Comparative Analysis of Nutritional Value of Oreochromis ...

Research ArticleComparative Analysis of Nutritional Value ofOreochromis niloticus (Linnaeus) Nile TilapiaMeat from Three Different Ecosystems

Fanuel Jim1 Penina Garamumhango2 and Colin Musara1

1Department of Preclinical Veterinary Studies University of Zimbabwe PO Box MP 167 Mount Pleasant Harare Zimbabwe2Masvingo Polytechnic Department of Food Science PO Box 800 Masvingo Zimbabwe

Correspondence should be addressed to Colin Musara colmusvetuzaczw

Received 20 July 2016 Revised 7 October 2016 Accepted 24 October 2016 Published 12 January 2017

Academic Editor Alejandro Hernandez

Copyright copy 2017 Fanuel Jim et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Determination of protein lipid and mineral content of fish meat is necessary to ensure that it meets requirements for foodregulations and commercial specifications The objective of the present study was to determine the chemical composition ofOreochromis niloticus (L) Nile tilapia under three different ecosystems (1) high pollution and high density of Eichhornia crassipesthat is water hyacinth (Lake Chivero) (2) medium pollution and medium density of water hyacinth (Lake Manyame) and (3) lowpollution and low density of water hyacinth (Lake Kariba) Drymatter protein lipids and ashwere evaluated by proximate analysisMinerals were determined by atomic absorption spectrophotometry and pH was determined by a pH meter Lake Kariba fish hadthe highest percentage of dry matter protein and ash These qualities were correlated to low levels of pollutants and high oxygencontent in the harvest waters The phosphorus content of fish from Lake Chivero was very high in tandem with phosphate levelsin the harvest waters In addition water from Lake Chivero had an alkaline pH high nitrate and low oxygen content The resultssuggest that effluent from sewage works and fertilizer industries caused pollution and proliferation of water hyacinth contributingto pervasion of the chemical composition of fish

1 Introduction

Fish is the cheapest source of animal protein for somecommunities including those who do not consume red meatthe malnourished immunocompromised pregnant womenand nursing mothers Several species of fish have been partof the diet of some ethnic groups in all continents for along time Fishing makes the most widespread contributionto fish meat commercial fish farming is limited Due toits high protein content fish is commonly used as relishFish have a high economic value derived through operationof fisheries and aquaculture which provide employmentrecreation trade and economic well-being for those involvedin the trade Products from fishing are an important partof international trade currently worth more than US$50billion [1] Nutritionally fish is considered an important andrich source of affordable protein Fish consumption has beenreported to contribute to almost 50 of the animal protein

consumed in many Asian countries [2] Fish protein is char-acterized by a desirable composition of amino acids [3] Themuscle consists of mainly myofibrillar proteins sarcoplasmicproteins connective tissue stroma proteins polypeptidesnucleotides andnonprotein nitrogen compounds Fish is alsoa rich source of group B vitamins as well as vitamins A andD [4] Besides its acceptance as a balanced source of animalprotein and vitamins fish also provides polyunsaturated fattyacids (PUFAs) and minerals necessary for optimal health[5 6] Fish also generate scientific interest in the developmentand processing of high quality protein food which retainsits aroma appearance and colour Apart from being usedas food fish is also increasingly demanded for use as feedHowever nutritional advantages of fish are limited by itsrapidly perishable nature and therefore short shelf-life

Data concerning the chemical composition of fish isessential to provide information on nutritious healthy foodsof low fat and high protein content [7 8] In addition fatty

HindawiJournal of Food QualityVolume 2017 Article ID 6714347 8 pageshttpsdoiorg10115520176714347

2 Journal of Food Quality

acid composition data are needed by food scientists andnutritionists in dietary formulation food processing andproduct development [9]The study of chemical compositionof fish is important since it influences keeping quality andtechnological characteristics of the fish [10] Measurementof proximate profiles such as protein lipids and moisturecontent is often necessary to ensure that they meet therequirements of food regulations and commercial specifica-tions [11] They also influence postharvest processing and theshelf-life of the fish [12]

