THESIS EFFECT OF DIFFERENT RICE BRAN CONCENTRATIONS AND BAKING TIME ON THE CONSUMER PREFERENCES AND PHYSICO-CHEMICAL CHARACTERISTICS OF GLUTEN FREE – RICE BRAN BROWNIES Written as partial fulfillment of the academic requirements to obtain the degree of Sarjana Teknologi Pertanian Strata Satu By : NAME : MERRYO SETYAWAN NPM : 03420080102
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THESIS
EFFECT OF DIFFERENT RICE BRAN CONCENTRATIONS
AND BAKING TIME ON THE CONSUMER PREFERENCES
AND PHYSICO-CHEMICAL CHARACTERISTICS OF
GLUTEN FREE – RICE BRAN BROWNIES
Written as partial fulfillment of the academic requirementsto obtain the degree of Sarjana Teknologi Pertanian Strata Satu
By :NAME : MERRYO SETYAWAN NPM : 03420080102
FOOD TECHNOLOGY DEPARTMENTFACULTY OF INDUSTRIAL TECHNOLOGY
UNIVERSITAS PELITA HARAPANKARAWACI
2012
STATEMENT OF THESIS AUTHENTICITY
I, a student of Food Technology Department, Faculty of Industrial Technology, Universitas Pelita Harapan,
Name : Merryo SetyawanStudent Id. Number : 03420080102Department : Food Technology
Hereby declare that my thesis, entitled “EFFECT OF DIFFERENT
RICE BRAN CONCENTRATIONS AND BAKING TIME ON THE
CONSUMER PREFERENCES AND PHYSICO-CHEMICAL
CHARACTERISTICS OF GLUTEN FREE – RICE BRAN BROWNIES” is:
1) An original piece of work, written and completed on my own, based on
lecture notes, data observation, reference books, journals, and other
sources as listed on the work cited section.
2) Not a duplication of other writing that has been published or used for
obtaining the degree of Sarjana in other Universities, except for passages
that include information on respective references.
3) Not a translation of other works from books or journals, which are listed
on the work cited section.
I understand that if my statement above is proven untrue, this Thesis will be
canceled.
Karawaci, June 15th, 2012
(Merryo Setyawan)
Materai Rp
UNIVERSITAS PELITA HARAPANFACULTY OF INDUSTRIAL TECHNOLOGY
APPROVAL BY THESIS SUPERVISORS
EFFECT OF DIFFERENT RICE BRAN CONCENTRATIONS AND BAKING TIME ON THE CONSUMER PREFERENCES AND PHYSICO-
CHEMICAL CHARACTERISTICS OF GLUTEN FREE – RICE BRAN BROWNIES
Written By :Name : Merryo SetyawanStudent Id. Number : 03420080102Department : Food Technology
has been approved to be examined for obtaining the degree of Sarjana Teknologi Pertanian Strata Satu in the Food Technology Department, Faculty of Industrial Technology, Universitas Pelita Harapan Karawaci – Tangerang, Banten.
Karawaci, June 15th, 2012
Approved by:
Supervisor Co-Supervisor
(Dr. Ir. Raffi Paramawati, M.Si) (Natania, M. Eng )
Acknowledged by,
Head of Food Technology Department
(Nuri Arum Anugrahati, MP)
UNIVERSITAS PELITA HARAPAN FACULTY OF INDUSTRIAL TECHNOLOGY
APPROVAL BY THESIS EXAMINATION COMMITTEE
We the undersigned, certify that a thesis defense has been held on February 10th, 2012, as partial fulfillment of the academic requirement to obtain the degree of Sarjana Teknologi Pertanian Strata Satu in the Food Technology Department, Faculty of Industrial Technology, Universitas Pelita Harapan, for the student:
Name : Merryo Setyawan
Student Id. Number : 03420080102
Department : Food Technology
Faculty : Industrial Technology
With the following title “EFFECT OF DIFFERENT RICE BRAN
CONCENTRATIONS AND BAKING TIME ON THE CONSUMER
PREFERENCES AND PHYSICO-CHEMICAL CHARACTERISTICS OF
GLUTEN FREE – RICE BRAN BROWNIES”, and that the thesis has been approved by the examination committee.
Examiners Signature1. Head of Examiners2. Member 3. Member
ABSTRACT
Merryo Setyawan (03420080102)
EFFECT OF DIFFERENT RICE BRAN CONCENTRATIONS AND BAKING TIME ON THE CONSUMER PREFERENCES AND PHYSICO-CHEMICAL CHARACTERISTICS OF GLUTEN FREE – RICE BRAN BROWNIES
Rice bran is by product of rice milling categorized as a food source which contains good source of dietary fiber and other nutritions components. However, the utilization of rice bran in Indonesia is very limited, on the other hand, Indonesian people lack of dietary fiber consumption in their daily diets. Food product which is made from wheat flour contains gluten that is restricted in the diet of patient with celiac disease. Hence, replacing the use of wheat flour in the production of brownies with gluten free food sources such as cassava flour, rice flour and potato flour with rice bran substitution is expected to overcome the problem above. The general objective of this research is to study the utilization of rice bran in the making of gluten free rice bran brownies. The preliminary research was conducted with by incorporating different types of flour (cassava flour, rice flour, potato flour). From the preliminary research the rice bran brownies made from cassava flour was not significant different with rice bran brownies made from wheat flour in term of overall acceptance. The main research was conducted with two factors, which is rice bran concentration (0,10,20,30 and 40%), and baking time (35,45, and 55 minutes). The analysis that was done was the sensory analysis and phsyico – chemical analysis regarding hardness, moisture content and water activity. From the main research, the rice bran brownies which obtained the highest value of overall acceptance was the rice bran brownies made using 30% rice bran and 55 minutes baking time. Therefore, it was selected as the best formulation. The dietary fiber content of the best rice bran brownies formulation was 7.99%, and it was categorized as high fiber food because it fulfilled more than 20% RDA of dietary fiber.
Table 3.2 Formula Modification.......................................................................21
Table 3.3 Combination of Factors....................................................................25
Table 4.1 Interaction of Rice Bran Concentration and Baking Time towards Aroma Parameter .............................................................................................48
Table 4.2 Interaction of Rice Bran Concentration and Baking Time towards Texture Parameter ............................................................................................54
Table 4.3 Interaction of Rice Bran Concentration and Baking Time towards Texture Parameter ............................................................................................57
Table 4.4 Proximate Composition of Rice Bran Flour.....................................66
Table 4.5 Proximate Composition of The Best Formulation............................67
vii
LIST OF FIGURES
Figures 3.1 Flowchart of main research.........................................................22
Figure 4.1 Preference of Aroma by Panelists.................................................30
Figure 4.2 Preference of Taste by Panelists...................................................32
Figure 4.3 Preference of Texture by Panelists...............................................34
Figure 4.4 Preference of Overall Acceptance by Panelists............................36
Figure 4.5 Hardness Parameter of Rice Bran Brownies.................................37
Figure 4.6 Moisture Content of Rice Bran Brownies ....................................39
Figure 4.7 Water Activity of Rice Bran Brownies.........................................41
Figure 4.8 Effect of Rice Bran Concentration Towards Aroma Parameter. . .45
Figure 4.9 Effect of Baking Time Towards Aroma Parameter......................46
Figure 4.10 Effect of Rice Bran Concentrations Towards Taste Parameter. .49
Figure 4.11 Effect of Baking Time Towards Taste Parameter.......................50
Figure 4.12 Effect of Rice Bran Concentration Towards Texture Parameter
2. Baking time (B), which consists of three levels :
- 35 minutes baking time (B1)
- 45 minutes baking time (B2)
- 55 minutes baking time (B3)
Based on the treatment, the experimental design used in this research is complete
random design with two factorials, R x B (5x3). The main research was conducted
in three replications. Factor which observed were :
1. The concentration of rice bran which was added to the formulation, which
consist of R0, R1, R2, R3 and R4.
