking. After 24 hours shaking, the solution was centrifuged at

1000rpm for 5 minutes. About 1ml of supernatant was taken and mixed with 5 ml of vanillin

HCl reagent (prepared by combining equal volume of 8% concentrated HCl in methanol and

4% vanillin in methanol).

D-catechin was used as standard for condensed tannin determination. A 40mg of D-catechin

was weighed and dissolved in 1000 ml of 1% HCl in methanol, which was used as stock

solution. A bout 0, 0.2, 0.4, 0.6, 0.8 and 1 ml of stock solution was taken in test tube and the

volume of each test tube was adjusted to 1ml with 1% HCl in methanol. About 5ml of

Page 39

vanillin HCl reagent was added into each test tube. After 20 minutes, the absorbance of

sample solutions and the standard solution were measured at 500nm by using water to zero

the spectrophotometer, and the calibration curve was constructed from the series of standard

solution using SPSS-15. A standard curve was made from absorbance versus concentration

and the slope and intercept were used for calculation. Concentration of tannin was read in mg

of D-catechin per 100gm of sample

Tannin in mg/100g = ……………………….. (3.13)

� Oxalate analysis

The oxalate content was determined using the method originally employed by Ukpabi and

Ejidoh (1989). The procedure involves three steps: digestion, oxalate precipitation and

permanganate titration.

• Digestion: At this step, about 2 g (db) of flour was suspended in 190 ml of distilled water

contained in a 250-ml volumetric flask; 10 ml of 6M HCl was added and the suspension

digested at 1000C for 1 h, followed by cooling, and then made up to 250 ml before

filtration.

• Oxalate precipitation: Duplicate portions of 125 ml of the filtrate were measured into a

beaker and four drops of methyl red indicator added, followed by the addition of

concentrated NH40H solution (drop wise) until the test solution changed from its salmon

pink colour to a faint yellow colour (pH 4-4.5). Each portion was then heated to 900C,

cooled and filtered to remove precipitate containing ferrous ion. The filtrate was again

heated to 900C and 10 ml of 5% CaCl2 solution was added while being stirred constantly.

After heating, it was cooled and left overnight at 5°C. The solution was then centrifuged

at a speed of 2500 rev/min for 5 min. The supernatant was decanted and the precipitate

completely dissolved in 10 ml of 20% (v/v) H2SO4, solution.

• Permanganate titration: At this point, the total filtrate resulting from digestion of 2 g of

flour was made up to 300 ml. Aliquots of 125 ml of the filtrate were heated until near

boiling, and then titrated against 0.5M standardized KMnO4, solution to a faint pink

Page 40

colour which persisted for 30 s. The calcium oxalate content was calculated using the

formula.

Oxalate (mg/100g) = ……………………………………… (3.14)

Where, T is the titre of KMnO4 (ml), Vme is the volume - mass equivalent (i.e. that 1 cm

3 of

0.05 M KMnO4, solution is equivalent to 0.00225 g anhydrous oxalic acid), DF is the

dilution factor VTA (2.4, where VT is the total volume of filtrate (300ml) and A is the

aliquot used (125 ml)), ME is the molar equivalent of KMnO4

in oxalate and mf is the mass

of flour used.

� Cyanide analysis

The cyanide content of the raw and differently processed anchote flours (boiled and

fermented and roasted) samples was determined by (AOAC, 1995). About 20 g of anchote

flour sample was placed in extraction flask and followed by addition of 100 ml of distilled

water and allowed to stand for two hours, in order to set free all the bound hydrocyanic acid,

meanwhile keeping the flask connected with an apparatus for distillation. After two hours of

maceration, 100 ml of distilled water was added to the slurry and steam distilled. The

distillate was collected in 20 ml 0.01N AgNO3

that has been acidified with 1 ml HNO3. The

distillation process was allowed to proceed for 40 minutes with vigorous boiling. After

passing over of 150 ml of the distillate, the distillate was filtered through Gooch with little

water and the excess AgNO3

was titrated in combined filtrate and washings with 0.02N

KSCN, using ferric alum indicator. The end point of titration was indicated by appearance of

faint reddish color up on addition of 0.02 N KSCN solution. The quantity of HCN present in

the sample was calculated from the following relation.

Volume (ml) of AgNO3 consumed to complex CN

-= 20 – 2 × Volume of the titere ….. (3.15)

1ml 0.01 N AgNO3 = 0.27 mg HCN …………………………………………………… (3.16)

Page 41

3.4.5 Sensory value analysis

Color, taste, flavor, crispness and overall acceptability of all the biscuits including the control

were evaluated by method using a 9 point Hedonic Scale (Giami et al, 2006).

Panelists were trained in the use of sensory evaluation procedures and the meaning of the

descriptive terms used. Panelists were instructed to evaluate color first and then to taste each

sample to evaluate flavor, crispness and overall acceptability. A nine point hedonic scale

with 1 = dislike extremely, 5 = neither like nor dislike, 9 = like extremely was used (Giami,

et al, 2006). Water was provided to rinse the mouth between evaluations and covered

expectoration cups were also provided when panelists didn’t wish to swallow the samples.

3.5 Experimental design and statistical analysis of data

A simple comparative experiment was designed for the study. The experiment was

completely randomized design (CRD). The study considered processing methods as one

factor with three levels of treatments (boiling, roasting and fermentation) to see their effects

on the proximate composition, ANF, physicochemical and functional properties of raw

anchote flour and one factor namely blend proportions with three levels of treatment to see

their effects on the quality of biscuits.

All analysis was done in triplicates. The results of the three replicates were taken and

expressed as mean ± standard deviation. A one-way analysis of variance (ANOVA) and the

least significance difference (LSD) were carried out using JMPIN 5.0.1 software to compare

the difference between treatment means. Significance difference was accepted at 0.05 level

of probability (P < 0.05).

3.6 Techno-economic feasibility analysis

� Material and energy Balance

Material and energy balance for the production of anchote flour and anchote-wheat flour

biscuit product were carried out based up on the generated laboratory data and by considering

the assumptions, that the plant has a capacity of 1500 ton per year and the plant operates for

300 days in a year.

Page 42

� Economic analysis

The total capital investment for the production of biscuit product was estimated by summing

up the fixed capital investment (FCI) and working capital. The working capital was taken as

15% of the fixed capital investment which is commonly used.

The total production cost for the production of biscuit product was estimated by summing up

the manufacturing cost and general expenses.

Unit product cost was evaluated by dividing the total product cost to the total plant capacity

per year.

Rate of return (ROR): the rate of return on investment for the production of biscuit product

was calculated by using the following equation;

Rate of return (ROR) = (Net profit/ total capital employed) ×100%

Payback period: The time required to return the allocated total investment for the production

of biscuit were calculated by using the equation;

Payback period (PBP) = (Fixed Capital Investment) / (Net profit + Depreciation)

Break – even analysis: the break-even production is the number of units necessary to produce

and sell in order fully to cover the annual fixed costs. It was computed as:

Total product cost = Total income

Break-even point =

Vcup = Variable costs per unit of production

Sup = Selling price per unit of production

Page 43

CHAPTER FOUR

RESULTS AND DISCUSSIONS

In this chapter the outcome of, proximate composition, mineral composition, functional

properties, the physicochemical properties and the levels of antinutritional factors of the raw

and processed anchote flours of the two samples were discussed. Table 4.1, 4.2, 4.3, 4.4, and

4.5, show the results of proximate composition, the mineral composition, the levels of

antinutritional factors, physicochemical and functional properties for raw and processed

anchote flour samples, respectively. Additionally the nutritional and sensory evaluation of

anchote-wheat flour composite biscuit is also discussed. All results were based on dry weight

basis of anchote flour.

(a) (b)

Figure 4.1 Samples of anchote tuber, a) Nekemte sample, b) Dembiddollo sample

4.1 Proximate and mineral composition of anchote flour

� Crude Protein

The protein content of raw and processed anchote flour samples collected from Nekemte

regions were in the range of 6.78% and 10.68%. The fermented sample (NF) had highest

protein value (10.68%) and the minimum corresponds to boiled samples of anchote (6.78%).

The protein percentage of the raw and roasted samples were 7.28 (3.00%, wwb) and 7.13%

respectively. The results showed that fermentation significantly (P < 0.05) increased the

protein content of the anchote sample by 46.9%. Boiling and roasting on the other hand had

Page 44

no significant effect (P > 0.05) on the protein content of the Nekemte anchote sample. The

result in raw Nekemte anchote was in agreement with the finding of Habtamu and Kelbessa

(1997) reported the raw anchote tuber contained 3.0g/100g crude protein (wwb). EHNRI also

reported that raw anchote contained 3.2% crude protein (wwb). Recently, Habtamu Fekadu

(2011) reported a protein content of 3.25 and 3.14% (wwb) for raw and boiled samples of

anchote, which agrees with the present finding.

The results of crude protein of the Dembidollo sample were in the range of 4.50 and 8.32%.

The maximum protein content was observed for the fermented sample (DF) and the

minimum for boiled anchote (DB). The protein content of raw Dembidollo (DR) anchote was

found to be 5.17% (2.1%, wwb) and roasted anchote sample (DRD) had a protein content of

4.68%. The crude protein content of the raw anchote sample of Dembidollo sample was

lower than the values reported by EHNRI, 1997(crude protein: 3.2%, wwb) and Habtamu and

Kelbessa, 1997(crude protein: 3.0%, wwb). In the Dembidollo sample it was observed that

among the three processing methods only fermentation had a significant effect (P < 0.05) on

the protein content of Dembidollo anchote flour sample, which was increased the crude

protein content by 60.9%. Similarly, Habtamu Fekadu (2011) reported that boiling had no

significant effect on the protein content of anchote. The increase in the protein content of

anchote flour during fermentation may be because some microorganisms such as micro-

fungi, which degrade anchote flour readily (Reade and Gregory, 1975), could have secreted

some extracellular enzymes (protein) in the anchote flour which can be possible reason for

the increase in the percentage of protein content in both samples. The decrease of

carbohydrate by fermentation and increase of carbohydrate by boiling contributes

proportionally to the increase and decrease of protein by fermentation and boiling

respectively as the values of all proximate analysis was computed out of hundred percent. It

is known that fermentation may enrich foods in protein by removing part of the fermentable

carbohydrate as documented in fermented foods made from cassava (Okafor 1998).In the

result higher protein content of anchote was recorded, it is evident that anchote crop contains

higher amount of protein content than any other crop (Abera, 1995). The mean values also

showed that there was a significant difference between the two samples of anchote collected

from different regions. From the result, it was shown that Nekemte anchote had higher

protein content in preference to the Dembidollo anchote sample.