The nutritional composition of freshwater fish was foundto differ between geographical localities [13] The changingbiological and environmental conditions are a useful tool tothe ecologist Ecologists require information on meat com-position to help create or maintain dam water atmosphereconducive for rearing a quality fish meat carcass So farthere has been research on other effects on fish but notmuch research has been done on the nutritional quality ofthe fish living in different ecosystems The present studyaimed to investigate the impact of different water sourceson the quality of Oreochromis niloticus (Nile tilapia) fromthree different fresh water sources Oreochromis niloticusis a popular fish and in Zimbabwe exists in abundancein Lake Kariba Lake Chivero and Lake Manyame Thecatchment areas of the water sources are different LakeChiverorsquos catchment introduces industrial effluent and rawsewage waste into the lake from large urban centres nearbyLake Manyamersquos catchment area introduces 10 million litresof raw sewage into the lake from a neighbouring town everymonth The catchment area of Lake Kariba is relatively freefrom waste and pollution The quality of water is consideredthe main factor in fish quality and also affects reproductionof fish In addition continued deposition of effluent into LakeChivero has abetted the spread of water hyacinth (Eichhorniacrassipes) which thrives under constant supply of nitrates andphosphates in effluent from fertilizer industries Due to thespread of the water hyacinth the water in Lake Chivero tendsto be highly deoxygenated compared to LakeManyamewherethe weed is less prevalent The water in Lake Kariba tends tobe highly oxygenated as the water hyacinth is scant and onlypresent in shallow water

2 Material and Methods

21 Description of Study Site The fish used in this study weresourced from three different ecosystems The description ofthe three water bodies is shown in Table 1

Figure 1 shows the schematic catchment areas for LakeManyame and Lake Chivero The catchment for Lake Karibastraddles a wide area within southern Africa and parts of eastAfrica

22 Collection of Water and Fish Samples Water and fishsamples were collected on the same day A total of 30 samplesof fish were collected comprising ten fish from each lakecaught using the seine netting and gill netting method Thefish were placed in ice soon after the catch to keep them fresh

Table 1 Description of Lake Chivero Lake Kariba and LakeManyame

Lake Surfacesize Climaterainfall Catchment

area

Kariba 5 580 km2 Hot temperaturesthroughout the year 1 352 000 km2

Chivero 2630 km2

NovemberndashMarchhotrainy MayndashAugust

cold and drySeptember-October hot

and dry

2 300 km2

Manyame 81 km2 Similar to Lake Chivero Same as LakeChivero

Water samples were collected with a Ruttner samplermounted to a speed boat using the integrated surface downprofile method to obtain a representative water sample [14]The water was collected into duplicate sterile sample bottleschilled in ice and transported to the laboratory for analysisBoth the fish and water samples were sent to the Departmentof Animal Science and the Department of Biological SciencesLaboratories at the University of Zimbabwe for analysis

23 Preparation and Analysis of Water Samples A portionof the water sample was vacuum pumped to pass througha Millipore glass fibre prefilter (GFP) for the analysis ofdissolved components The water was analysed for dissolvedoxygen phosphates nitrates and pHusing standardmethodsfor fresh water analysis as described previously [15]

24 Laboratory Analysis of Fish Samples Fish samples weresubjected to proximate analysis as described by the Associa-tion of Official Analytical Chemists (AOAC) [16]

241 Fish Sample Preparation Samples for fish analysiswere taken from the left side of each fish Samples werehomogenised by passing them twice through a mincerwith 4mm holes and mixed thoroughly Uniformity of thehomogenate was ensured by further mixing with a domesticfood processor The resultant homogenate was packed intoseveral small convenient sterile containers and stored at 0∘Cprior to laboratory analysis

242 Protein Analysis This was determined using the Kjel-dahl process as described by AOAC To 2 g of appropriatelyhomogenised fish sample weighed into a Kjeldahl flask 10 gof catalyst 25mL of concentrated H2SO4 and three glassbeads were added The contents were then digested with amixture of powdered potassium sulphate copper sulphateand selenium mixed in the ratio of 948 5 02 until beingclear Contents were cooled and diluted and 100mL of 40sodium hydroxide was added Exactly 50mL of 4 boricacid was poured into a separate conical flask and connectedto the distillation unit The mixture was distilled and thedistillate was collected into the boric acid containing 3 dropsof indicator until the volume was above 150mL Ammoniawas converted to ammonium metaborate and titrated with

Journal of Food Quality 3

0 10 20

(km)

Scale

North

30∘45998400E

30∘45998400E

18∘00

998400S18∘00

998400S

31∘00998400E

31∘00998400E

Figure 1 A schematic representation of the catchment area of Lake Manyame and Lake Chivero

standardized 01M hydrochloric acid The percentage ofprotein was calculated using the following formula

Protein

=(titre vol sample minus titre vol blank) times 0014 times 01 times 625

weight of sample used

times 100

(1)