2. The different baking time, which were B1, B2 and B3.
The combination of the factors can be seen in Table 3.3.
Table 3.3 Combination of FactorsBaking Time Rice Bran Concentration
24
R0 R1 R2 R3 R4B1 R0B11
R0B12
R0B13
R1B11
R1B12
R1B13
R2B11
R2B12
R2B13
R3B11
R3B12
R3B13
R4B11
R4B12
R4B13
B2 R0B21
R0B22
R0B23
R1B21
R1B22
R1B23
R3B21
R3B22
R3B23
R3B21
R3B22
R3B23
R4B21
R4B22
R4B23
B3 R0B31
R0B32
R0B33
R1B31
R1B32
R1B33
R2B31
R2B32
R2B33
R3B31
R3B32
R3B33
R4B31
R4B32
R4B33
The randomized factorial design is :
Yijk = µ + Ri + Sj + Rsij + Ɛ1 (ijk)
Where :
Yijk = value of observation at level one, with factor of concentration of rice bran
flour on level i and different type of sugar on level j
µ = real mean value
Ri = effect of concentration of rice bran flour on level i
Sj = effect of different type of sugar used on level j
Rsij = effect of interaction between factor of concentration of rice bran flour on
level i and factor of different type of sugar used on level j
Ɛ1 (ijk) = Galat factor
Hipotesis of this research :
Ho :
25
1. There is no effect on concentration of rice bran flour towards the quality
and sensory acceptance of gluten free – high dietary fiber brownies
2. There is no effect on concentration of different types of sugar used
towards the quality and sensory acceptance of gluten free – high dietary
fiber brownies
3. There is no interaction on concentration of rice bran flour and different
types of sugar used towards the quality and sensory acceptance of gluten
free – high dietary fiber brownies
H1 :
1. There is effect on concentration of rice bran flour towards the quality and
sensory acceptance of gluten free – high dietary fiber brownies
2. There is effect on concentration of different types of sugar used towards
the quality and sensory acceptance of gluten free – high dietary fiber
brownies
3. There is interaction on concentration of rice bran flour and different types
of sugar used towards the quality and sensory acceptance of gluten free –
high dietary fiber brownies
3.4 Analysis Procedure
The parameters which were observed in this research were the sensory qualities,
physical, and chemical characteristic of the gluten free rice bran brownies. The
proximate analysis and the dietary fiber analysis was done for the best gluten free
rice bran brownies formulation.
3.4.1 Sensory Qualities26
The sensory qualities of the gluten free rice bran brownies was determined by
using sensory evaluation test which was the hedonic test (Meilgaard, 2007). The
hedonic test was conducted to determine the gluten free rice bran brownies
formula which was most preferred by the panelist. The panelist in this sensory
evaluation procedure was untrained panelist. The method for the hedonic test
could be seen in Appendix 1.
3.4.2 Physical Characteristic
The physical characteristic of the gluten free rice bran brownies was determined
by using texture analyzer towards the hardness parameter. The method of
determining the texture of the gluten free high rice bran brownies could be seen in
Appendix 2.
3.4.3 Chemical Characteristic
The chemical characteristic of the gluten free rice bran brownies which was
evaluated consists of moisture content and water activity. The water activity was
measured using Aw meter while the method of determining moisture content could
be seen in appendix 3.
3.4.4 Proximate Analyses for the best gluten free - high dietary fiber
brownies formulation
The proximate analyses of the gluten free rice bran brownies included the oven
method to determine the moisture content of the rice bran (AOAC, 2005), ash
content using the dry ashing method (AOAC, 2005), protein content using the
27
micro Kjehdahl method (AOAC, 2005),fat content using the soxhlet extraction
(AOAC, 2005) and carbohydrate content using by difference method. The
proximate analyses methods could be seen in Appendix 3. The dietary fiber
content of the gluten free - high dietary fiber brownies was also analyzed by using
enzyme analysis (AOAC,2005). The method for dietary fiber analysis could be
seen in the Appendix 4.
CHAPTER IV
RESULTS AND DISCUSSIONS
4.1 Result of Preliminary Research
28
The preliminary research was conducted to determine the best gluten
free flour that would be used as the wheat flour replacer in the making of rice bran
brownies. There were four types of flour which were used in the preliminary
research which were cassava flour, rice flour, potato flour and wheat flour. The
subjective and objective test were conducted to analyze the rice bran brownies
which were made using different types of flour. The subjective test that was
conducted was sensory evaluation using hedonic test. The hedonic test was
conducted in order to determine the best wheat flour replacer. There were four
quality parameters of the hedonic test which was observed, which was aroma,
taste, texture and overall acceptance of the rice bran brownies. The objective
analysis was conducted to observe several physical and chemical parameters
which consist of moisture content, water activity and the texture of rice bran
brownies.
4.1.1 Sensory Analysis
The determination of the best gluten free flour was conducted based
on sensory evaluation procedure. The hedonic test was conducted as the sensory
evaluation procedure. According to Moskowitzt et al (2006), The number of
panelists required for conducting the consumer sensory acceptance tests was 50 –
100 panelists, therefore in this research, the hedonic test were conducted using 70
panelists. The panelists were untrained panelists and the panelists were asked to
evaluate each of the rice bran brownies samples using a 7 points hedonic scale.
The scale was ranged from 1 to 7, 1 stands for extremely dislike and 7 stands for
extremely like. The evaluation of each samples were done based on the preference
29
of the panelists toward each samples. All of data obtained from the hedonic test
were analyzed using the IBM SPSS 19 utilizing the one way ANOVA.