Page 45

� Crude fat

The crude fat compositions of the two anchote flour samples are displayed in the table 4.1.

The table shows that the fat content of raw and processed anchote flour sample from

Nekemte were in the range of 0.6% (for NRD) and 1.32% (for NF). The value of raw

Nekemte (NR) sample was determined to be 1.15% (0.47%, wwb) and boiled anchote (NB)

had 0.78%.

On the other hand as shown in the table that the fat content for the raw and processed

Dembidollo flour sample were 0.59%, 0.88% (0.36% , wwb), 0.42% and 1.10% for DB, DR,

DRD and DF respectively. Maximum value was recorded for the fermented and minimum for

the roasted flour sample. The results show that the raw flours of both samples had higher fat

contents in compared to the results reported for raw anchote flour sample by Agren and

Gibson, 1968 (0.1%, wwb), EHNRI, 1997 (0.1%, wwb) and Habtamu and Kelbessa

,1997(0.17%, wwb) and Habtamu Fekadu, 2011 (0.19%, wwb). All three processes had a

significant effect (P < 0.05) on the fat content of both samples. An increase in fat content

during fermentation for both samples could be attributed to the possibility that, the fermenter

organisms could secrete microbial oil (Oboh and Akindahunsi, 2003). There was also a

significant difference between the fat content of the two samples. Higher fat content was

observed for Nekemte anchote sample than Dembidollo sample. Boiling significantly

reduced the crude fat content. It was indicated that boiling significantly reduced the crude fat

content of anchote flour (Habtamu Fekadu, 2011). The observed reduction in the fat content

of anchote flour during boiling is due to the leaching into boiling water (Ukwuru, 2003).

� Crude fiber

The crude fiber contents of the raw and processed Nekemte anchote flour sample are shown

in table 4.1, which were found to be 3.94% (1.6% , wwb), 4.67%, 2.82% and 2.83% for NR,

NB, NRD and NF, respectively. These values showed that boiling increased significantly (P

< 0.05) the crude fiber content. In contrast to boiling, roasting and fermentation significantly

(P < 0.05) reduced the fiber contents of the Nekemte anchote flour sample. The percentage

compositions for the crude fiber contents of the Dembidollo anchote flour sample were

between 3.67 and 5.78%. The maximum was for boiled sample (DB) and the minimum for

Page 46

roasted anchote (DRD). Fermented sample (DF) had 3.75% crude fiber and raw sample (DR)

4.73% (1.93%, wwb) crude fiber content. All three processes affected significantly (P < 0.05)

the crude fiber content in Dembidollo sample. Boiling significantly (by 22%) increased the

crude fiber content of the Dembidollo sample. Roasting and fermentation significantly

reduced the crude fiber content of the anchote sample from Dembidollo by 23 and 21%

respectively. The values for raw anchote of the two samples were in agreement with the

value reported by Agren and Gibson, 1968 (1.7%). But, the findings of Habtamu and

Kelbessa, 1997 (0.6%, wwb) and EHNRI, 1997 (0.7%, wwb) in crude fiber content of raw

anchote had lower crude fiber values. But, Habtamu Fekadu (2011) reported higher crude

fiber contents (2.58%, wwb). The decrease in fiber content of raw anchote flour of both

samples during fermentation is attributed to the possibility that the fermenter micro-

organisms could secrete hydrolytic enzymes (Oboh, 2005). These enzymes are capable of

hydrolyzing crude fiber into simple sugars, which the organism could use as its carbon

source and change it to other macromolecules or metabolites such as protein and fat (Oboh,

2006). The increment in crude fiber during boiling could be due to the fact that as samples

were subjected to boiling, and thus all the soluble components might have lost in the process

thereby increasing the crude fiber contents ( Ahmed et al., 2010).

� Ash

The results of ash values displayed in the table 4.1 shows that the ash percentage of the

sample collected from Nekemte regions had variation from 3.27 to 4.21 which corresponding

to NB and NF respectively. The percentage of ash for NRD and NR was 3.64% and 3.96%

(1.60%, wwb) respectively. The maximum and minimum ash content in Nekemte sample

was 4.21% and 3.27% respectively. Based on the findings, boiling and roasting processes

significantly (P < 0.05) reduced the ash content. Fermentation on the other hand significantly

(P < 0.05) increased the ash percentage. The decrease of carbohydrate and crude fiber

percentage by fermentation contributes proportionally to the increase of ash by fermentation

as the values of all proximate analysis was computed out of hundred percent. Contamination

from utensil during sample preparation and fermentation may also be the probable reason for

the increment in ash. The ash contents of Dembidollo sample were 4.67 (1.90%, wwb), 4.32,

3.86 and 4.54 for DR, DB, DRD, and DF respectively. All three processes significantly (P <

Page 47

0.05) reduced the ash values of the sample collected from Dembidollo region. The mean ash

content of raw anchote flours of Dembidollo sample was comparable to the findings of

Habtamu and Kelbessa, 1997 (2.00%, wwb) and Habtamu Fekadu, 2011 (2.19%, wwb). But

a lesser value was reported by EHNRI, 1997 and Agren and Gibson (1968) which was 1.10%

(wwb). Additionally, the ash percentage of raw sample of Nekemte was lower than the value

reported by Habtamu and Kelbesa (1997) and Habtamu Fekadu, 2011, but higher than the

report of EHNRI, 1997 and Agren and Gibson (1997). The reduction of total ash during

boiling and fermentation may be attributed due to leaching of mineral compound and water

absorption during boiling and fermentation (Lewu et al., 2009).

The observed difference in the ash contents between the two samples may be attributed to

climatic factor, the soil type, and the varietal and/or cultivar difference. From the high ash

contents of the anchote samples studied, one can easily understand that there would be

appreciable quantity of minerals in anchote.

� Moisture

The moisture determinations of the samples collected from Nekemte region ranged from 4.05

and 6.86 %. The maximum was for fermented sample (NF) and the minimum for roasted

sample (NRD) .Boiled sample (NB) had a moisture value of 5.78% and raw anchote (NR)

had a moisture content of 6.36%. The results of the moisture analysis for Demb idollo were

7.01% for DF, 6.60% for DR, 4.13% for DRD, 5.92% for DB. The determinations of

moisture for the two samples showed that boiling and roasting had a significant effect (P <

0.05) on moisture reduction of the two samples. Fermentation on the other hand significantly

(P < 0.05) increased the moisture content of both anchote samples.

In summary it seems that the moisture content for both samples in all treatments is in the

moisture range generally accepted for dry products in order to obtain a desirable shelf life of

the product (Sriroth et al., 2000).

� Utilizable carbohydrate

From the results of the study it could be observed that anchote is a very good source of

carbohydrate (CHO). The carbohydrate content of the Nekemte sample was 77.31% (27%,

Page 48

wwb), 78.72%, 81.76%, and 74.1% for NR, NB, NRD and NF respectively. Boiling and

roasting increased significantly (P < 0.05) the carbohydrate content while fermentation

reduced significantly (P < 0.05) the carbohydrate content of the sample. The reduction of

carbohydrate content by fermentation was around 4.2%. The sample from Dembidollo

regions had a carbohydrate content varied from 75.28 to 82.78 %. The least value, 75.28%

corresponds to fermented sample (DF) and the maximum was 82.78% and corresponds to

DRD sample. The raw sample (DR) had a carbohydrate content of 77.95% (27%, wwb) and

DB had a carbohydrate content of 79.35%. The result in raw anchote of the two samples were

higher than the finding of Habtamu and Kelbessa, 1997 (22.5%, wwb), EHNRI, 1967

(21.1%, wwb) and Agren and Gibson, 1968 (21.2%, wwb). Habtamu Fekadu (2011) reported

even lower CHO content (16.86%, wwb) and he also reported a significant reduction of CHO

contents during boiling, which contradicts to the present study.

In both samples, boiling has increased the carbohydrate content to some extent which results

from solubilization of starch which makes it much more available and increase in the

carbohydrate content of both samples (Tilahun et al. 2009). The possible basis for the

decrease in the carbohydrate of the fermented anchote flour of both samples will not be far

from the possibility that the micro-organisms could secrete hydrolytic enzymes (Oboh et al.,

2003; Oboh, 2005). These enzymes are capable of hydrolyzing carbohydrate into simple

sugars, such as maltose which the organism could use as its carbon source and changes it to

other macromolecules or metabolites such as protein and fat (Oboh and Akindahunsi, 2003;

Oboh,2006).

Page 49

Table 4.1 Proximate compositions of raw and processed anchote flour

Sample

Type

Protein (%) Fat (%) Fiber (%) Ash (%) Moisture

(%)

CHO (%) Energy

(Kcal/100g)

NR 7.28±0.320c 1.15±0.0436b 3.94±0.3387c 3.96±0.1609cde 6.36±0.1277c 77.31±0.2107f 348.71

NB 6.78±0.2623c 0.78±0.0458c 4.67±0.2750b 3.27±0.2330f 5.78±0.1967d 78.72±0.1153d 349.02

NRD 7.13±0.5205c 0.60±0.0557d 2.82±0.2551d 3.64±0.2615ef 4.05±0.1442e 81.76±0.1200b 360.96

NF 10.68±0.2007a 1.32±0.0361a 2.83±0.1587d 4.21±0.2400bcd 6.86±0.0917a 74.1±0.2498h 351.0

DR 5.17±0.4943d 0.88±0.0557c 4.73±0.1572b 4.67±0.3279a 6.60±0.0954b 77.95±0.1552e 340.4

DB 4.50±0.4355d 0.59±0.0458d 5.78±0.2910a 3.86±0.3064de 5.92±0.0794d 79.35±0.1200c 340.71

DRD 4.68±0.4818d 0.42±0.0265e 3.67±0.2193c 4.32±0.2358abc 4.13±0.0721e 82.78±0.4124a 353.62

DF 8.32±0.4600b 1.10±0.1153b 3.75±0.1931c 4.54±0.2107ab 7.01±0.1114a 75.28±0.2750g 344.3

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a column are not significantly different (P > 0.05)

Key: NR- Nekemte raw, DR-Dembidollo raw, NB -Nekemte boiled, DB-Dembidollo boiled, NRD-Nekemte roasted, DRD-Dembidollo roasted, NF-Nekemte

fermented, DF-Dembidollo fermented, a ,b ,c, d, e …. are superscripts given to show the significant difference between means, a > b > c > d….