The sample was analysed in triplicate

243 Analysis of Crude Fat Crude fat was analysed usingthe ether extract method A 2 g dried fish sample wasinserted into a predried porous thimble allowing rapidflow of petroleum ether The sample was wrapped in filterpaper placed into the thimble and covered with glass woolAnhydrous ether was placed into a weighed boiling flaskwhich together with the Soxhlet flask and condenser was

assembled into the Soxhlet apparatus Fat was extracted into aSoxhlet extractor for 6 hours by heating solvent in the boilingflask The boiling flask with extracted fat was dried in an airoven at 100∘C for 30 minutes cooled in a desiccator andweighed The fat content was estimated as follows

Fat

=weight of flask and extracted fat minus weight of empty flask

weight of dried sample used

times 100

(2)

244 Determination of Dry Matter Moisture was deter-mined using the AOAC method of proximate analysisExactly 05 g of homogenised fish sample taken in triplicatewas placed in a preweighed aluminium dish and placed in ahot air oven maintained at 105∘C for 1 hour The sample wascooled in a desiccator to room temperature and the loss inweight was calculated as a percentage as follows

Moisture =(weight of sample before drying minus weight of sample after drying)

weight of sample before dryingtimes 100 (3)


Table 2 Quality of water from Lakes Chivero Manyame andKariba

Lake Dissolvedoxygen mgL

PhosphatesmgL

NitratesmgL pH

Kariba 1100 658 015 760Manyame 970 037 180 678Chivero 740 2713 3260 971

245 Measurement of Ash Content A 5 g fish sample takenin triplicate was weighed into an empty preweighed crucibleand placed in a muffle furnace which was then ignitedfor 12 hours at 550∘C The furnace was turned off tocool to 250∘C before sample removal Sample was desic-cated prior to weighing The ash content was calculated asfollows

Ash =(weight of crucible plus sample after ashing minus empty weight of crucible)

weight of sample before ashingtimes 100 (4)

246 Evaluation of Minerals Mineral content was deter-mined from the ashed sample using an atomic absorptionspectrophotometer The minerals analysed were calciumiron potassium magnesium zinc sodium phosphate cad-mium and copper The minerals constituents were in partsper million which was converted by calculation to mg100 g

247 Measurement of pH Measurements of the pH of fishmeat were performed with a Jenaway 8014 pH meter byplacing the glass-calomel electrodes into a suspension of 1gram of fish flesh in 100mL of distilled water

25 Data Analysis Data on chemical composition of fish wasentered in Excel and analysed using the Statistical AnalysisSystem Version 93 SAS 2010 Data was analysed using thegeneralized linear models procedure (PROC GLM) of SASMeans were separated using the ldquolsmeansrdquo methodologyThefollowing model was used

119884119894119895 = 120583 + 119879119894 + 119890119894119895 (5)

where 119884119894119895 is the observation on the 119895th fish 120583 is the mean dueto conditions common to all observations 119879119894 is the effect ofthe 119894th source of fish (119894 = 1 2 3) 119890119894119895 are the random residuals

3 Results

31 Quality of Water Table 2 shows the amount of dissolvedoxygen phosphates and nitrates as well as the pH of thewater from the three sources Water from Lake Kariba hadthe highest concentration of dissolved oxygen with LakeManyame and Lake Chivero waters having much less Onthe other hand the concentrations of phosphates and nitrateswere much higher in Lake Chivero in comparison to LakesManyame and Kariba The pH of water from Lake Chiverowas also higher than that of water from the other two sources

32 Quality of Fish Below are the descriptive statistics andresults of analysis of the fish from the three sources

321 Effect of Source of Fish on Dry Matter Protein Fat andpH of Fish Meat Results for dry matter protein fat and pHare presented in Table 3 The dry matter content fat protein

and pHwere significantly (119875 lt 005) influenced by the sourceof the fish Fish fromLake Kariba had the highest levels of drymatter ash and protein but they were significantly lower infat than fish from Lake Chivero although similar to fish fromLake Manyame The pH of fish from Lake Kariba was lowerthan that of the fish from Lake Chivero but similar to that offish from Lake Manyame

322 Effect of Source of Fish on Mineral Content of FishTable 4 shows the results of ash and mineral analysisAlthough source of fish had a significant effect on the overallash content of the fish meat it had no effect (119875 gt 005)on calcium sodium iron zinc and copper content of thefish However the content of magnesium potassium andphosphorus were significantly (119875 lt 005) influenced bythe source of the fish Meat of fish from Lake Chivero wasgenerally higher (119875 lt 005) in the content of magnesium andphosphorus