4.1.1.1 Aroma
Aroma was chosen as one of the parameter in the hedonic test to
observe the consumer preference towards the different types of flour used to make
the rice bran brownies.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely like
Figure 4.1 Preference of Aroma by PanelistsThe result of the hedonic test towards the aroma parameter can be
seen in the Figure 4.1. From the statistical analysis using one way ANOVA, from
the ANOVA table, it could be seen that there was a significant different between
the types of flour used toward the consumer acceptance of rice bran brownies
aroma. The most preferable rice bran brownies based on aroma parameter was the
30
Types of Flour4.2
4.4
4.6
4.8
5
5.2
5.4
5.0857a
5.2a
4.7571ab
4.5857b
Wheat FlourCassava FlourRice FlourPotato Flour
rice bran brownies made from cassava flour as shown in the Figure 4.1. Although
the rice bran brownies made from cassava flour has the highest score in terms of
aroma parameter, from the statistical analysis done using one way ANOVA, it
was not significantly different with the consumer acceptance of aroma parameter
toward the rice bran brownies made from rice flour and wheat flour. There was a
research conducted by Katama et al (2002) about the substitution of wheat flour
with cassava flour in chapatti, in that research, substitution 50 % of wheat flour
with cassava flour still produced chapatti with acceptable aroma. The result of that
research was coherent with the result of this research. It could be concluded that
the replacement of wheat flour with cassava flour still could produce baked
product, in this case was rice bran brownies, which was still acceptable to
consumers, in terms of aroma parameter. The aroma of rice bran brownies
produced from rice flour was also still acceptable for consumers.
The rice bran brownies made from potato flour gave the lowest score
of the consumer acceptance toward aroma parameter, it was not significantly
different with the rice bran brownies made from rice flour, but it was significant
different with the rice bran brownies made from cassava flour and wheat flour.
Basically the aroma of the rice bran brownies was produced from the rice bran
and the cocoa powder which were used in the formulation. A research was
conducted by Thybo et al (2006) regarding several aromatic compounds which
were found in potatoes from several different cultivars. According to Berger
(2007) approximately 50 compounds contributed to the aroma of raw potato.
Because of the existence of such aromatic compounds, it could be inferred that
potato flour would have a distinctive aroma. These aroma compounds could give
31
changes towards the aroma properties of the rice bran brownies and affect the
consumer preference towards the rice bran brownies aroma.
4.1.1.2 Taste
Taste was chosen as one of the parameter in the hedonic test to
observe the consumer preference towards the different types of flour used to make
the rice bran brownies.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely like
Figure 4.2 Preference of Taste by Panelists
The result of the hedonic test towards the taste parameter can be seen
in the Figure 4.2. From the result of statistical analysis by one way ANOVA, from
the ANOVA table, it could be seen that there was a significant different between
the types of flour used toward the consumer acceptance of rice bran brownies
taste. As shown in Figure 4.2, the rice bran brownies which gave the highest score
32
Types of Flour0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
4.4a4.2143a 4.1a
3.5857b
Wheat FlourCassava FlourRice FlourPotato Flour
towards the taste parameter was the rice bran brownies made from wheat flour,
but from the statistical analysis, there was no significant difference between wheat
flour, cassava flour and rice flour toward the sensory acceptance of rice bran
brownies regarding taste parameter. There was a research conducted by Gan et al
(2007) about the optimization of cassava cake formulation which produce cassava
cake with high consumer acceptance, the research was stated that the baked
cassava cake had a strong cassava flavour. The cassava flavour produced from the
cassava flour during baking could possibly affect the consumer acceptance toward
the taste parameter, although the cassava flavour itself had not beed studied
extensively yet. According to Dziedzoave (2006), high quality cassava flour
should have bland taste without indication of acidity or off flavour, and also
should have the flavour of freshly peeled cassava.
The rice bran brownies made from potato flour was slightly
unacceptable because as shown in the Figure 4.2 the mean score for taste
parameter was 3.5857, while based on the hedonic scaling range, the score 3
already categorized as “slightly dislike”. The low acceptance towards the taste of
rice bran brownies made from potato flour could be affected by the potato flavour
produced from the potato flour. Thybo et al (2006) stated that the potato flavour is
correlated with the aromatic compounds contained in the potato, furthermore, it
also stated that potato could possible have an off flavour which was correlated
with the non volatiles compounds in the potato.
4.1.1.3 Texture
33
Texture was chosen as one of the parameter in the hedonic test to observe the
consumer preference towards the different types of flour used to make the rice
bran brownies.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.3 Preference of Texture by Panelists
The result of the hedonic test towards the taste parameter can be seen
in the Figure 4.3. From the result of statistical analysis by one way ANOVA, from
the ANOVA table, it could be seen that there was a significant different between
the types of flour used toward the consumer acceptance of rice bran brownies
texture. As shown in Figure 4.3, the rice bran brownies which gave the highest
score towards the texture parameter was the rice bran brownies made from wheat
flour, but it was not significantly different with rice bran brownies made from
cassava flour. From the Figure 4.3 it could be seen that the mean score given by
the panelist is slightly lower for the rice bran brownies produced from cassava
flour. There was a research conducted by Gan et al (2007) about the optimization 34
of cassava cake formulation, in that research the texture parameter of the product
which was firmness was not quite acceptable by the panelists. It could be assumed
that the cassava flour could affect the texture of the baked product which would
affect the consumer preference of the baked product in terms of texture.
The lowest acceptance in term of texture was given by the rice bran
brownies produced from potato flour. From the result in could be concluded that
potato flour utilization in the making of rice bran brownies might cause a textural
change towards the product which could reduce the textural acceptability of the
rice bran brownies from the consumer.
4.1.1.4 Overall Acceptance
The overall acceptance parameter was chosen as one of the parameter
to be evaluated in the hedonic test as its importance to determine the preference of
the consumer towards the rice bran brownies product in terms of combined
evaluation regarding the aroma, taste and texture of the rice bran brownies.
35
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.4 Preference of Overall Acceptance by Panelists
The result of the hedonic test towards the overall parameter can be
seen in the Figure 4.4. From the result of statistical analysis by one way ANOVA,
from the ANOVA table, it could be seen that there was a significant different
between the types of flour used toward the consumer acceptance of rice bran
brownies regarding the overall acceptance. As shown in Figure 4.4, the rice bran
brownies which gave the highest score towards the overall acceptance parameter
was the rice bran brownies made from wheat flour, but it was not significantly
different with rice bran brownies made from cassava flour.
From Figure 4.4, the flour which gave the lowest overall acceptance
towards the rice bran brownies was the potato flour, although it was not
significantly different with rice bran brownies made from rice flour. Based on the
sensory evaluation result utilizing hedonic test, the best gluten free flour which
could be used in the making of rice bran brownies was the cassava flour, because
36
Types of Flour0
1
2
3
4
5
6
5.1286a4.9143a
4.2143b3.9429b
Wheat FlourCassava FlourRice FlourPotato Flour
it still gave product which was acceptable by the consumer and was not
significantly different with rice bran brownies made from wheat flour.