All values are expressed in (g/100g) of dry weight basis of edible portion

Page 50

� Calcium

The calcium contents of Nekemte sample were 470.13 (164mg/100g, wwb), 464.12, 462.2

and 424.18mg/100g which correspond to NR, NB, NRD and NF respectively. The calcium

contents of Dembidollo sample were 549.009 (192mg/100g, wwb), 544.3, 541 and

501.1mg/100g for DR, DB, DRD and DF in the given order. The calcium contents of the raw

anchote from the two places were higher than the values reported by Agren and Gibson, 1968

(119mg/100g, wwb) and EHNRI, 1997 and Habtamu Fekadu, 2011(119mg/100g, wwb) and

lower compared with the results reported by Habtamu and Kelbesa, 1997 (344mg/100g ,

wwb). All three processes reduced significantly (P < 0.05) the calcium contents of the

anchote samples from the two places. Comparing the two samples of anchote the sample

from the Dembidollo had higher calcium content than the corresponding Nekemte sample.

The probable reason for the reduction of Ca during roasting may be antinutrients have

interfered with the bioavailability of Ca as suggested by Alonso et al. (2010) and Anigo et al.

(2009). The reduction during boiling and fermentation may be attributed to leaching out in

boiling and fermentation water. The reduction in Ca content during boiling agrees with

previous report of Habtamu Fekadu (2011). The probable reason for difference in Ca content

of the two samples may be due to difference in genetic origin, geographical source and soil

conditions of the samples collected.

� Iron

Sample of Nekemte had Fe content of 13.38 (5.5mg/100g, wwb), 14.85, 14.23 and 10.70

mg/100g for NR, NB, NRD and NF respectively. Sample from Dembidollo also contained Fe

content of 14.12mg/100g (5.8mg/100g, wwb) for DR, 15.63 mg/100g for DB, 15.12 mg/100g

for DRD and 12.34 mg/100g correspond to DF. The result in raw anchote of the two samples

was comparable with the finding of Habtamu and Kelbesa, 1997 and Habtamu Fekadu, 2011

(5.5mg/100g, wwb). However, EHNRI (1997) (1.3mg/100g, wwb) and Agren and Gibson,

1968 (1.8mg/100g, wwb) reported lower iron contents. Boiling and roasting increased

significantly (P < 0.05) the Fe content, but fermentation reduced the Fe content significantly

(P < 0.05). The Fe increment during boiling could be due to contamination from cooking

utensils (Akin-Idowu et al., 2009). A significant increase in Fe content during boiling of

anchote was also reported by Habtamu Fekadu, 2011.

Page 51

� Zinc

The mean values of zinc content of the Nekemte sample were 6.43 mg/100g (2.64mg/100g,

wwb), 5.34 mg/100g, 6.31mg/100g and 7.63mg/100g for the corresponding NR, NB, NRD

and NF respectively. Dembidollo anchote had zinc content values varied from 5.29 to

7.42mg/100g. The minimum corresponds to DB and the maximum to DF. The raw sample

(DR) had a Zn content of 6.37mg/100g (2.61mg/100g, wwb) and DRD had a value

6.28mg/100g. Boiling reduced significantly (P < 0.05) zinc content, while fermentation

increased significantly (P < 0.05) zinc content. No significant (P > 0.05) difference was

observed between the two samples in zinc content. The results of zinc content of the raw

anchote samples were higher than the report of Habtamu and Kelbessa, 1997 (1.8mg/100g,

wwb) and Habtamu Fekadu, 2011 (2.23mg/100g, wwb). The probable reason for the

reduction of zinc during boiling may be attributed to leaching out of Zn in boiling water.

� Potassium

The results in the table 4.2 show that the K contents of Nekemte sample were between

1252.23 and 1468.42mg/100g. The minimum K content corresponds to NB and the

maximum belongs to NF. NR and NRD had a K content of 1293.75mg/100g and

1256.9mg/100g respectively. The K contents of Dembidollo sample were 1562.50, 1511.56,

1516.2, and 1745.1mg/100g for the corresponding DR, DB, DRD and DF respectively. The

results show that boiling and roasting reduced the K content of anchote collected from the

two places significantly (P < 0.05). But, Fermentation process increased the K content

significantly (P < 0.05) in both samples. The potassium salts present in the nutrient solution

could have caused this increase in K content (Oboh G. and Elusiyan C. A.). The results also

showed the K contents of the two anchote samples were significantly (P < 0.05) different,

this may be due to varietal difference, environmental factors and soil type as the two samples

were collected from different places. Very high amount of K contents were recorded in both

samples.

Page 52

Table 4.2 Mineral compositions of raw and processed anchote flour

Sample

Type

Ca

(mg/100g)

Fe

(mg/100g)

Zn

( mg/100g)

K

(mg/100g)

NR 470.13±1.0709e 13.38±0.4491e 6.43±0.4386b 1293.75±1.0371f

NB 464.12±0.9498f 14.85±0.5386bc 5.34±0.3576c 1252.23±1.0697h

NRD 462.2±1.5037f 14.23±0.3143cd 6.31±0.3342b 1256.9±0.7669g

NF 424.18±1.1067g 10.70±0.4328g 7.63±0.4371a 1468.42±1.1761e

DR 549.00±1.0106a 14.12±0.3676d 6.37±0.4161b 1562.50±1.2371b

DB 544.3±0.9849b 15.63±0.2987a 5.29±0.4314c 1511.56±0.9364d

DRD 541±0.9297c 15.12±0.2787ab 6.28±0.3751b 1516.2±0.9983c

DF 501.1±1.3647d 12.34±0.4258f 7.42±0.3372a 1745.1±0.9450a

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a row are not significantly different (P>0.05)

Key: NR- Nekemte raw, DR-Dembidollo raw, NB -Nekemte boiled, DB-Dembidollo boiled, NRD-Nekemte

roasted, DRD-Dembidollo roasted, NF-Nekemte fermented, DF-Dembidollo fermented, Ca-calcium, Fe-iron,

Zn-zinc, K-potassium, a, b, c, d, e …. are superscripts given to show the significant difference between means, a

> b > c > d….

All values are expressed in (mg/100g) of dry weight basis of edible portion

4.2 Antinutritional factors of anchote flour

Anti-nutrients are known to reduce the maximum utilization of nutrients especially proteins,

vitamins and minerals (Ugwu and Oranye, 2006). So that, the levels of ant-nutritional factors

in the anchote tubers are important in the assessment of its antinutritional status. The contents

of antinutritional factors, phytate, tannin, oxalate and cyanide of the raw and processed

anchote tuber is shown in table 4.3.

4.2.1 Phytate

The phytate contents obtained in the two anchote samples are indicated in table 4.3. The

levels of phytate in anchote flour prepared from Nekemte sample ranged from 9.34mg/100g

to 20.65mg/100g. The phytate content for NR was 20.65mg/100g and for fermented Nekemte

anchote (NF) the phytate level was 9.34mg/100g. The phytate level of the boiled (NB) and

roasted Nekemte (NRD) anchote were 14.54 and 13.67mg/100g respectively. The phytate

Page 53

level in Dembidollo sample ranged from 11.45 mg/100g to 33.06 mg/100g, where the

intermediate levels were 22.21 mg/100g for DB and 21.65mg/100g for DRD. All three

processes reduced significantly (P < 0.05) the phytate content in both samples. In both

samples fermentation had a more significant implication on the reduction which reduced the

phytate by 55 and 65% in Nekemte and Dembidollo samples respectively. There was also a

significant difference between the two anchote samples. The sample collected from Nekemte

regions had lower phytate level in comparison to sample collected from Dembidollo region.

The possible reason for the decrease in phytate content during fermentation and boiling may

be partly due to leachching out of phytate with boiling and fermentation water and either to

the formation of insoluble complexes between phytate and other components, such as

phytate-protein and phytateprotein– mineral complexes or to the inositol hexaphosphate

hydrolyzed to penta- and tetraphosphates (Siddhuraju and Becker, 2001). The decrease in the

phytate content of the fermented anchote flour for both samples could possibly be attributed

to the secretion of the enzyme phytase. This enzyme is capable of hydrolyzing phytate (Oboh

et al., 2003), thereby decreasing the phytate content of the anchote flour. The Phytate content

reported by (Habtamu Fekadu, 2011), which is 389.3mg/100g for raw anchote and

334.74mg/100g for boiled anchote sample is drastically higher than the phytate concentration

determined in the present study. The Phytate concentration range obtained in the present study is

lower compared to the acceptable concentrations. In average, the daily intake of phytate was

estimated to be 2000–2600 mg for vegetarian diets as well as diets of inhabitants of rural

areas of developing countries and 150–1400 mg for mixed diets (Reddy NR, 2002). But,

Hurrel, R. F et al. (1992) reported that phytic acid intake of 4-9mg/100g is said to decrease

iron absorption by 4-5 folds in humans.

4.2.2 Tannin

Tannins affect nutritive value of food by forming a complex with protein (both substrate and

enzyme) thereby inhibiting digestion and absorption (Oboh and Elusian, 2007). The tannin

determinations of the two samples of anchote flour are shown in table 4.3. The levels of

tannin for Nekemte sample were given 50.19mg/100g, 21.76 mg/100g, 19.82 mg/100g and

13.87 mg/100g for NR, NB,NRD and NF respectively and these values showed that the total

tannin content was the highest for NR (50.19 mg/100g) which was control or unprocessed

Page 54

sample, and minimum for NF (13.67 mg/100g). All three processes reduced significantly (P

< 0.05) the tannin content in Nekemte sample. Fermentation reduced the tannin content

approximately by 73%. The tannin content for anchote flour of Dembidollo sample varied

between 16.23 mg/100g and 56.34 mg/100g, which referred to DF and DR as the minimum

and maximum determinations respectively. The tannin content of DB was 26.73mg/100g and

the tannin content for DRD was 22.45mg/100g. A significant (P < 0.05) reduction of tannin

content was observed in all three processes, where the maximum reduction was observed by

fermentation process (71% reduction). The levels of tannin between the two samples were

differed significantly (P < 0.05). Dembidollo sample contain higher level of tannin than the

corresponding Nekemte sample. The decrease in the levels of tannin during boiling and

roasting might be due to thermal degradation and denaturation of the antinutrients as well as

the formation of insoluble complexes and leaching out of hydrolysable tannin in the boiling

water (Kataria et al., 1989). Reduction in tannin contents due to fermentation might have

been caused by the activity of polyphenoloxidase or tanniase of fermenting microflora on

tannins (Fagbemi et al., 2005). The tannins content of anchote flour in this study is quite less

than the tannins content reported by (Habtamu Fekadu, 2011). Anchote flour samples from

the two regions could be considered safe with regard to tannin, since the tannin content is far

below the total acceptable tannin daily intake for man, 560mg (Anonymous, 1973).