4 Discussion

41 Differences in Chemical Composition of Fish Meat accord-ing to Source Protein content of fish from all three lakesranged between 1386 and 1712 with Lake Kariba havingthe highest and Lake Manyame the least Protein contentin Lake Manyame fish (1386) was lower than the averageof 15minus24 [17] The results suggest that the Oreochromisniloticus fromLake Chivero and Lake Kariba was an adequatesource of protein which makes Oreochromis niloticus fromthese lakes an important source of dietary protein similarto other sea and fresh water fish [18] However the proteincontent of Oreochromis niloticus from Lake Manyame wasslightly below 15 and therefore slightly inadequate Lipidcontent is used to classify fish [9] The fat content of fish inLake Kariba and Lake Manyame which was 174 and 173respectively classifies the flesh as lean and the fat contentin Lake Chivero fish flesh which was 317 is classified aslow fat The normal lipid content of Oreochromis niloticusis 275 plusmn 016 [19] Hence Lake Chivero fish contained ahigher percentage of lipids whereas fish from the other twolakes had much less Normally high-lipid fishes have lesswater and more protein than low-lipid fishes Fish from LakeChivero showed this kind of relationship However fish from


Table 3 Ls mean dry matter ash fat protein and pH of fish (se in parentheses)

Source lake Dry matter

Ash

Fat

Protein pH

Kariba 2470a (0725) 330a (0304) 174a (0335) 1712a (0503) 617a (0111)

Manyame 1918b (0725) 176b (0304) 173a (0335) 1386b (0503) 606a (0111)

Chivero 2248a (0725) 227c (0304) 317b (0335) 1645a (0503) 658b (0111)

Means with different superscripts within column are significantly different from each other

Table 4 Ls mean ash () and mineral (mg100 g) content of fish from three water bodies

Source lake Ash Mg K P Ca Na Fe Zn CuKariba 330a 2417a 38717a 17500a 5900a 1833a 450a 095a 071a

Manyame 176b 1883a 31933b 5833b 3867a 1433a 317a 116a 048a

Chivero 227c 4600b 42933a 30833c 3317a 1800a 317a 122a 035a

se 034 4769 17181 10758 9040 1151 054 0143 0097


Lake Kariba also exhibited higher protein levels althoughthey had lower lipid content In Lake Chivero fish had 317fat against a protein content of 1645 whereas Lake Karibafish had 174 fat value against a protein content of 1712The analysis results indicate that the Oreochromis niloticusfrom all sources had normal amounts of essential mineralsnamely calcium potassium sodium phosphorus copperand ironHenceOreochromis niloticus fromall three lakeswasan adequate source of minerals just like most species of fish[20]The normal ash content ofOreochromis niloticusmeat is26plusmn02 [19] Total mineral content (ash) was above averagein fish from Lake Kariba and lower than normal in LakeManyame fish with fish from Lake Chivero in the medianrange However fish from Lake Chivero had more contentin their flesh of magnesium and phosphorus Normal levelsof magnesium and phosphorous in Oreochromis niloticusmeat are 27mg100 g and 170mg100 g respectively [21]values which are substantially lower than the 4600mg100 gand 30833mg100 g recorded in the present study Normalmoisture content of meat from Oreochromis niloticus wasfound to be 789 plusmn 05 giving a dry matter value of 211 plusmn05 [19] Of the three sources only fish from LakeManyamehad a subnormal dry matter composition

42 Review of Factors Affecting the Chemical Composition ofFish Meat Differences in nutritional components of the fishcould be as a result of the rate at which these components areavailable in the particular water body [22] They could alsobe due to the capacity of the fish to absorb and assimilate theessential nutrients from the harvest water where they habitator the available diet [23] Oreochromis niloticus is an omni-vore The diet comprises a diversity of food items includingmacrophytes [24] algae zooplankton insects oligochaetescaridina and bivalves [25]Whereas large zooplankton formsa significant component of the diet of Oreochromis niloticusthere is nonselective filtration of smaller phytoplanktonorganisms during feeding [26] The nutritional componentsof freshwater fish differ between geographical localities [13]

Protein content is also negatively affected by the fishrsquosspawning period [27] The flesh lipid is controlled by theavailable nutrition [28 29] Other factors could also comeinto play These include the feeding frequency sex andmaturity of the fish [30 31] Theminerals composition of fishmeat is determined by the harvest waters The concentrationof minerals in the harvest waters influences the content ofthose minerals in the habitat fish