4.1.2 Physical and Chemical Analysis
4.1.2.1 Texture
The texture of rice bran brownies made from different types of flour
was analyzed using texture analyzer. The textural parameter which was observed
was hardness parameter. As stated by Sczcneiak (2002), hardness could be
defined physically as force give to attain a given deformation and from sensory
perspective hardness was defined as force require to compress between molar
teeth and palate. The hardness parameter of rice bran brownies made with
different types of flour could be seen in the Figure 4.5.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.5 Hardness Parameter of Rice Bran Brownies
37
Types of Flour0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
5676.04a6158.58a
4156.073b
8982.1587c
Wheat FlourCassava FlourRice FlourPotato Flour
The hardness parameter from rice bran brownies made from different
types of flour was statistically analyzed using one way ANOVA, and from the
ANOVA table it was resulted that there was a significant difference between rice
bran brownies made from different types of flour towards the hardness parameter.
From Figure 4.5 it could be seen that the highest level of hardness was given by
rice bran brownies made using potato flour, and the lowest one was the rice bran
brownies made using rice flour. This result could be correlated with the result
obtained from sensory analysis, in the sensory analysis, the rice bran brownies
made from potato flour had the lowest score in terms of acceptance towards
texture parameter, this could be caused because the rice bran brownies produced
from potato flour had harder texture compared to the others. According to Preedy
(2011), potato flour had been utilized to produce flat bread, which was an
unleavened product. The utilization of potato flour in the making of flat bread
could possibly be correlated with its effect toward the hardness of bakery
products. Singh et al (2005) also stated that potato flour had different size of
starch granules which varied according to its cultivars. Potato flour which has
smaller starch granules would produce harder and more cohesive product, this
could be an explanation why the rice bran brownies made from potato flour had
higher level of hardness compared to the others.
The low hardness level of rice flour could be caused by the protein
content of rice flour. As stated by Muksprasirt (2001), rice flour has lower level of
protein compared to wheat flour, therefore the hardness of the rice bran brownies
made from rice flour was lower and significantly different compared to rice bran
brownies made from wheat flour. This was also supported by the theory stated by
38
Hui et al (2008) that in the making of cake, flour which has low level of protein
would produce softer texture.
The hardness parameter of rice bran brownies made using wheat flour
and cassava flour was not significantly different and this could be correlated with
the result of the sensory analysis in term of texture parameter. In the sensory
analysis, the acceptance toward texture parameter of rice bran brownies made
from cassava flour and wheat flour was not significantly different and it could be
assumed that it was not significant different because basically the texture profile
of those two products was not significantly different as resulted from the objective
measurement using texture analyzer.
4.1.2.2 Moisture Content
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.6 Moisture Content of Rice Bran Brownies
The moisture content of rice bran brownies made using different types
of flour was analyzed in this preliminary research. Moisture content is an 39
important parameter to determine the quality of bakery products, such as
brownies.
Moisture content of the bakery product would affect the eating quality
of the finished products, as stated by Hui et al (2008). The moisture content of
rice bran brownies made using different types of flour could be seen in the Figure
4.6.
The moisture content of rice bran brownies made from different types
of flour was statistically analyzed using one way ANOVA, and from the ANOVA
table it was resulted that there was a significant difference between rice bran
brownies made from different types of flour towards the moisture content. From
Figure 4.6 it could be seen that the highest level of moisture content was given by
rice bran brownies made using rice flour, and the lowest one was the rice bran
brownies made using potato flour.
As shown in Figure 4.6, all of the rice bran brownies made with
different types of flour were significantly different towards each other, prior to
this it could be inferred that each of the rice bran brownies possessed different
characteristics because Hui et al (2008) stated that the amount of water could
affect the texture and mouth feel of bakery products. The low level of moisture
content given by the rice bran brownies made using potato flour could be
correlated with the result of texture analysis, whereas the hardness of the rice bran
brownies made using potato flour was the least among the others. This assumption
was supported by theory stated by Kilcast (2004) about the relation between
moisture content and the hardness of food products whereas loss of moisture
could increase the hardness of bakery products. The presence of water is also very 40
important in baking because it is essentially needed in order to gelatinize the
starch during heating, besides it also plays an important role by interact with
proteins in order to give desirable features for bakery products (Hui et al, 2008).
The moisture content of rice bran brownies made using rice flour was higher and
significantly different with rice bran brownies made using rice flour, according to
the research conducted by Park et al (2002) and Nura (2011), the ability of rice
flour to absorb water is higher compared to that in wheat flour.
4.1.2.3 Water Activity
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.7 Water Activity of Rice Bran Brownies
Water activity was one of the observed parameter in this preliminary,
because water activity was considered as an important parameter to the quality of
rice bran brownies. As stated by Hui et al (2008), water activity has a relationship
with moisture content, and furthermore, in bakery products water provides
lubrication when the bakery product is being eaten and affects its texture. This
41
Types of Flour0.61
0.62
0.63
0.64
0.65
0.66
0.67
0.68
0.69
0.663a0.667a
0.681b
0.634c
Wheat FlourCassava FlourRice FlourPotato Flour
theory also supported by another theory stated by Barbaso-Canovas (2007) which
stated that water activity affects the textural properties of foods, foods with high
Aw have moist and juicy texture, while foods with lower Aw have harder and
tougher texture.
The water activity of rice bran brownies made using different types of
flour could be seen in Figure 4.7. The water activity of rice bran brownies made
from different types of flour was statistically analyzed using one way ANOVA,
and from the ANOVA table it was resulted that there was a significant difference
between rice bran brownies made from different types of flour towards its water
activity. From Figure 4.7 it could be seen that the highest level of water activity
was given by rice bran brownies made using rice flour, and the lowest one was the
rice bran brownies made using potato flour. As show in Figure 4.7, all of the rice
bran brownies product had water activity value ranged from 0.634 – 0.681,
according to Barbosa-Canovas (2007), foods which have water activity values
from 0.6 – 0.9 are categorized as intermediate moisture foods. It could be
concluded that all of the rice bran brownies product, either made from rice flour,
wheat flour, potato flour or cassava flour were categorized as intermediate
moisture foods. The highest water activity was given by the rice bran brownies
made using rice flour, and it could be related with the moisture content of the rice
bran brownies made using rice flour which was also the highest compared to the
others as shown in Figure 4.6. On the other hand, the least water activity was
given by rice bran brownies made from potato flour, and it also could be related
with its moisture content which was also the least among the others as shown in
42
Figure 4.6. Therefore, the result was quite coherent with the theory stated above
about the relation between water activity and moisture content.
4.1.3 Determination of the Best Gluten Free Flour in the Making of Rice
Bran Brownies
The best gluten free flour in the making of rice bran brownies was
determined by means of sensory analysis. From the result of sensory analysis, for
the overall parameter, the rice bran brownies which had the highest sensory
acceptance was the rice bran brownies made using wheat flour, and the second
one was the rice bran brownies made using cassava flour. From the statistical
analysis, the consumer acceptance of rice bran brownies made from wheat flour
and rice bran brownies made from cassava flour was not significantly different, so
it could be concluded cassava flour could be used as the wheat flour replacer in
the making of rice bran brownies. This also supported by the result of objective
analysis, whereas the hardness of rice bran brownies made from cassava flour and
wheat flour was not significantly different. From the preliminary research, it could
be concluded that among rice flour, potato flour, and cassava flour, cassava flour
incorporation in rice bran brownies as wheat flour replacer would give the best
characteristic and consumer acceptance, therefore, cassava flour was determined
as the best gluten free flour in the making of rice bran brownies. Prior to the result
of the preliminary research, cassava flour would be used in the making of rice
bran brownies in the main research.