4.2.3 Oxalate

The results for oxalate analysis of the raw and processed samples of anchote indicated that

the levels of oxalate in Nekemte sample ranged in between 2.45 and 6.56mg/100g. Raw

sample (NR) had oxalate content of 6.56mg/100g and the fermented sample (NF) had

2.45mg/100g oxalate content. The oxalate contents of NB and NRD were 4.21 and

3.65mg/100g respectively. The oxalate content of the samples collected from Dembidollo

regions were 7.32, 4.13, 3.74, and 2.67 in mg/100g for DR, DB, DRD, and DF respectively.

All three processes reduced significantly (P < 0.05) the oxalate content in both samples. The

maximum oxalate reduction was observed by fermentation, which was 63% for both samples.

Fermenting and boiling may cause considerable cell rupture and facilitate the leakage of

soluble oxalate into fermenting and cooking water (Albihn and Savage, 2001). The oxalate

content of the present study is comparable to the oxalate content recorded by (Habtamu

Page 55

Fekadu, 2011) which is 8.23mg/100g for raw anchote sample and 4.66mg/100g for boiled

anchote sample. The lethal level of oxalate in man is 3-5g as reported by Balogoplan C., et

al. (1998), so the oxalate levels of anchote samples in the present study is very low, which

will not result a serious harm.

4.2.4 Cyanide

Cyanide either in synthetic inorganic forms as in KCN or NaCN, or organic forms as in

cyanogenic glucosides, is a potent specific inhibitor of several enzyme-catalyzed processes

(Aletor, 1993). The results of cyanide levels are displayed in table 4.3. For Nekemte sample

the determinations were 5.32, 4.39, 4.03 and 2.78mg/100g for NR, NB, NRD, and NF

respectively. All processes reduced significantly (P < 0.05) the cyanide level. The maximum

cyanide reduction was 48% by fermentation for Nekemte sample.

The cyanide levels for the corresponding anchote sample from Dembidollo were

6.06mg/100g for DR, 4.22mg/100g for DB, 4.6mg/100g for DRD and 3.01mg/100g for DF.

Again with Dembiollo sample all the three processes reduced significantly (P < 0.05) the

cyanide. The maximum reduction of cyanide for dembidollo sample was by fermentation and

it was 50%. The results obtained showed that the processed anchote tuber could be

considered safe with regard to cyanide poisoning due to the fact that the cyanide levels were

far below the detrimental levels of 50 to 200mg (Kingsbury, 1964). The cyanide

concentration in the present study is lower than the report of Habtamu Fekadu (2011), who

recorded 12.67mg/100g for raw anchote and 11.14mg/100g for boiled anchote sample.

Page 56

Table 4.3 Antinutritional factors of raw and processed anchote flour

Sample

Type

Phytate

(mg/100g

Tannin

(mg/100g)

Oxalate

(mg/100g)

Cyanide

(mg/100g)

NR 20.65±0.4257c 50.19±0.2179b 6.56±0.3219b 5.32±0.2706b

NB 14.54±0.2931d 21.76±0.3483e 4.21±0.2358c 4.39±0.3764c

NRD 13.67±0.3451e 19.82±0.3341f 3.65±0.4004d 4.03±0.3439c

NF 9.34±0.2893h 13.87±0.2835h 2.45±0.2910e 2.78±0.4875d

DR 33.06±0.1513a 56.34±0.2498a 7.32±0.2787a 6.06±0.1513a

DB 22.21±0.2718b 26.73±0.2163c 4.13±0.2651cd 4.22±0.3940c

DRD 21.65±0.5011b 22.45±0.3439d 3.74±0.1868cd 4.6±0.4371c

DF 11.45±0.3242g 16.23±0.2910g 2.67±0.2464e 3.01±0.4687d

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a column are not significantly different (P>0.05)

Key: NR- Nekemte raw, DR-Dembidollo raw, NB -Nekemte boiled, DB-Dembidollo boiled, NRD-Nekemte

roasted, DRD-Dembidollo roasted, NF-Nekemte fermented, DF-Dembidollo fermented, a,b,c,d,e …. are

superscripts given to show the significant difference between means, a > b > c > d….

All values are expressed in (mg/100g) of dry weight basis of edible portion

4.3 Physicochemical properties of anchote flour

The physicochemical properties of raw and processed anchote flours are presented in Table

4.4. All results except peel percentage are based on dry weight basis of edible portions of

anchote.

• Tuber size and peel percentage

The average tuber sizes of both samples were determined .The average tuber sizes of

Nekemte sample were from 50.5 to 324g and the sample collected from Dembidolo regions

were in the range of 55.6 to 315g. The peel percentage was determined and it was 6.1 and

6.2% on wet weight basis for Nekemte and Dembidollo samples respectively.

Page 57

• pH value

Table 4.4 shows the results of PH values of the raw and processed anchote of the two

samples. The PH for Nekemte anchote was in the range of 4.7 and 6.2 where as that of

Dembidolo varied between 4.8 and 6.4. For Nekemte sample the maximum PH value

corresponded with NR and NB (6.2) and the minimum PH value belonged to NF (4.7) while

the NRD (5.6) had intermediate PH value. Roasting and fermentation had a significant effect

(P < 0.05) on the PH value of Nekemte sample. Boiling had no significant effect (P > 0.05)

on the PH values of Nekemte sample. For Dembidolo sample the PH values were DR (6.4),

DB (6.3), DF (4.8) and DRD (5.6). From the result it was observed that all the three

processing had a significant effect (P < 0.05) on the PH values of the Dembidolo flour

sample of anchote. Fermentation reduced the PH values of both samples by 25%; this is due

to the fact that during fermentation some of the sugar present in anchote is converted to

acids. Acid production during anchote fermentation might be attributed to the activities of the

lactic acid bacteria on the carbohydrates of the anchote root (Oyewole, 1990) that results in

the formation of lactic acid and formic acid where the formation of these acids in turn

increases the rate of acid tolerant microorganisms such as Geotriccum Candida that converts

lactic acid in to aldehydes and eaters developing a product of good aroma and flavor due to

the formation of these organic compounds.

• Titratable acidity

The titratable acidity values of the raw and processed Nekemte sample, which are expressed

as percentage of lactic acid in the sample, ranged of 0.182 and 0.358%, where the lower

value belonged to the raw Nekemte anchote sample and the higher for the fermented sample.

The titratable acidity of NB and NRD were 0.187 and 0.270% respectively. With the same

trend the titratable acidity for the Dembidolo samples were between 0.114 and 0.323%.

Again the maximum (0.323%) was for fermented sample and the minimum (0.114%) for raw

Dembidollo sample. The values for DB and DRD were 0.145 and 0.236% respectively. All

the three processes had a significant effect (P < 0.05) on the titratable acidity of both

samples. Fermentation had a more significant effect on titratable acidity of both anchote

samples than other processing methods, which is evident that fermented foods have higher

lactic acid content and lower PH values.

Page 58

• Water activity

The results for the water activity of the flours of anchote are displayed in table 4.4. The

anchote sample from Nekemte had values ranged from 0.390 to 0.492.The maximum value

was for NF and the minimum for NB. The water activity of NR was 0.406 and NRD had a

water activity of 0.466. All processing methods had a significant effect (P < 0.05) on the

water activity of Nekemte flour sample. In Dembidollo anchote sample the water activity

values varied from 0.415 to 0.502. Again the maximum corresponded to DF and the

minimum to DB. The water activities of DR and DRD were 0.480 and 0.487 respectively.

The Dembidolo samples were affected significantly (P < 0.05) by the three processing

methods.

Table 4.4 Physicochemical properties of raw and processed anchote flour

Sample

Type

Properties

PH Tuber

Size(g)

Peel percentage

(%), wwb

Water Activity Titratable Acidity

(%)

NR 6.2±0.1b 50.5-324 6.1 0.406±0.0031f 0.182±0.0021cd

NB 6.2±0.1b x x 0.390±0.0030g 0.187±0.0099c

NRD 5.6±0.1c x x 0.466±0.0031d 0.270±0.0076b

NF 4.7±0.1d x x 0.492±0.0025b 0.358±0.0111a

DR 6.4±0.2a 55.6-315 6.2 0.480±0.0040c 0.114±0.0098e

DB 6.3±0.1b x x 0.415±0.0025e 0.145±0.0115de

DRD 5.7±0.1c x x 0.487±0.0040b 0.236±0.0164b

DF 4.8±0.1d x x 0.502±0.0035a 0.323±0.0575a

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a column are not significantly different (P > 0.05)

Key: NR- Nekemte raw, DR-Dembidollo raw, NB -Nekemte boiled, DB-Dembidollo boiled, NRD-Nekemte

roasted, DRD-Dembidollo roasted, NF-Nekemte fermented, DF-Dembidollo

a, b, c, d, e …. are superscripts given to show the significant difference between means, a > b > c > d….

All values are expressed in dry weight basis except peel percentage

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4.4 Functional properties of anchote flour

Functional properties of both raw and processed anchote flours obtained from the two

different places used in this study were determined. Table (4.5) shows the values of the

different functional properties. These are bulk density, water and oil absorption capacity,

foaming capacity, foaming stability, swelling power and solubility index.

� Bulk density

The bulk density of flour is important in relation to its packaging. The results of the bulk

density for the two flour samples are displayed in table 4.5. The bulk density values for the

anchote flour samples collected from Nekemte regions were 0.73, 0.75, 0.83,0.83 in g/ml for

NR, NF, NRD and NB respectively. These values shows that boiling and roasting had a

significant effect (P < 0.05) on the bulk densities of the Nekemte anchote flour and

fermentation had no significant effect (P > 0.05). Boiling and roasting increased significantly

(P < 0.05) the bulk density of Nekemte flour sample. For the anchote flour sample collected

from Dembidollo the values were in the range of 0.69 to 0.90g/ml. The maximum value

0.90g/ml belongs to DRD and the minimum value (0.69) corresponds to DR. DF and DRD

had values of 0.72g/ml and 0.78g/ml respectively. The results show that all the three

processing methods had a significant effect (P < 0.05) on the bulk density of Dembidollo

anchote flour. Generally anchote flour sample of Nekemte regions have higher bulk density

than anchote flours collected from Dembidollo regions. Having higher bulk density is an

advantage because it takes less packaging materials and hence less cost of packaging. Plaami

(1997) reported that bulk density is influenced by the structure of the starch polymers and

loose structure of the starch polymers could result in low bulk density. Bulk density is very

important in determining the packaging requirement, materials handling and application in

wet processing in the food industry (Karuna et al., 1996).