43 Influence of Ecosystem on Chemical Composition of FishMeat from Lakes Chivero Manyame and Kariba In thepresent study the most probable reason for the differencesobserved in fish from the three ecosystems was pollution ofsewer and industrial effluents from large neighbouring urbancentres into Lake Chivero and Lake Manyame That in turncaused higher amounts of nutrients in the waters leadingto increased growth of water hyacinth that decreased theconcentration of dissolved oxygen in the water Consequentlythe chemical composition of fish from the two sourceswas negatively affected Water hyacinth an exotic floatingmacrophyte was introduced into Zimbabwe in 1937 Growthof water hyacinth is influenced chiefly by the concentrationsof phosphorous and nitrogen in the aquatic environment[32] Maximum growth has been recorded in water fertilizedwith sewage effluent (219ndash657 tonneshayear) as opposedto water with artificial fertilizers (756ndash1911 tonneshayear)[33] Unabated inflow of sewer effluent into Lake Chiveroand Lake Manyame thus provided optimum conditions forproliferation of the water hyacinth weed Results from thepresent study support the concept that overgrowth of waterhyacinth in fresh water bodies reduces the amount of oxygendissolved in water The amount of dissolved oxygen is afactor which also interacts with other factors such as fish sizestocking density and fish behaviour to affect fish feeding [34]Dissolved oxygen is a major factor affecting fish growth andsurvival in the tropics together with the ability to tolerateearly morning low levels of dissolved oxygen The abilityof the fish to recover quickly from the physiological stress


created by low dissolved oxygen may also improve growthrate by extending feeding duration In previous studies [35]an oxygen concentration of 1024plusmn125mgLwas found to besufficient for health and performance of teleost fish whereasenvironmental hypoxia (703plusmn229mgL) reduced the abilityof fish to sustain metabolic processes In consonance withthese observations the dry matter protein and ash contentobtained in the present study were highest for fish from LakeKariba which happened to have the optimum concentrationof dissolved oxygen On the contrary environmental hypoxiain Lake Manyame may have contributed to levels of drymatter protein and ash being lowest in fish from this sourceBesides reducing availability of oxygen to fish proliferation ofwater hyacinth may directly reduce the dietary componentsavailable to fish by intercepting light and inhibiting growth ofphytoplankton

In addition to low levels of pollutants the large sizeof Lake Kariba relative to the other two lakes could haveimpacted positively the dry matter protein and ash contentof fish from that source by reducing stocking density andcompetition for food Tilapias have a preference for shallowwaters during feeding [36] therefore they tend to feed onfood items at the periphery of water bodies The largesurface of Lake Kariba provides expansive shorelines that aremore than adequate for the feeding character of Oreochromisniloticus

Lake Chivero had the highest density of water hyacinthof all three lakes The weed is concentrated in shallowwater along the shores because of inherent requirements forleaves to float on the water surface Oreochromis niloticusis known to feed on the remains of water hyacinth [37]As fish from Lake Chivero had the highest fat content of317 this might be an indicator that the principal food ofOreochromis niloticus from this source was water hyacinthAlthough plants are efficiently digested in fish that feed onmacrophytes the inherently low protein levels (761 of freshweight) in water hyacinth [38] mean that for the fish tomeet their protein requirements feed intake has to increaseIronically this would result in an energy surplus which isreflected as a high fat content in the fish Consumptionof water hyacinth as the major dietary component mayalso explain the higher levels of magnesium in fish fromLake Chivero compared to the other sources since the weedhas been shown to contain very high levels of magnesiumaveraging 02ndash03 of the dry matter [39] Proliferation ofwater hyacinth in Lake Chivero appears to be driven bythe significantly higher levels of phosphate and nitrates incomparison to the other two sources The high phosphorusand nitrate concentrations in Lake Chivero harvest watercan be attributed to the dumping of industrial waste fromthe fertilizer industry and inflow of fertilizer from streambank cultivation in addition to influx of sewage effluentA high concentration of phosphorous in the harvest watercould have resulted in the high phosphorus content of fishfrom Lake Chivero relative to fish from Lakes Kariba andManyame as shown in Table 2 This could be due to directabsorption of phosphate from ingested water or feedingon water hyacinth that has accumulated phosphorous fromthe ambient water As creatine phosphate phosphorous is

an important mineral element in muscle energy metabolismbut can become harmful when the concentration in fishtissues exceeds the metabolic demands [40]