4.2 Main Research
43
The main research was conducted to determine the best rice bran
concentration and the best baking time in the making of rice bran brownies. The
rice bran brownies was made using cassava flour, which was selected from the
result of the preliminary result. The rice bran concentration which was
incorporated as the substitute for cassava flour consists of five different
concentrations which were 0%, 10%, 20%, 30%, and 40%, while the baking time
was 35, 45 and 55 minutes. The subjective and objective test were conducted to
analyze the rice bran brownies which were made using different rice bran
concentrations and different baking time. The subjective test that was conducted
was sensory evaluation using hedonic test. The hedonic test was conducted in
order to determine the best rice bran brownies formulation. There were four
quality parameters of the hedonic test which was observed, which was aroma,
taste, texture and overall acceptance of the rice bran brownies. The objective
analysis was conducted to observe several physical and chemical parameters
which consist of moisture content, water activity and the texture of rice bran
brownies.
4.2.1 Sensory Analysis
The determination of the best rice bran concentration and the best
baking time in the making of rice bran brownies was conducted based on sensory
evaluation procedure. The hedonic test was conducted using 70 panelists. The
panelists were untrained panelists and the panelists were asked to evaluate each of
the rice bran brownies samples using a 7 points hedonic scale. The scale was
ranged from 1 to 7, 1 stands for extremely dislike and 7 stands for extremely like.
The evaluation of each samples were done based on the preference of the panelists 44
toward each samples. All of data obtained from the hedonic test were analyzed
using the IBM SPSS 19 utilizing the one way ANOVA.
4.2.1.1 Aroma
Aroma was chosen as one of the parameter in the hedonic test to observe the
consumer preference towards the different concentration of rice bran and different
baking time incorporated during the making of rice bran brownies.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.8 Effect of Rice Bran Concentration Towards Aroma Parameter
The result of the effect of rice bran concentration toward the consumer
acceptance of aroma could be seen in Figure 4.8. From the statistical analysis
using two factor ANOVA, there was an effect of rice bran concentration towards
the consumer acceptance of rice bran brownies in terms of aroma, and as shown in
Figure 4.8, there was a significant different of the rice bran brownies made using
different concentration of rice bran towards the consumer acceptance in term of
45
Rice Bran Concentration4
4.2
4.4
4.6
4.8
5
5.2
5.4
5.1667a
4.9714ab 4.9381ab
4.8b
4.4762c
0%10%20%30%40%
aroma parameter. The highest acceptance was given by rice bran brownies made
with 0% rice bran concentration and the lowest acceptance was given by rice bran
brownies made with 40% rice bran concentration. From Figure 4.8, it also could
be seen that there was not a significant different between rice bran brownies made
using 0,10, and 20% rice bran concentration. Rice bran brownies made using 40%
of rice bran concentration was significantly different with rice bran brownies
made using 0,10,20 and 30% rice bran concentration.
There was a research conducted by Caesario (2011) which was
incorporation of rice bran in the meat ball. In that research, increasing the rice
bran concentration resulted in the decreasing of the consumer acceptance toward
aroma parameter, therefore it was coherent with the result of this research.
Kusumasari (2011) also incorporated rice bran in the making of ready to eat
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.9 Effect of Baking Time Towards Aroma Parameter
46
Baking Time4.7
4.75
4.8
4.85
4.9
4.95
5
4.3a
2.4a
2a
35 Minutes45 Minutes55 Minutes
breakfast cereal, and at certain point of rice bran addition, decreasing of consumer
acceptance towards aroma parameter was occurred. The decreasing of the
consumer acceptance in term of aroma parameter as the rice bran concentration
increased could be attributed to the unpleasant odor which was possessed by rice
bran as stated by Kaewka (2009), it also supported by another theory by
Sukonthara (2009) which stated that rice bran had several volatiles compound
contributed to its unpleasant aroma.
The result of the effect of baking time toward the consumer
acceptance of aroma could be seen in Figure 4.8. According to Hui et al (2008),
the production of aromatic compounds in bakery products is related to the baking
process, therefore baking time is one of the important consideration which will
determine the quality of bakery products. However, from the statistical analysis
using two factor ANOVA, there was no effect of baking time towards the
consumer acceptance of rice bran brownies in terms of aroma, and as shown in
Figure 4.8, there was no significant different of the rice bran brownies made using
different baking time towards the consumer acceptance in term of aroma
parameter.
The result of the interaction of rice bran concentration and baking
time toward the consumer acceptance of aroma could be seen in Table 4.1. From
the statistical analysis using two factor ANOVA, there was interaction between
rice bran concentrations and baking time towards the consumer acceptance of rice
bran brownies in terms of aroma, and as shown in Table 4.1, there was significant
different of the rice bran brownies made using different rice bran concentrations
and different baking time towards the consumer acceptance in term of aroma
47
parameter. The rice bran brownies made using 30% rice bran concentration and
baked for 35 minutes gave lower and significantly different value compared to
that which baked for 45 minutes, and so rice bran brownies made using 10 % rice
bran concentration which baked for 35 minutes gave lower and significantly
different value compared to that which baked for 45 minutes.
Table 4.1 Interaction of Rice Bran Concentration and Baking Time towards Aroma Parameter
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely like
From those results, it might be assumed that increasing the baking
time would affect the volatile compounds of rice bran which was attributed to the
aroma of the rice bran brownies as stated in theory above by Sukonthara (2009).