� Water absorption capacity

The water absorption capacity of raw and processed flours the two anchote samples is

presented in table 4.5. The water absorption capacity of anchote flour of Nekemte sample

ranged from 1.88 to 1.97ml/g which belonged to NF and NB representing the lowest and the

highest determinations respectively. The WAC of raw sample (NR) and roasted sample

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(NRD) were 1.93ml/g and 1.94ml/g respectively. The results shows that all three processes

had a significant effect (P < 0.05) on water absorption capacity of Nekemte anchote samples.

The water absorption capacity of Dembidolo samples ranged from 1.92 to 2.51ml/g which

belong to DF and DB samples, respectively. The raw sample, DR had a water absorption

capacity value of 2.19 ml/g and DRD had a value of 2.34ml/g. For Dembidolo anchote flour

all three processes had a significant effect (P < 0.05) on the WAC of the flour. Water

absorption capacity describes flour – water association ability under limited water supply.

Water binding capacity is a useful indication of whether flour or isolates can be incorporated

into aqueous food formulations (Udensi and Okoronkwo, 2006). From the results it was

shown that the anchote samples collected from Dembidollo had higher water absorption

capacity than the Nekemte anchote samples. Boiling increase WAC is probably due to the

loose structure of starch and removal of fat exposes the water binding sites of amino acids

(Adebowale et al 2005, Oladopo and Nwokocha, 2011). The decrease in WAC during

fermentation could be attributed to the increment in fat content, as fat block the hydrophilic

sites of amino acids and CHO.

� Oil absorption capacity

Oil absorption capacity (OAC) is another important functional property since it plays an

important role in enhancing the mouth feel while retaining the flavor of food products

(Kinsella, 1976). It has been reported that variations in the presence of non-polar side chains,

which might bind the hydrocarbon side chains of oil among the flours, explain differences in

the oil binding capacity of the flours (Adebowale & Lawal, 2004). The oil absorption

capacity of the anchote flour is given in table 4.5. The table shows that the OAC of Nekemte

anchote samples ranged from 1.1 to1.82 ml /g where it was maximum for NB and minimum

for NR. OAC of NRD was 1.13ml/g and NF had OAC of 1.80ml/g. Boiling and fermentation

has a significant effect (P<0.05) on the OAC of Nekemte anchote flour. It was observed that

roasted sample had no significant difference (P > 0.05) to the OAC of the raw Nekemte flour.

The OAC of Dembidolo anchote flour was varied between 1.73 to 1.82ml/g for DR and DF

respectively. In this sample, the oil absorption was found to be highest for DF (1.82 ml/g)

and minimum for DR (1.73ml/g). All three processes had shown a significant effect (P <

0.05) on the OAC of the Dembidolo anchote flour. It was observed also that the OAC of both

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samples of anchote showed a greater OAC than cassava studied before (Tilahun A., 2009)

which was in the range of 0.65 to 1.5ml/g. Values reported by Adane T., 2009, for the other

root crop, taro (OAC 0.9 to 1.63ml/g) is also showed less OAC than observed here in anchote

samples. Oil absorption is an important property in food formulations because fats improve

the flavor and mouth feel of foods (Odoemela, 2005). The increase in OAC of anchote flour

during fermentation and boiling might be attributed to structural modifications of residual

starch and protein (Tjahjadic, Lins, Breen WM, 1988) and also the presence of non polar side

chains which might bind th hydrocarbons side chains of oil among the flours (Adebowale and

Luwal, 2004).

� Foaming capacity

The foamability is related to the amount of solubilized protein (Narayana and Narasinga Rao,

1984) and the amount of polar and non-polar lipids in a sample (Nwokolo, 1985). It is also

dependent on the configuration of protein molecules (D.E. Graham, and M.C. Philips, 1976).

The results showed that the foaming capacity values of the Nekemte sample were 4.07, 2.1,

3.5, and 4.97ml/g. The maximum value corresponds with NF and the minimum for NB. The

intermediate values, 4.07ml/g and 3.5ml/g belong to NR and NRD respectively. The foaming

capacities of the Dembidolo sample were 3.93, 3.5, 4.40, and 1.5ml/g for DR, DRD, DF, and

DB respectively. All processing methods had a significant effect (P < 0.05) on the foaming

capacity. Roasting and boiling reduced the foaming capacity significantly (P < 0.05). The

reason for the reduction of foaming capacity during roasting and boiling is due to the fact that

proteins are denatured irreversibly that results the lower protein content which in turn reduce

foaming capacity. Foam formation and stability are a function of the type of protein, pH,

processing methods, viscosity and surface tension (Yasumatsu et al., 1972). The increase and

decrease of the foam capacity is due to the increase and decrease of the protein content due to

the processing. The foamability of flours has been shown to be related to the amount of

native protein. Native protein gives higher foam stability than the denatured protein. It is

related to the amount of solubilized protein (Odoemelam, 2005). Soluble proteins in general

play an important role in the formation of foam and this probably justify why legumes

exhibit higher foaming capacity (Mbofung et al., 2006). On the other hand fermentation

process increased the foam capacities on both samples significantly (P < 0.05). The most

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probable reason for an increase in the foaming capacity of flour is due to an increase in the

percentage of protein content by fermentation process. The low foam capacity may be

attributed to the low protein content of the flour since foamability is related to the amount of

solubilized protein and the amount of polar and non-polar lipids in a sample (Nwokolo,

1985). It was also showed that the anchote sample collected from Nekemte had higher

foaming capacity in comparison with Dembidolo sample; this was due to the reason that the

Nekemte sample had higher protein content than the corresponding Dembidollo sample.

� Foam stability

The foaming stabilities of two samples of anchote flour are presented in table 4.5 and the

values ranged from 0.36 to 2.70ml/g for Nekemte sample. The maximum determination was

obtained for NF and the minimum determination was found to be for NB. NRD and NR have

values of 1.07 and 2.03ml/g respectively. The foaming stabilities of Dembidollo sample were

determined to be 1.13, 0.11, 0.26 and 2.35ml/g for DR, DB, DRD, and DF respectively.

From the result, it was shown that fermentation increased significantly (P < 0.05) but boiling

and roasting reduced significantly (P < 0.05) the foaming stability in both samples. Foam

stability is important since the usefulness of whipping agents depend on their ability to

maintain the whip as long as possible (Lin et al., 1974).

� Swelling power

The swelling powers of the two flour samples were in the range of 9.36 to 12.58g/g as shown

in table 4.5. The values for Nekemte anchote flour were between 9.36 and 10.93g/g. The

highest swelling power (10.93g/g) was recorded to NB and the minimum was recorded for

NF. NR and NRD had 10.59 and 10.68g/g swelling powers respectively. The results for

Dembidolo sample were 11.88g/g (RD), 10.58g/g (BD), 12.39g/g (DRD), and 10.01g/g (DF).

These values were greater compared with other root crop, cassava, reported by T.Abera

(2009) studied in Ethiopia. All the three processing had a significant effect (P < 0.05) on the

swelling power of both samples of anchote flour. Boiling and roasting methods increased

significantly (P < 0.05) the swelling power of the anchote sample collected from the two

different regions of Ethiopia. Fermentation significantly reduced the swelling powers of the

samples. Swelling powers of the two samples were significantly (P < 0.05) different.

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Dembidollo sample had higher swelling power than the Nekemte sample; this may be

attributed to the inhibitory action of lipid (fat) on water as Dembidollo samples had lower fat

content than Nekemte anchote samples (table 5.1). As swelling refers to absorption of water,

it may be inhibited by the lipid content of the flour (Hood et al., 1998). The swelling power is

an indication of presence of amylase which influences the quantity of amylose and

amylopectin present in the anchote flour. Therefore, the higher the swelling power, the higher

the associate forces (Ruales et al, 1993). The variation in the swelling power indicates the

degree of exposure of the internal structure of the starch present in the flour to the action of

water (Ruales et al, 1993). Boiling enhances the WAC of the flours and hence increases the

swelling powers, as swelling power of starch-based flour is related WAC of the flour during

heating (Loos et al 1981).

� Solubility index

The results of the solubility index for the two samples are displayed in table 4.5. From the

table it was observed that the solubility indexes for the Nekemte sample were between 15.30

and 48.10%. The maximum was for the NR and the minimum for NF. The other values were

NB (43.38%) and NRD (36.87%).The results of Dembidolo sample were 41.55% (DR),

54.23% (DB), 63.29 % (DRD), and 13.18% (DF). The maximum solubility index was

observed for the roasted Dembidollo (DRD) sample and fermented Dembidolo sample (DF)

had the least solubility index. It was observed that all processes had a significant effect (P <

0.05) on the solubility index of the two samples of anchote flours. Boiling and roasting

reduced significantly (P < 0.05) the solubility index of the Nekemte sample and increased

significantly (P < 0.05) the solubility index of Dembidollo sample. Fermentation reduced

significantly (P < 0.05) the solubility index of both samples. As a direct result of flour

swelling, there is a parallel increase in the solubility of flour (Onitilo et al., 2007). High

solubility implies high leaching. The high water solubility of any sample analyzed may be

attributed to the degree of swelling power and swelling power and solubility of the flour

provide evidence of non-covalent bonding between molecules within the flour (Rasper,

1969).

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Table 4.5 Functional properties raw and processed anchote flour

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a column are not significantly different (P>0.05)

NB: NR- Nekemte raw, DR-Dembidollo raw, NB -Nekemte boiled, DB-Dembidollo boiled, NRD-Nekemte roasted, DRD-Dembidollo roasted, NF-Nekemte

fermented, DF-Dembidollo fermented, Ca-calcium, Fe-iron, Zn-zinc, K-potassium, a, b, c, d, e …. are superscripts given to show the significant difference

between means, a > b > c > d….