5 Conclusion

The present analysis has broadened our knowledge on thenutritional value ofOreochromis niloticusunder different eco-logical conditions In particular the effect of pollutants fromsewer and industrial effluent on quality of water and chemicalcomposition of fish meat has been clearly demonstrated Inaddition depletion of oxygen content of water by overgrowthof water hyacinth weed and concomitant changes in carcassdry matter protein fat and mineral content have beenenunciatedThe present study could assist in determining thesuitability of different ecosystems to production and safety offish meat Differences in chemical composition of fish couldalso influence postharvest processing and storage techniquesWith the increase in demand for fish to fill in the gaps due tothe high cost of other meats this information is also useful indeveloping nutrient-balanced cost-effective diets for humannutrition as well as suitable feeds for cultured fish

Additional Points

Practical Applications The present analysis has broadenedour knowledge on the nutritional quality of Oreochromisniloticus under different ecological conditions Effects ofpollutants from sewer and industrial effluent on quality ofwater and chemical composition of fish meat have beendemonstrated Also depletion of oxygen content of water byovergrowth of water hyacinth and concomitant changes incarcass quality have been enunciated These findings couldassist in determining the effect of different ecosystems onproduction and nutritional value of fish meat

Competing Interests

The authors declare no conflict of interests regarding thepublication this paper

Acknowledgments

The authors wish to extent sincere thanks to Mr S Chikambiand Mr G Ashley for allowing them to do chemical analysisin the animal science and biological sciences laboratoriesSincere gratitude also goes to Mr V E Imbayarwo-Chikosifor assistance with the data analysis and Dr Halimani for hissupport

References

[1] V Venugopal ldquoBiosensors in fish production and qualitycontrolrdquo Biosensors and Bioelectronics vol 17 no 3 pp 147ndash1572002

[2] C William and C Dennis Food Microbiology McGraw-HillBook Company Singapore 4th edition 1988


[3] S P Aubourg and IMedina ldquoInfluence of storage time and tem-perature on lipid deterioration during cod (Gadus morhua) andhaddock (Melanogrammus aeglefinus) frozen storagerdquo Journalof the Science of Food and Agriculture vol 79 no 13 pp 1943ndash1948 1999

[4] T Zmijewski R Kujawa B Jankowska A Kwiatkowska andAMamcarz ldquoSlaughter yield proximate fatty acid compositionand sensory properties of rapfen (Aspius aspius L) with tissueof bream (Abramis brama L) and pike (Esox lucius L)rdquo Journalof Food Composition and Analysis vol 19 no 2-3 pp 176ndash1812006

[5] A E Andrew Fish Processing Technology University of IlorinPress Ilorin Nigeria 2001

[6] S T Arannilewa S O Salawu A A Sorungbe and B B Ola-Salawu ldquoEffect of frozen period on the chemical microbio-logical and sensory quality of frozen tilapia fish (Sarotherodungaliaenus)rdquo African Journal of Biotechnology vol 4 no 8 pp852ndash855 2005

[7] D Mozaffarian R N Lemaitre L H Kuller G L Burke R PTracy andD S Siscovick ldquoCardiac benefits of fish consumptionmay depend on the type of fish meal consumedrdquo Circulationvol 107 no 10 pp 1372ndash1377 2003

[8] J A Foran D H Good D O Carpenter M C Hamilton B AKnuth and S J Schwager ldquoQuantitative analysis of the benefitsand risks of consuming farmed and wild salmonrdquo Journal ofNutrition vol 135 no 11 pp 2639ndash2643 2005

[9] R G Ackman ldquoNutritional composition of fats in sea foodsrdquoProgress in Food and Nutrition Science vol 13 pp 161ndash289 1989

[10] H H Huss Fresh Fish Quality and Quality Changes FAOFisheries no 29 FAO Rome Italy 1988

[11] J J Waterman Composition and Quality of Fish A DictionaryTorry Research Station Edinburgh UK 2000

[12] S Clement and R T Lovell ldquoComparison of processing yieldand nutrient composition of cultured Nile tilapia (Oreochromisniloticus) and channel catfish (Ictalurus punctatus)rdquo Aquacul-ture vol 119 no 2-3 pp 299ndash310 1994

[13] T Zenebe G Ahlgren I-B Gustafsson and M Boberg ldquoFattyacid and lipid content of Oreochromis niloticus L in Ethiopianlakes-dietary effects of phytoplanktonrdquo Ecology of FreshwaterFish vol 7 no 3 pp 146ndash158 1998