4.2.1.2 Taste
Taste was chosen as one of the parameter in the hedonic test to observe the
consumer preference towards the different concentration of rice bran and different
baking time incorporated during the making of rice bran brownies. The result of
the effect of rice bran concentration toward the consumer acceptance of taste
could be seen in Figure 4.9. From the statistical analysis using two factor
ANOVA, there was an effect of rice bran concentration towards the consumer
acceptance of rice bran brownies in terms of taste.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05
48
The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.10 Effect of Rice Bran Concentrations Towards Taste Parameter
As shown in Figure 4.10, there was a significant different of the rice
bran brownies made using different concentration of rice bran towards the
consumer acceptance in term of taste parameter. The highest acceptance was
given by rice bran brownies made with 0% rice bran concentration and the lowest
acceptance was given by rice bran brownies made with 40% rice bran
concentration. From Figure 4.10, it also could be seen that there was no
significant different between rice bran brownies made using 20 and 30% rice bran
concentration. Rice bran brownies made using 40% of rice bran concentration was
significantly different with rice bran brownies made using 0,10,20 and 30% rice
bran concentration. From the result, it could be assumed that increasing the rice
bran concentration would reduce the consumer acceptance of rice bran brownies
regarding its taste parameter, this also coherent with the research conducted by
Huang et al (2005) about the incorporation of rice bran in the pork meatballs. In
that research, the increasing of rice bran concentration lowered the consumer
49
Rice Bran Concentration0
1
2
3
4
5
6
5.2429a
4.7b4.3952c
4.1857c
3.7238d0%10%20%30%40%
acceptance towards taste parameter. The taste of rice bran brownies product might
be affected by several aromatic compounds contained in rice bran, which has been
studied and characterized by Jarunrattanasri (2004). Hui et al (2008) also stated
that there is correlation between aromatic compounds toward sensory perception
of taste. Luh (1991) stated that the dominant flavor characteristics of rice bran are
sweet taste which is attributed to high sugar content in bran and bitter taste which
is attributed to saponins content in rice bran. The decreasing of consumer
acceptance in term of taste parameter as the rice bran concentration increasing
could be affected by the unpleasant flavor given by rice bran prior to the flavor
profile described above.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.11 Effect of Baking Time Towards Taste Parameter
The result of the effect of baking time toward the consumer
acceptance of taste could be seen in Figure 4.11. From the statistical analysis
50
Baking Time4.25
4.3
4.35
4.4
4.45
4.5
4.55
4.6
4.4429a
4.5429a
4.3629a
35 minutes45 minutes55 minutes
using two factor ANOVA, there was no effect of baking time towards the
consumer acceptance of rice bran brownies in terms of taste
As shown in Figure 4.11, there was no significant different of the rice
bran brownies made using different baking time towards the consumer acceptance
in term of taste parameter. There was no interaction between rice bran
concentrations and baking time towards the consumer acceptance of rice bran
brownies in term of taste parameter.
4.2.1.3 Texture
Texture was chosen as one of the parameter in the hedonic test to
observe the consumer preference towards the different concentration of rice bran
and different baking time incorporated during the making of rice bran brownies.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.12 Effect of Rice Bran Concentration Towards Texture Parameter
51
Rice Bran Concentration3.6
3.8
4
4.2
4.4
4.6
4.8
54.8952a
4.5667b 4.5762b
4.4238b
4.119c
0%10%20%30%40%
The result of the effect of rice bran concentration toward the consumer
acceptance of texture could be seen in Figure 4.12. From the statistical analysis
using two factor ANOVA, there was effect of rice bran concentration towards the
consumer acceptance of rice bran brownies in terms of texture.
As shown in Figure 4.12, there was significant different of the rice
bran brownies made using different concentration of rice bran towards the
consumer acceptance in term of texture parameter. The highest acceptance was
given by rice bran brownies made with 0% rice bran concentration and the lowest
acceptance was given by rice bran brownies made with 40% rice bran
concentration. From Figure 4.8, it also could be seen that there was no significant
different between rice bran brownies made using 10, 20 and 30% rice bran
concentration. This result was coherent with the research conducted by Huang et
al (2005), in that research the increased rice bran concentration lowered the
consumer acceptance of the pork meatball products in term of texture parameter.
This result was also supported by another research conducted by Delahaye et al
(2005) which was the study of rice bran utilization in frozen pizza. Sensory
analysis was conducted to determine the consumer acceptance of frozen pizza,
and textural acceptance was one of the parameter observed in the sensory analysis,
which specifically was hardness. The research resulted with lowered sensory
acceptance toward the hardness parameter as the rice bran concentration
increased.
The result of the effect of baking time toward the consumer
acceptance of texture could be seen in Figure 4.11. From the statistical analysis
52
using two factor ANOVA, there was effect of baking time towards the consumer
acceptance of rice bran brownies in terms of texture.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.13 Effect of Baking Time Towards Texture Parameter
As shown in Figure 4.13, there was significant different of the rice bran brownies
made using different baking time towards the consumer acceptance in term of
texture parameter. The highest acceptance was given by rice bran brownies baked
in 45 minutes and the lowest acceptance was given by rice bran brownies baked in
55 minutes, however there was no significant different between rice bran
brownies baked in 55 minutes and 35 minutes towards the consumer acceptance
regarding texture parameter. According to Hui et al (2008), there are many
features which are occurred during baking such as Maillard reaction, starch
gelatinization, and moisture loss. These occurrences could possibly affect the
texture of the final product which could affect the consumer preference toward the
texture of the rice bran brownies.
Table 4.2 Interaction of Rice Bran Concentration and Baking Time towards Texture Parameter
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely like
From the statistical analysis using two factor ANOVA, there was
interaction between rice bran concentrations and baking time towards the
consumer acceptance of rice bran brownies in term of texture, and as shown in
Table 4.2, there was significant different of the rice bran brownies made using
different rice bran concentrations and different baking time towards the consumer
acceptance in term of texture parameter.
4.2.1.4 Overall
The overall acceptance parameter was chosen as one of the parameter
to be evaluated in the hedonic test as its importance to determine the preference of
the consumer towards the rice bran brownies product in terms of combined
evaluation regarding the aroma, taste and texture of the rice bran brownies. The
result of the effect of rice bran concentration toward the consumer acceptance of
overall parameter could be seen in Figure 4.14. From the statistical analysis using
two factor ANOVA, there was effect of rice bran concentration towards the
consumer acceptance of rice bran brownies in terms of overall parameter.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely like
54
Figure 4.14 Effect of Rice Bran Concentration Towards Overall Parameter
As shown in Figure 4.14, there was significant different of the rice
bran brownies made using different concentration of rice bran towards the
consumer acceptance in term of overall parameter. The highest acceptance was
given by rice bran brownies made with 0% rice bran concentration and the lowest
acceptance was given by rice bran brownies made with 40% rice bran
concentration. From Figure 4.14, it also could be seen that there was no
significant different between rice bran brownies made using 10, 20 and 30% rice
bran concentration. This result was similar with the research conducted by Huang
et al (2005) about the utilization of rice bran in the making of pork meatballs. In
that research, increasing the concentration of rice bran would reduce the overall
acceptance of the pork meatballs.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05
55
Rice Bran Concentration0
1
2
3
4
5
6
5.1571a4.8b
4.5619b 4.5524b
3.919c
0%10%20%30%40%
The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely likeFigure 4.15 Effect of Baking Time Towards Overall Parameter
The result of the effect of baking time toward the consumer overall
acceptance could be seen in Figure 4.15. From the statistical analysis using two
factor ANOVA, there was no effect of baking time towards the consumer
acceptance of rice bran brownies in term of overall parameter.
The result of the interaction of rice bran concentration and baking
time toward the consumer acceptance of overall parameter could be seen in Table
4.3. From the statistical analysis using two factor ANOVA, there was interaction
between rice bran concentrations and baking time towards the consumer
acceptance of rice bran brownies in terms of overall parameter, and as shown in
Table 4.3, there was significant different of the rice bran brownies made using
different rice bran concentrations and different baking time towards the consumer
acceptance in term of overall parameter parameter.