All values are expressed in dry weight basis of edible portions of anchote

Sample

Type

Properties

BD(g/ml) WAC (ml/g) OAC(ml/g) Swelling

Power (g/g)

Solubility

Index (%)

Foam

capacity(ml/g)

Foam Stability

(ml/g)

NR 0.73±0.0185d 1.93±0.0058e 1.11±0.0223c 10.59±0.0010f 48.10±0.0208c 4.07±0.2082c 2.03±0.0757c

NB 0.83±0.0090b 1.97±0.0153d 1.82±0.0153a 10.93±0.0025d 43.38±0.2651d 2.10±0.1000f 0.36±0.1528e

NRD 0.83±0.0066b 1.94±0.0100de 1.13±0.0220c 10.68±0.0030e 36.87±0.0300f 3.5±0.1000d 1.07±0.0100d

NF 0.75±0.0085d 1.88±0.0100f 1.80±0.0100a 9.36±0.0030h 15.30±0.1539g 4.97±0.1528a 2.70±0.0100a

DR 0.69±0.0070e 2.19±0.0611c 1.73±0.0153b 11.88±0.0030c 41.55±0.0611e 3.93±0.1000c 1.13±0.0100d

DB 0.90±0.0148a 2.51±0.0100a 1.81±0.0153a 12.58±0.0010a 54.23±0.0902b 1.50±0.2000g 0.11±0.0100f

DRD 0.78±0.0108c 2.34±0.0300b 1.81±0.0208a 12.39±0.0030b 63.29±0.2138a 3.00±0.1000e 0.26±0.0100e

DF 0.72±0.0085d 1.92±0.0200ef 1.82±0.0153a 10.01±0.0031g 13.18±0.0513h 4.40±0.1528b 2.35±0.0643b

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4.5 Proximate and mineral compositions of anchote- wheat based biscuit

� Proximate compositions

The proximate compositions of the control biscuit and the 10% fermented anchote-wheat

blended biscuit (AWB1) selected based on high sensory acceptability were determined in the

analysis. The results are displayed in table 4.7 below. The protein contents were found to be

8.92% and 9.1% for the control biscuit (WB) and the blended biscuit (AWB1) respectively.

The fat percentage varied from 12.34 to 12.37% with incorporation of 10% fermented

anchote flour. The percentage compositions of ash were found to be 1.12 and 1.43% for WB

and AWB1 respectively. With the same trend the crude fiber content was between 0.34 and

0.59%. A significant (P < 0.01) increase of ash and crude fiber contents were observed with

10% substitution of wheat flour with anchote flour. This is due to the fact that anchote is

known for its higher mineral and crude fiber content (Table 4.1). But no significant effect on

protein and fat contents were observed between the two biscuits. The reason for no

significant difference of protein and fat contents was due to the fact that fermented anchote

and wheat flour had similar protein and fat contents.

Table 4.6 Proximate compositions of biscuit recipe

Constituents Fermented anchote flour Wheat flour

Protein 10.68±0.2007a 9.43±0.3831b

Fat 1.32±0.0361a 1.11±0.0324b

Crude fiber 2.83±0.1587a 0.51±0.05743b

Ash 4.21±0.2400a 1.07±0.0465b

Moisture 6.86±0.0917b 10.34±0.2578a

Carbohydrate 74.1±0.2498b 77.54± 0.2577a

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a row are not significantly different (P>0.05)

All values are expressed in dry weight basis of edible portions of anchote

Key: a, b, c, d, e …. are superscripts given to show the significant difference between means, a > b > c > d….

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Table 4.7 Proximate compositions of anchote- wheat based biscuit

Constituents Control

biscuit(WB)

AWB1

Protein 8.92 ± 0.1345a 9.1 ± 0.1513a

Fat 12.34 ± 0.4521a 12.37 ± 0.3315a

Ash 1.12 ± 0.0557b 1.43 ± 0.1153a

Crude fiber 0.34 ± 0.0721b 0.59 ± 0.1058a

Moisture 4.04 ± 0.0173a 3.94 ± 0.0200b

Carbohydrates 73.24 ± 0.7544a 72.57 ± 0.4444a

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a row are not significantly different (P > 0.05)

All values are expressed in dry weight basis of edible portions of anchote

Key: WB-whole wheat biscuit, AWB1- 10% fermented anchote-wheat biscuit, a, b, c, d, e …. are superscripts

given to show the significant difference between means, a > b > c > d….

� Mineral compositions

Mineral compositions of the control and 10% anchote-wheat biscuits were evaluated. All the

minerals under considerations were found to be increased significantly (P < 0.05) with

incorporations of anchote flour on wheat flour biscuits. The K contents were significantly

increased (P < 0.01) by 51% with 10% replacement of wheat flour with anchote flour. The

Ca contents were found to be 31.45mg/100g for control biscuit and 112.39mg/100g for

AWB1. Ca content was found to be significantly increased (P < 0.01) with 10% anchote flour

replacement. The percentage increase in Ca was 250%, which was an evident that anchote is

an ample source of Ca. Six-fold increase in Fe content was also observed, which was evident

that anchote flour has higher amount of Fe compared to wheat flour. A three-fold increment

in Zn content was also recorded.

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Table 4.8 Mineral compositions of anchote-wheat based biscuit

Minerals (mg/100g) K Ca Fe Zn

Control biscuit(WB) 153.27±0.6940b 31.45±0.6223b 0.61±0.09135b 0.42±0.0917b

AWB1 231.56±0.4603a 112.39±0.6471a 4.38±0.4543a 1.64±0.3651a

All values are the means of triplicates ± standard deviation.

Means with the same superscript letters within a column are not significantly different (P>0.05)

All values are expressed in dry weight basis of edible portions of anchote

Key: Ca-calcium, Fe-iron, Zn-zinc, K-potassium, a, b, c, d, e …. are superscripts given to show the significant

difference between means, a > b > c > d….

4.6 Sensory qualities of anchote-wheat biscuit

Color and flavor

Color is very important parameter in judging properly baked biscuits. It doesn’t only reflect

the suitable raw material used for the preparation but also provides information about the

formulation and quality of the product (Hussain, et al., 2006). As it can be seen from table

4.8 color has been observed to be significantly affected by blend proportion.

A decrease in the acceptability of the biscuit color was observed with an increase in the

amount of anchote in the blend. The color of the 10% anchote flour was found superior than

the rest of the blends scoring 7.12. This result was not significantly (P > 0.05) different from

the control biscuit signifying that replacement of wheat flour with anchote flour up to 10 %

didn’t bring a difference on the acceptability of the biscuits with respect to color.

Flavor is the main criterion that makes the product to be liked or disliked. Flavor, as color,

was observed to be affected significantly (P < 0.05) by blend proportion. The mean flavor

score of the biscuits was found to decrease with an increase in the proportion of anchote flour

in the biscuit. As with color, 10 % anchote flour biscuits were observed not to be

significantly (P < 0.05) different from the control biscuits with respect to flavor. Moreover,

means of flavor scores had exhibited similar scores and statistical interpretation to color.

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Crispiness

Crispiness was found to be affected significantly (P < 0.05) by blend proportion. Crispiness

was observed to decrease with an increase in the anchote flour proportion in the biscuits. As

with flavor and color, biscuits of 10% anchote flour were observed to not be significantly

different from the control biscuits. But the other two blends, 20 and 30% anchote flour were

found to be significantly different from the control and they were not acceptable.

Overall acceptability

Overall acceptability was affected significantly (P < 0.05) by blend proportion. A decrease in

the acceptability was observed with an increase in the amount of anchote flour in the

composite flour biscuits.

According to the analysis of the means, overall acceptability of 10% anchote flour biscuits

was not significantly different from the control. Moreover, the average mean score of overall

acceptability of 10% anchote flour biscuit was well above 7 (like moderately) suggesting that

it was well above minimum acceptable score. Therefore, as with all other sensory parameters,

supplementation of anchote flour up to 10% was observed to not have a significant difference

with wheat flour biscuits (control) with respect to overall acceptability. The other two blend

biscuits were observed to be significantly different from the control and their mean score was

observed to be below the minimum acceptable score (7, like moderately).

In general, the mean score of the overall acceptability of the biscuits ranged from 4.34 of the

30% anchote flour to 7.52 of the 10% anchote flour biscuits. These results very clearly

indicated that anchote flour can be used to replace a small portion of the wheat flour for

biscuit.

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Table 4.9 Sensory characteristics of anchote- wheat based biscuit

Sensory Qualities

Blend proportion

(WF : AF)

Color Flavor Crispiness Overall

acceptability

Control (100 : 00) 7.23±0.1436a 7.52±0.4264a 7.64±0.3486a 7.52±0.2638a

90 : 10 7.12±0.2311a 7.73±0.1991a 7.53±0.3752a 7.21±0.2463a

80 : 20 5.32±0.1149b 5.92±0.1278b 5.97±0.1963b 5.65±0.3186b

70 : 30 3.13±0.1875c 4.68±0.4376c 4.86±0.3486c 4.34±0.2179c

All values are the means of triplicates ± standard deviation

Means with the same superscript letters within a column are not significantly different (P > 0.05)

Key: WF-wheat flour, AF-fermented anchote flour, a, b, c, d, e …. are superscripts given to show the significant

difference between means, a > b > c > d….

a) AWB1 b) AWB2 c) AWB3

Fig 4.2 Biscuit made from anchote - wheat composite flour

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CHAPTER FIVE

SUGGESTED TECHNOLOGY FOR BISCUIT PRODUCTION

5.1 Biscuit-making procedure

Biscuits were prepared using fermented anchote flour, soft wheat flour and other ingredients

like sugar, shortening, ammonium bicarbonate and salt according to a commercial

formulation and baking practice of Kality Food Share Company. The dough was prepared by

blending fermented anchote flour and wheat flour with other ingredients and mixing it in

mixer (Model G.P.A. Orlandi mixer, Italy). The dough was removed from the mixer and

allowed to rest for 5 min. After that, the dough was sheeted using a sheeting machine

(Model: G.P.A. Orlandi sheeter, Italy) and flattened using roller into a sheet of about 1.5mm,

and then cut into circular pieces measuring 3.8cm in diameter. Samples were baked in an

electric convection oven (model G.P.A. Orlandi oven, Italy) at 1700C for 5 min, and were

allowed to cool for about 15 min on a rack. Then the biscuits are ready for packaging and

distribution.

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5.2 Material and energy balance

5.2.1 Material balance to prepare anchote flour

During washing, peeling and slicing of anchote root 6.4% is removed in the form of peels,

dusts, roots.

1000kg of Anchote Slices 936 kg

Peels, dusts, roots, water 64 kg

During the next unit operation, drying, the total loss in the form of water vapor accounts

50.1% of the initial weight.

Sliced mass 936 kg Dried anchote 435 kg

501 kg of moisture

The last stage was milling, at this stage there was 2.8% loss of the total weight. Finally the

anchote flour obtained from 1000 kg of anchote root was 407 kg which is 40.7% of the total

weight.