[14] M R Ndebele ldquoPrimary production and other limnologicalaspects of Cleveland dam Harare Zimbabwerdquo Lakes amp Reser-voirs Research amp Management vol 14 no 2 pp 151ndash161 2009

[15] J Batram and J BAlanceWater Quality Monitoring A PracticalGuide to the Design and Implementation of Fresh Water QualityAnalysis Studies andMonitoring Programs Spon Press LondonUK 2001

[16] Association of Official Analytical Chemists Official Methods ofAnalysis Association of Official Analytical Chemists Washing-ton DC USA 17th edition 2000

[17] T Suzuki ldquoWhat is frozen minced meatrdquo in Fish and KrillProtein Processing Technology Applied Science London UK1981

[18] P Vlieg and T Murray ldquoProximate composition of albacoretuna Thunnus alalunga from the temperate South Pacific andTasman Seardquo New Zealand Journal of Marine and FreshwaterResearch vol 22 no 4 pp 491ndash496 1988

[19] M M Gaber ldquoGrowth of Nile tilapia fingerling (Oreochromisniloticus) fed diets containing different levels of clove oilrdquoEgyptian Journal of Aquatic Biology and Fisheries vol 4 pp 1ndash18 2000

[20] J E Kinsella ldquoFish and seafoods nutritional implications andquality issuesrdquo Food Technology vol 42 no 5 pp 146ndash150 1988

[21] Agricultural Research Service (ARS) USDA Nutrient dataRelease 22 2009 httpwwwnalusdagovfnicfood-comp

[22] M I Yeannes and M E Almandos ldquoEstimation of fish proxi-mate composition starting from water contentrdquo Journal of FoodComposition and Analysis vol 16 no 1 pp 81ndash92 2003

[23] O O Fawole M A Ogundrian T A Ayandiran and O FOlagunju ldquoMineral composition in some selected fresh waterfishes in Nigeriardquo Journal of Food Safety vol 9 pp 52ndash55 2007

[24] E A Khallaf and A A Alne-na-ei ldquoFeeding ecology ofOreochromis niloticus (Linnaeus) amp Tilapia Zillii (Gervias) in aNile canalrdquo Hydrobiologia vol 146 no 1 pp 57ndash62 1987

[25] M Njiru J B Okeyo-Owuor M Muchiri and I G CowxldquoShifts in the food of Nile tilapia Oreochromis niloticus (L) inLake Victoria Kenyardquo African Journal of Ecology vol 42 no 3pp 163ndash170 2004

[26] F A R Elhigzi S A Haider and P Larsson ldquoInteractionsbetween Nile tilapia (Oreochromis niloticus) and cladocerans inponds (Khartoum Sudan)rdquoHydrobiologia vol 307 no 1ndash3 pp263ndash272 1995

[27] A K Alams Chemistry and Microbiology of Fish and FishProcessing Department of Biochemistry Norwegian Instituteof Technology University of Trondheim Trondheim Norway1981

[28] J A Nettleton and J Exler ldquoNutrients in wild and farmed fishand shellfishrdquo Journal of Food Science vol 57 no 2 pp 257ndash2601992

[29] R George and R Bhopal ldquoFat composition of free living andfarmed sea species implications for humandiet and sea farmingtechniquesrdquo British Food Journal vol 97 no 8 pp 19ndash22 1995

[30] K D Shearer ldquoFactors affecting the proximate composition ofcultured fishes with emphasis on salmonidsrdquo Aquaculture vol119 no 1 pp 63ndash88 1994

[31] P C Morris ldquoThe effects of nutrition ion the composition offarmed fishrdquo in Farmed Fish Quality S C Kestin and P DWarris Eds Fishing New Books London UK 2001

[32] J R Wilson M Rees N Holst M B Thomas and GHill ldquoWater hyacinth population dynamicsrdquo in Biological andIntegrated Control of Water Hyacinth Eichhornia crassipes MH Julien M P Hill T D Centre and D Jianqing Eds vol 102of ACIAR Proceedings pp 96ndash104 2001

[33] D Little and J Muir A Guide to Integrated Warm WaterAquaculture Institute of Aquaculture Publications Universityof Stirling Stirling Scotland 1987

[34] D Houlihan T Boujard and L Jobling Food Intake in FishBlackwell Science Oxford UK 2001