56
Baking Time4.48
4.5
4.52
4.54
4.56
4.58
4.6
4.62
4.64
4.66
4.6a
4.6514a
4.5429a
35 minutes45 minutes55 minutes
Table 4.3 Interaction of Rice Bran Concentration and Baking Time towards Texture Parameter
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05The range of hedonic scaling : 1=extremely dislike, 2=dislike, 3=slightly dislike, 4=neutral, 5=slightly like, 6=like, 7=extremely like
From the statistical analysis using two factor ANOVA, there was
interaction between rice bran concentrations and baking time towards the overall
acceptance of rice bran brownies, and as shown in Table 4.3, there was significant
different of the rice bran brownies made using different rice bran concentrations
and different baking time towards the consumer acceptance in term of overall
parameter. From the Table 4.3, the rice bran brownies which gave the highest
acceptance was the rice bran brownies made with 0% rice bran and 35 minutes
baking time, which was not significantly different with rice bran brownies made
with 0% rice bran and 45 minutes baking time. Rice bran brownies made with
10% rice bran and 35 minutes baking time, 10% rice bran and 45 minutes baking
time, 10% rice bran and 55 minutes baking time, 30% rice bran and 55 minutes
baking time and 0% rice bran and 45 minutes baking time were not significantly
different as can be seen in the Table 4.3. Therefore it could be assumed, that
increasing the rice bran concentration in the making of rice bran brownies up to
30% concentration would produce rice bran brownies which was still acceptable
for the consumer.
57
4.2.2 Physical Analysis
4.2.2.1 Texture
The texture of rice bran brownies made using different rice bran
concentration and different baking time analyzed using texture analyzer. The
textural parameter which was observed was hardness parameter. The result of the
effect of rice bran concentration toward the hardness parameter could be seen in
Figure 4.16.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.16 Effect of Rice Bran Concentration Towards Hardness Parameter
From the statistical analysis using two factor ANOVA, there was
effect of rice bran concentration towards the hardness parameter of rice bran
brownies. As shown in Figure 4.16, there was significant different of the rice bran
brownies made using different concentration of rice bran towards the hardness
parameter. The highest value of hardness was given by rice bran brownies made
with 40% rice bran concentration and the lowest one was given by rice bran
58
Rice Bran Concentration0
1000
2000
3000
4000
5000
6000
7000
8000
6050.522a6363.705ab
7073.377bc 6910.001bc
7535.644c
0%10%20%30%40%
brownies made with 0% rice bran concentration. From Figure 4.16, It could be
seen that as the rice bran concentration increased the value of hardness also
increased. The hardness value of rice bran brownies made with 40% rice bran
concentration was higher and significantly different compared to the rice bran
brownies made with 0 and 10% rice bran concentration, however it was not
significantly different with rice bran brownies made with 20 and 30% rice bran
concentration. This result is similar with several result which was already
conduced, regarding the incorporation of rice bran in the food products. Huang et
al (2005) studied the effect of rice bran concentration towards the hardness of
pork meatballs, and it resulted in the increasing of hardness value as the rice bran
concentration increased. Another research was conducted by Sairam et al (2011),
and showed similar result, in that research the rice bran was incorporated in the
bread making, and as the rice bran concentration increased, the value of hardness
also increased. Therefore it could be assumed that the rice bran concentration had
positive correlation toward the increasing of the hardness value in a food product.
59
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.17 Effect of Baking Time Towards Hardness Parameter
From the statistical analysis using two factor ANOVA, there was
effect of baking time towards the hardness parameter of rice bran brownies. As
shown in Figure 4.17, there was significant different of the rice bran brownies
made using different baking time towards the hardness parameter. The highest
value of hardness was given by rice bran brownies made with 55 minutes baking
time and the lowest value was given by rice bran brownies made with 35 minutes
baking time. From Figure 4.17, It could be seen that as the baking time increased
the value of hardness also increased. The hardness value of rice bran brownies
made with 55 minutes baking time was higher and significantly different
compared to the rice bran brownies made with 35 and 45 minutes baking time.
Hui et al (2008) stated that the duration of baking is related to the characteristic of
the finished product. During baking process, moisture loss is occurred gradually,
and this could be the cause why the hardness of the rice bran brownies increased
as the baking time increased. It could be assumed that as the baking time
increased, the moisture content decreased and therefore affected the textural
60
Baking Time5800
6000
6200
6400
6600
6800
7000
7200
7400
6366.126a
6778.847a
7214.977b
35 minutes45 minutes55 minutes
properties of the rice bran brownies, in term of hardness. From the statistical
analysis using two factor ANOVA, there was no interaction between rice bran
concentrations and baking time towards the hardness parameter of rice bran
brownies.
4.2.2.2 Moisture Content
The moisture content of rice bran brownies made using different rice
bran concentration and different baking time was analyzed. Moisture content was
considered as an important parameter in determining the quality of baking, as
stated by Hui et al (2008), water plays a major role during baking process because
water reacts with baking ingredients and evaporates when heated. The result of the
effect of rice bran concentration toward the hardness parameter could be seen in
Figure 4.18. From the statistical analysis using two factor ANOVA, there was
effect of rice bran concentration towards the moisture content of rice bran
brownies. It could be seen in Figure 4.18 that there was significant different of the
rice bran brownies made using different concentration of rice bran towards its
moisture content.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05
61
Figure 4.18 Effect of Rice Bran Concentration Towards Moisture Content
The highest moisture content was given by rice bran brownies made
with 40% rice bran concentration and the lowest one was given by rice bran
brownies made with 0% rice bran concentration. From Figure 4.18, It could be
seen that as the rice bran concentration increased the moisture content also
increased. The moisture content of rice bran brownies made with 40% rice bran
concentration was higher and significantly different compared to the rice bran
brownies made with 0, 10, 20, and 30% rice bran concentration. The moisture
content of rice bran brownies made using 30% rice bran concentration was not
significant different with the one made using 20% rice bran concentration,
however it was significant different with rice bran brownies made using 0 and
10% rice bran concentration. This result was coherent with the result which was
conducted by Saputra (2008), in that result rice bran was incorporated in cookies,
and by substituting wheat flour with 25 % rice bran in the cookies the moisture
content of the product was increased. Similar result was obtained from research
conducted by Delahaye (2005), whereas as the rice bran concentration increased
62
Rice Bran Concentration0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
12.96%a14.03%ab 14.48%bc
15.67%c
17.09%d
0%10%20%30%40%
the moisture content of the product was also increased. From this information, it
could be assumed that increasing the rice bran concentration might be contributed
in the increasing of moisture content in a bakery product.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.19 Effect of Baking Time Towards Moisture Content
The result of the effect of baking time toward the moisture content
could be seen in Figure 4.19. From the statistical analysis using two factor
ANOVA, there was effect of baking time towards the moisture content of rice
bran brownies. It could be seen in Figure 4.19 that there was significant different
of the rice bran brownies made using different baking time towards its moisture
content. As shown in Figure 4.19, Rice bran brownies made with 35 minutes
baking time gave the highest moisture content while the rice bran brownies made
with 55 minutes baking time gave the lowest moisture content. From Figure 4.19,
It could be seen that as the baking time increased the moisture content was
decreased. It could be correlated with the theory stated by Sakin et al (2007),
during baking moisture transfer is occurred, which consists of internal and surface
63
Baking Time0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2 18.77%a
14.31%b
11.46%c
35 minutes45 minutes55 minutes
evaporation. So it could be assumed that the prolonged baking time would reduce
the amount of moisture in bakery products. From the statistical analysis using two
factor ANOVA, there was no interaction between rice bran concentrations and
baking time towards the moisture content of rice bran brownies.