Dried Anchote Flour 435kg 407 kg of Anchote flour

Over sieve size 28kg

Milling and Sieving

Washing, Peeling and slicing

Drying

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5.2.2 Material balance for anchote-wheat biscuit preparation

� Assumptions for the production of biscuit

Ø The plant is working for 300 days per year and 16 hrs per day

Ø Dough moisture content is 25%

Ø Final biscuit moisture content = 3.94%

Ø Dry matter content of biscuit = 96.06%

Ø Production capacity of a machine is 5000kg /day so in order to calculate in an hourly basis,

divided its production capacity by 16 hrs

= = 312.5kg/hr

� Material balance during cooling and packaging of biscuit

Assummption: processing loss - 5%

Processing loss (0.05 × 312.5kg/hr =15.62kg/hr))

Biscuit leaving from oven (A) 312.5kg/hr

Moisture leaving from biscuit (B)

Moisture = 7% Moisture =3.94%

Dry matter content = 93 Dry matter content = 96.06%

General A = B + 15.62 kg/h + 312.5 kg/hr

A – B = 328.12kg/hr - - - - - - - - - - - - - - - - - - - - - - - - (1)

Moisture (A × 0.07) – B = 312.5kg/hr × 0.0394 + 15.62kg/hr × 0.0394

(A × 0.07) – B = 12.93kg/hr - - - - - - - - - - - - - - - - - - - - (2)

Substituting equation 1 into equation 2

(328.12kg/hr + B) × 0.07 – B = 12.93kg/h

Cooling and packaging

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0.93B = 10.04kg/hr

B = 10.8kg/h

B = 10.8kg/hr - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (3)

Substituting equation 3 in to equation 1

A = B + 15.62 + 312.5

A = 338.92kg/hr - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (4)

Dry matter

A × y = 312.5 × 0.9606 + 15.62 × 0.9606

A × y = 315.2

y = 93% - - - - - - - - - - - - - - - - -- - - -- - - -- - - - - - - - - - - (5)

� Material balance during baking (oven drying) of biscuit

Sheeted and laminated A (338.92kg/h)

Dough (C)

Moisture = 25% Water vapor (Wv) Moisture = 7%

Dry matter = x Dry matter content = 93%

General C = Wv + 338.92kg/hr - - - - - - - - - - - - - - - - - - - - - - - - - - - - (1)

Moisture C × 0 .25 = Wv + 338.92kg/hr × 0.07

C × 0.25 = Wv + 23.72kg/hr - - - - - - - - - - - - - - - - - - - - - - - - (2)

Dry matter C × x = 338.92kg/h × 0.93 - - - - - - - -- - - - - - - - - - - - - - - - - - (3)

Substituting equation 1 into equation 2

(Wv + 338.92kg/h) × 0.25 = Wv + 23.72kg/h

0.25 Wv + 84.73kg/h = Wv + 23.72kg/h

0.75 Wv = 61.01kg/h

Wv = 81.35 kg/hr - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - (4)

Substituting equation 4 into equation 1

C = Wv + 338.92kg/h

C = 81.35kg/hr + 338.92kg/h

Oven

Page 74

C = 420.27 kg/hr - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (5)

Substituting equation 5 into equation 3

C × x = 338.92kg/h × 0.93

420.27 × x = 338.92kg/h × 0.93

x = 75% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ( 6)

� Material balance during sheeting and laminating

Dough Mass (D) C (420.27 kg/h)

Moisture content = w Moisture = 25 %

Dry matter content = z Dry matter content = 75%

General D = 420.27 kg/hr

Moisture D × w= 418.78 × 0.25

w = 25%

Dry matter D × z = 418.78 × 0.75

z = 75%

� Material balance during mixing of ingredient

Flour and other recipe (M) D (420.27kg/h)

General M = 420.27kg/h

Sheeting & laminating

Mixing

Page 75

The amount of raw materials to make anchote-wheat biscuit are calculated in terms of

percentage of the total raw material required, and it is shown below.

Raw materials Percentage

ratio (%)

Amount required

to make 1000kg

dough

Amount required

in kg/h (Amount required

to make 420.27 kg dough

mix)

Wheat flour + Anchote flour 60.7 607 255.1

Fat(Shortening) 5.25 52.5 22.06

Sugar 13.35 191.7 56.11

Salt 0.41 4.1 1.72

Skimmed milk powder 0.3 3 1.26

Ammonium bicarbonate 0.79 7.9 3.32

Sodium bicarbonate 0.15 1.5 0.64

Sugar syrup 4.25 42.5 17.86

Water 14.71 147.1 61.82

Flavor 0.06 0.6 0.25

Color 0.03 0.3 0.13

Total 100.00 420.27

5.2.3 Energy balance during biscuit baking process

The major unit operation where heat and energy flow change in biscuit production is in the

oven. The oven uses electrical energy as a source of heat. This electrical energy is converted

to heat through the process of conduction, convection, and radiation in oven. The given

parameters to calculate the energy balance are given below:

Total mass of dough (M dough) = 420.27 kg/hr

Total mass of biscuit (M biscuit) = 338.92 kg/hr

M water vapor (Wv) = 81.35kg/hr

T dough = 250C

T biscuit = 1700C

Initial moisture of dough = 25%

Page 76

Temperature of dough after mixing (T ref) = 250c

Temperature of dough before entering to oven (T 1) = 300c

Assume Temperature of biscuit when it go out of oven (T2) =1700C

Final moisture content of biscuit = 7%

Latent heat of evaporation for water at 1000c (λ) = 2257kJ/kg

Composition of dough (M = 25, P = 8.11, F = 6.72, CHO = 59.23, and A = 0.94)

Composition of biscuit (M = 3.94, P = 9.1, F = 12.37, CHO=72.57, and A=1.43)

C p dough = 1.424Xc + 1.549Xp+1.675Xf + 0.837Xa+4.187Xw (kJ/kg.k)

C p dough = 1.424(0.5923) + 1.549(0.0811) + 1.675(0.0672) + 0.837(0.0094) + 4.187(0.25)

C p dough = 2.14kJ/ kg.k

C p biscuit = 1.424Xc+ 1.549Xp+ 1.675Xf + 0.837Xa + 4.187Xw (J/kg.k)

C p biscuit = 1.424(0.7257) + 1.549(0.091) + 1.675(0.1237) + 0.837(0.0143) + 4.187(0.0394)

C p biscuit = 1.56 J/ Kgk

Q water vapor

Q feed Q product

Q electrical heating

General

Q feed + Q electric heating = Q water vapor + Q product - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - (1)

Q feed = M dough CP dough (T feed-T ref)

= 420.27 kg/hr x 2.14kJ/ kg.k × (30-25) k

= 2.48 × 106J/hr - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - (2)

Q product = M product C p product(T2 – T1)

= 338.92 kg/hr × 1.56 kJ/ kg.k (170-30) k

Oven

Page 77

= 7.40 × 10 7J/hr - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (3)

Q water vapour = M water vopour × λ water vapour ( at 1000C)

= 81.35kg/hr × 2257kJ/kg

= 1.836 × 108 J/hr - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (4)

Substituting equation 2, 3, & 4 into equation 1

Q feed + Q electric heating = Q water vapour + Q product

Q electric heating = Q water vapour + Q product – Q feed

= 1.836 × 108J/hr + 7.40 × 10 7J/hr – 2.48 × 106J/hr

= 2.6 × 108 J/hr - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (5)

5.3 Economic analysis of the study

Given Plant parameters

• Capacity, tons per year 1500 ton per year

• Number of shifts /day 2

• Working days/year 300

• Land area/ covered, m2 1500

� Machinery and equipment cost

If the cost of a piece of equipment or plant of size or capacity q1 is C1, then the cost of a

similar piece of equipment or plant of size or capacity q2 can be calculated from C2=C1

(q2/q1 )n 2 (Robert H. Perry, 2007). Where the value of the exponent n depends on the type

of equipment or plant (Appendix II).

Page 78

Table 5.1 Major equipments delivered purchasing cost

SN Item Quantity Unit Price(birr) Total Price(birr)

1 Universal Mixer

420.27kg/h capacity

1 79,589.00 79,589.00

2 Flour sifter 1 58,566.00 58,566.00

3 laminator 1 52,000.00 52,000.00

4 Rotary cutting

machine

1 33,000.00 33,000.00

5 Electric band oven -

size 25m

1 187,198.00 187,198.00

6 Cooling conveyer -

size 10m

1 13,200.00 13,200.00

7 Work conveyer – size

10m

1 19,566.00 19,566.00

8 Heat sealer 2 32,567.00 65,134.00

9 Delivery vehicle 1 500,000.00 500,000.00

10 Water tank(6000L) 1 8,456.00 8,456.00

11 Water tank(10,000L) 1 10,000.00 10,000.00

12 Water tank(15,000L) 1 13,489.00 13,489.00

13 Weighing scale 1 31,234.00 31,234.00

14 Contingencies on equipment (15 %)

136,630.00 141,215.00

Total 13 1,047,495.00 1,232,146.80

Page 79

� Manpower requirement

Table 5.2 Human resource requirement

Work specification Required

number

Gross monthly

salary(birr)

Total monthly

salary(birr)

Yearly

salary(birr)

Manager 1 6,000 6,000 72,000

Production head 1 3,000 3,000 36,000

Quality Head 1 3,000 3,000 36,000

Purchasing and sales

head

1 3,000 3,000 36,000

Secretary 1 1,300 1,300 15,600

Laboratory technician 2 1,500 3,000 36,000

Mechanical engineer 1 3,000 3,000 36,000

Production shift leader 2 2,500 5,000 60,000

Mechanics 2 900 1,800 21,600

File directory 1 900 900 10,800

Production line workers 9 900 8,100 97,200

Raw material storage

area workers

8 900 7,200 86,400

Final product storage

area workers

8 900 7,200 86,400

Security guard 6 1,100 6,600 79,200.00

Cleaners 6 1,000 6,000 72,000.00

Total 50 29,950 65,100 781,200.00

� Cost of raw materials

The cost of each raw material per annum is calculated by multiplying the raw material

required per hour by 300 working days per year and 16hour per day and then multiply by

their unit price. The unit price for water is 0.0035 Birr/liter.