4.2.2.3 Water Activity
Water activity was one of the observed parameter in the making of
rice bran brownies, because water activity was considered as an important
parameter to the quality of rice bran brownies. As stated by Hui et al (2008),
water activity is a vital parameter for food monitoring, and the value of water
activity is related to the moisture content of the food product.
The result of the effect of rice bran concentration toward the water
activity could be seen in Figure 4.20. From the statistical analysis using two factor
ANOVA, there was effect of rice bran concentration towards the water activity of
rice bran brownies. It could be seen in Figure 4.20 that there was significant
different of the rice bran brownies made using different concentration of rice bran
towards its water activity. The highest water activity was given by rice bran
brownies made with 40% rice bran concentration and the lowest one was given by
rice bran brownies made with 10% rice bran concentration. From Figure 4.20, It
could be seen that as the rice bran concentration increased the water activity was
also increased.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05Figure 4.20 Effect of Rice Bran Concentration Towards Water Activity
Although the rice bran brownies made using 10% rice bran
concentration gave the lowest water activity among the others, from the statistical 64
analysis it was not significantly different with the rice bran brownies made using
10 and 20% rice bran concentration, however it was significant different with rice
bran brownies made using 30 and 40% rice bran concentration. This result could
be correlated with the moisture content of the rice bran brownies, as the rice bran
concentration increased, the moisture content was increased, therefore it could be
assumed that the increasing moisture content affect the water activity in rice bran
brownies, as stated in the theory above regarding the relation of moisture content
and water activity.
The result of the effect of baking time toward the water activity could
be seen in Figure 4.21. From the statistical analysis using two factor ANOVA,
there was effect of baking time towards the water activity of rice bran brownies.
Notes : Means followed by the same letter are not significantly different in Duncan Test at α=0.05
65
Rice Bran Concentration0.660
0.670
0.680
0.690
0.700
0.710
0.720
0.682a0.678a
0.690a
0.709b
0.713b
0%10%20%30%40%
Figure 4.21 Effect of Baking Time Towards Water Activity
The result of the effect of baking time toward the water activity could
be seen in Figure 4.21. From the statistical analysis using two factor ANOVA,
there was effect of baking time towards the water activity of rice bran brownies.
As shown in Figure 4.21, there was significant different of the rice bran brownies
made using different baking time towards its water activity. Rice bran brownies
made with 35 minutes baking time gave the highest water activity while the rice
bran brownies made with 55 minutes baking time gave the lowest water activity
value. From Figure 4.21, It could be seen that as the baking time increased the
water activity was decreased. This phenomenon could be correlated with the result
of the moisture content analysis, whereas it showed similar result. As the baking
time increased, the moisture content decreased. Since water activity had a
relationship with moisture content, it could be inferred that the decreasing of
water activity as the baking time increased was affected by the moisture content of
the food product. From the statistical analysis using two factor ANOVA, there
66
Baking Time0.650
0.660
0.670
0.680
0.690
0.700
0.710
0.7200.714a
0.692b
0.677c
35 minutes45 minutes55 minutes
was no interaction between rice bran concentrations and baking time towards the
water activity of rice bran brownies.
4.3 Proximate Analysis of Rice Bran Flour
The proximate analysis of rice bran flour was conducted to determine
the nutritional value of rice bran. The result of the proximate analysis could be
6.74 % protein content, 30.91 % fat content, 48.61 % carbohydrate content, and
7.79% dietary fiber content. The best gluten free rice bran brownies formulation
was considered as high fiber food because it contained more than 20% of dietary
fiber RDA per serving size.
5.2 Suggestion
Rice bran has already been incorporated in several food product, such
as brownies as done in this research. Further study on the shelf life of the product
made using addition of rice bran needs to be done. Furthermore, study towards
method to increase the shelf life stability of a food product with rice bran addition
also needs to be done, it might be possible that pre – treatment of the rice bran
before processing could affect the shelf life stability of the food product
incorporated with rice bran although it has not yet studied extensively.
Furthermore, a research about the optimization of the gluten free rice bran
brownies formulation could be conducted to increase the consumer acceptance
towards the gluten free rice bran brownies product.
71
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APPENDICES
76
Appendix A. Hedonic Test Questionnaire
QUESTIONNAIRE UJI HEDONIK
NAMA : TANGGAL :
SAMPEL : BROWNIES
Intruksi: Cicipilah sampel dari kiri ke kana sesuai kode sampel yang tertera pada kuesioner, lalu berikan penilaian berdasarkan aroma, rasa, warna, tekstur, dan penerimaan keseluruhan (berdasarkan tingkat kesukaan anda) dengan spontan tanpa membandingkan antar sampel. Bilaslah mulut dengan air mineral setiap selesai mencoba sampel. Pencicipan sampel dilakukan satu kali saja tanpa pengulangan. Terima kasih.
Kode SampelAromaRasaWarnaTeksturOverall
Keterangan :
1=sangat tidak suka 5=agak suka
2=tidak suka 6=suka
3=agak tidak suka 7=sangat suka
4=netral
77
Appendix B. Sensory Analysis Procedure
1. Hedonic Test (Meilgaard et al, 2007)
The hedonic test is a sensory evaluation method to determine the
consumer acceptance of the product based on the overall sensory qualities of the
food product. The hedonic test is done using scale from 1 to 7 (1 = extremely
Between Groups 25.554 3 8.518 4.355 .005Within Groups 539.871 276 1.956Total 565.425 279
TasteDuncana
Flour NSubset for alpha = 0.051 2
Potato 70 3.5857Rice 70 4.1000Cassava 70 4.2143Wheat 70 4.4000Sig. 1.000 .234Means for groups in homogeneous subsets are displayed.a. Uses Harmonic Mean Sample Size = 70.000.
91
Appendix G. Hedonic Test for Texture Parameter Result of The Preliminary
Between Groups 66.414 3 22.138 12.150 .000Within Groups 502.886 276 1.822Total 569.300 279
OverallDuncana
Flour NSubset for alpha = 0.051 2
Potato 70 3.9429Rice 70 4.2143Cassava 70 4.9143Wheat 70 5.1286Sig. .235 .348Means for groups in homogeneous subsets are displayed.a. Uses Harmonic Mean Sample Size = 70.000.
APPENDIX I. Texture Analysis of The Preliminary Research97