Page 80

Table 5.3 Cost of raw materials

Particulars Quantity

per hour

(kg/h)

Quantity

per day

(kg/day)

Quantity per

annum

(kg/year)

Unit price

(birr/kg)

Total cost

(birr/kg)

Wheat flour 229.6

3673.6 1,102,080

11 12,122,880.0

0

Anchote

flour

25.5 408 122,400

11 1,468,800.00

Shortening 22.06 352.96 105,888 25.00 1,270,656.00

Sugar 56.11 897.76 269,328 14.50 3,231,936.00

Salt 1.72 27.52 8,256 3.00 99,072.00

Flavor 0.25 4 1,200 18.00 14,400.00

Sodium

bicarbonate

0.64 10.24 3,072

12.00 36,864.00

Ammonium

bicarbonate

0.79 12.64 3,792

12.00 45,504.00

Skimmed

Milk

Powder

1.26

20.16 6,048

50

72,576.00

Water 61.82 989.12 296,736 0.0035 1,039.00

Total

399.75 6396 1,918,800

18,363,727.0

0

� Cost of utility

The water required for the production of biscuit includes the water required for the main

production line, for laboratory, for cleaning and others like for garage and for steam on

process line. The yearly water consumption of Kality food Share Company is 510,000 litters

and half of this is taken for this anchote-wheat biscuit production plant. The packaging

material for the biscuit has a capacity of 250gm per pack. The yearly production of 1,500,000

(312.5 × 16 × 300) kilogram per year and it requires 6,000,000 packs per year.

Page 81

Table 5.4 Cost of utilities

Utilities Quantity per

annum

Unit price (Birr) Total cost (Birr)

Electricity (Kwh) 346,666.7 0.51 176,800.00

Water (L) 255,000 0.0035 892.00

Packing material

(packs)

6,000,000 0.7 4,200,000.00

Total 4,377,692.00

� Fixed capital cost estimation

The factors are based on the grass type processing industries and based on the data of H. C.

Bauman, Fundamentals of Cost Engineering in the Chemical Industry, Van Nostr and

Reinhold, New York, 1964, p. 295, for essentially carbon steel equipment. For, a given

company’s labor costs and material costs may inflate at different rates. To quite a large

extent, inflation becomes repressed, or differentiated, in such fields as taxation, import

control, and price restriction. The material and labor cost is estimated 5.27 times the sum of

equipment, installation, instrumentation, piping, and electrical cost. See appendix-III.

Page 82

Table 5.5 Estimation of direct and indirect cost

Item Description/factor Total cost, birr

Direct cost A. Material + labor Estimated 19,144,927.00

a. Equipment Estimated 1,928,311

b. Installation 0.09 × TEC 110,893.00

c. Instrumentation 0.13 × TEC 160,179.00

d. Piping 0.29 × TEC 221,786.00

e. Electrical 0.18 × TEC 194,876.00

B. Building 0.24 × TEC 295,715.00

C. Service facilities 0.4 × TEC 492,858.00

D. Land 0.06 × TEC 73,928.00

Total direct cost A + B + C + D 22,623,473.00

Indirect cost A. Engineering

&supervision

0.1 × TDC 2,262,347.00

B. Construction +

Contractor fee

0.1 × TDC 2,262,347.00

C. Contingency 0.06 × TDC 1,357,408.00

Total indirect cost A + B + C 5,882,102.00

ІІІ. Fixed capital investment Direct + Indirect cost 28,505,575.00

ІV. Working capital 0.15 × FCI 4,275,836.00

V. Total capital investment ІІІ + ІV 32,781,411.25

Page 83

Table 5.6 Estimation of total product cost

Item Description/factor Total cost, birr

І. Manufacturing cost

A. Fixed Charges

a. Depreciation 0.1×instrumentation + 0.02×building 21,932.00 b. Local taxes 0.02×FCI 570,111.00 c. Insurance 0.006×FCI 171,033.00 Total of A 763,076.00 B.Direct production cost

Total production cost (tpc)

Total fixed charge/0.15 5,087,173.00

a. Raw material Already estimated 18,363,727.00 b. Utilities 4,377,692.00 c. Operating labor (ol)

0.1×tpc 508,717.00

d. Supervisory 0.1×ol 50,871.00 e. Maintenance 0.05*FCI 1,425,278.00 f. Lab charges 0.12×ol 61,046.00 Total of B 29,874,504.00 C. Plant overheads

0.1×tpc 508,717.00

Total manufacturing cost

A + B + C 31,146,297.00

П. General Expenses a. Administrative cost

0.05×tpc 254,358.00

b. Distribution 0.1×tpc 508,717.00

c. R & D 0.05×tpc 254,358.00

d. Interest 0.05×tpc 254,358.00

Total general expenses

1,271,791.00

Total product cost І + П 32,418,088.00

Total product cost/kg of biscuit per year 21.61

Page 84

� Gross earnings

BEP = Break-even point (units of production)

ROR = Rate of return

Vcup = Variable costs per unit of production

Sup = Selling price per unit of production

TPC = Total product cost

DPC = Direct production cost

NP = Net profit

FCI = Fixed capital investment

Assuming that whole selling price of 1kg of biscuit =26birr

Expecting all produced biscuit will be sold

Total income = 26×1,500,000 = 39,000,000.00

Gross income = total income – total product cost …………………………………….. (5.1)

= 39,000,000.00 – 32,418,088.00 = 6,581,912.00 birr

Let the tax rate be 35% (income tax of Ethiopia)

Vat is 10% of gross income

The taxable is 30% of yearly income (gross income)

Taxable money = 30% × 6,581,912.00 birr = 1,974,573.6 birr

Taxes = 0.35×1,974,573.6 birr = 691,100.76 birr

Vat= 10%×6,581,912.00 = 658,191.2birr

Net profit = gross income – (tax + vat) ………………………………………………… (5.2)

= 6,581,912.00 – (691,100.76 + 658,191.2) birr

= 5,232,620.04 birr/year

Rate of return

ROR = × 100 = × 100 = 16% … (5.3)

Payback period = = = 5years …………….... (5.4)

Page 85

Breakeven point

V cup = = = 19.91birr/kg …………………. (5.5)

BEP = = = 417,665.7 kg/year ……. (5.6)

BEP (%) = = × 100 = 27.84% …………….. (5.7)

� Plant location

To select proper locations and sites, certain key requirements or criteria should be set, that

would allow the assessment of a number of potential locations, and the rejection of those not

fulfilling those requirements. It is assumed that the factory or plant is installed in the western

Ethiopia region where the production of Anchote is high and there is availability of utilities

such as water, electricity and other infrastructures in Nekemte area.

Page 86

5.4 Equipment layout of biscuit producing plant

Figure 5.1 Equipment layout of biscuit producing plant

Page 87

CHAPTER SIX

CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions

The study attempted to investigate the effect of three processing methods (boiling, roasting

and natural fermentation) on nutritional composition, antinutritional factors, functional and

physicochemical properties of anchote flour and the possibility of using anchote flour for the

production of biscuit by blending with wheat flour.

From the results of the present study it was understood that anchote contains appreciable

quantity of carbohydrate, crude protein, crude fiber, calcium, potassium and iron. The results

of this study also showed that anchote contains low levels of antinutrients (phytate, tannin,

oxalate and cyanide) when compared to other root and tuber crops. Moreover, there were

further reductions of the antinutritional factors during processing. Additionally, it was

observed in the study that functional property of anchote flour is remarkably higher. Higher

water absorption capacity, oil absorption capacity, swelling power and solubility index than

other root crops flour was recorded. But the foaming capacity and stability was lower.

Evaluation of the three processing methods in terms of antinutrients reduction and nutrients

enrichments indicated that all the three processing method was found to be effective in the

reduction of antinutrients. Effect of natural fermentation was found to be highest in the

reduction. In relation to nutritional profile, the low protein content of both anchote flour

samples was observed to be increased by fermentation. Natural fermentation of anchote flour

is a more acceptable process as it is inexpensive, fuel efficient method and environmentally

friendly by which people can obtain good quality food and this process can only be

performed at their own homes. However, boiling and roasting were found to enhance most of

the functional properties of anchote flour. Fermentation enhances the foaming capacity of the

raw anchote flour.

Page 88

The results found also indicated that anchote flour could be blended with wheat flour to

produce biscuit with acceptable sensory qualities. It was found that the more the anchote

flour in the composite, the more the fiber and ash content of the biscuits. Incorporation of the

anchote flour up to 10% resulted in biscuit of comparable in sensory qualities with respect to

biscuits produced using 100% wheat flour (control biscuit). In regard to nutritional profile the

mineral content and crude fiber content of the control biscuit were improved substantially.

As per the results of this study, anchote-wheat flour biscuit are both nutritious and exhibited

acceptable sensory quality. Thus it could be concluded that the composite flour will reduce

our dependence in the wheat flour for the production of biscuit and other similar products.

The results of this study are good indicators of the possibility for better utilization of anchote

through developing variety of new food products.

6.2 Recommendations

Due to the low attention given to the research and development of anchote, there is no variety

so far developed and released. As anchote is an endemic and potential root crop, further

research should be done for the development and release of anchote variety. Cultivation of

anchote should be introduced to anchote non-growing areas of the country, as it is rich

sources of protein, carbohydrate, calcium, iron and potassium; it can play its role in ensuring

food security.

The following recommendations are made based on the experiences faced during the study

� In order to prevent the possible nutritional impacts on consumers of anchote from

other antinutritional factors, such as trypsin inhibitors, amylase inhibitors and others,

the crop should be investigated for these antinutritional factors.

� Analysis should be done for the vitamins and other minerals content of anchote

� Anchote is an excellent source of carbohydrate. Therefore it can be used as industrial

raw material for starch production. Determining the quality and quantity of starch

found in anchote could be one area which needs investigation.

Page 89

� Biscuit production from anchote-wheat composite flour should be given due emphasis

and processors should be encouraged to utilize the potential of anchote flour thereby

diversify their products for better income and service for the consumer.

� A comprehensive study on optimization of ingredient and baking condition and shelf

life stability of baked products of anchote blended with other cereals should be

conducted to come-up with complete and usable information.

� Studies should be done on other value added anchote based food products like

anchote supplemented cookies, breads and others and as it has medicinal importance

using the anchote flour for new functional and neutraceutical food products should

also be assessed.

Page 90

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APPENDICES

Appendix-I Photo of anchote processing and laboratory equipments used

a) Nekemte anchote tuber b) Dembidollo anchote tuber

c) Sliced anchote tuber d) Drying anchote in oven e) Dried anchote samples

f) Anchote flour (dembidollo sample) g) Anchote flour (Nekemte sample)

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h) AWB1 i) AWB2 j) AWB3

k) Mixer B15 l) MB 35 moisture analyzer

m) Screen n) miller

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Appendix-II The value of cost index (n) for different equipments

(Source: Robert H. Perry, 2007)

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Appendix-III Factors with separation of materials and labor

(Source: H. C. Bauman, 1964)