[35] N D Martins W A Colvara F T Rantin and A LKalinin ldquoMicrocystin-LR how it affects the cardio-respiratoryresponses to hypoxia in Nile tilapia Oreochromis niloticusrdquoChemosphere vol 84 no 1 pp 154ndash159 2011

[36] D J Macintosh and S S De Silva ldquoThe influence of stockingdensity and food ration on fry survival and growth in Ore-ochromis mossambicus and O niloticus female timesO aureusmalehybrids reared in a closed circulated systemrdquo Aquaculture vol41 no 4 pp 345ndash358 1984

[37] N J Jihulya ldquoDiet and feeding ecology of Nile tilapia Ore-ochromis niloticus and Nile perch Lates niloticus in protectedand unprotected areas of Lake Victoria Tanzaniardquo InternationalJournal of Scientific amp Technology Research vol 3 pp 280ndash2862014


[38] F COkoye F Daddy and BD Ilesanmi ldquoThenutritive value ofwater hyacinth (Eichhornia crassipes) and its utilization in fishfeedrdquo in Proceedings of the International Conference on WaterHyacinth pp 65ndash70 New Bussa Nigeria December 2000

[39] B Wolverton and R C Macdonald ldquoDonrsquot waste waterweedsrdquoNew Scientist vol 72 pp 318ndash320 1976

[40] C Hogstrand and C M Wood ldquoThe physiology of zinc inteleost fish SEB seminar series-Aquatic Toxicologyrdquo in SEBSeminar Series-aquatic Toxicology EW Taylor andMMurphyEds vol 157 Cambridge University Press Cambridge UK1996

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Enzyme Research



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acid composition data are needed by food scientists andnutritionists in dietary formulation food processing andproduct development [9]The study of chemical compositionof fish is important since it influences keeping quality andtechnological characteristics of the fish [10] Measurementof proximate profiles such as protein lipids and moisturecontent is often necessary to ensure that they meet therequirements of food regulations and commercial specifica-tions [11] They also influence postharvest processing and theshelf-life of the fish [12]

The nutritional composition of freshwater fish was foundto differ between geographical localities [13] The changingbiological and environmental conditions are a useful tool tothe ecologist Ecologists require information on meat com-position to help create or maintain dam water atmosphereconducive for rearing a quality fish meat carcass So farthere has been research on other effects on fish but notmuch research has been done on the nutritional quality ofthe fish living in different ecosystems The present studyaimed to investigate the impact of different water sourceson the quality of Oreochromis niloticus (Nile tilapia) fromthree different fresh water sources Oreochromis niloticusis a popular fish and in Zimbabwe exists in abundancein Lake Kariba Lake Chivero and Lake Manyame Thecatchment areas of the water sources are different LakeChiverorsquos catchment introduces industrial effluent and rawsewage waste into the lake from large urban centres nearbyLake Manyamersquos catchment area introduces 10 million litresof raw sewage into the lake from a neighbouring town everymonth The catchment area of Lake Kariba is relatively freefrom waste and pollution The quality of water is consideredthe main factor in fish quality and also affects reproductionof fish In addition continued deposition of effluent into LakeChivero has abetted the spread of water hyacinth (Eichhorniacrassipes) which thrives under constant supply of nitrates andphosphates in effluent from fertilizer industries Due to thespread of the water hyacinth the water in Lake Chivero tendsto be highly deoxygenated compared to LakeManyamewherethe weed is less prevalent The water in Lake Kariba tends tobe highly oxygenated as the water hyacinth is scant and onlypresent in shallow water

2 Material and Methods

21 Description of Study Site The fish used in this study weresourced from three different ecosystems The description ofthe three water bodies is shown in Table 1

Figure 1 shows the schematic catchment areas for LakeManyame and Lake Chivero The catchment for Lake Karibastraddles a wide area within southern Africa and parts of eastAfrica

22 Collection of Water and Fish Samples Water and fishsamples were collected on the same day A total of 30 samplesof fish were collected comprising ten fish from each lakecaught using the seine netting and gill netting method Thefish were placed in ice soon after the catch to keep them fresh

Table 1 Description of Lake Chivero Lake Kariba and LakeManyame

Lake Surfacesize Climaterainfall Catchment

area

Kariba 5 580 km2 Hot temperaturesthroughout the year 1 352 000 km2

Chivero 2630 km2

NovemberndashMarchhotrainy MayndashAugust

cold and drySeptember-October hot

and dry

2 300 km2

Manyame 81 km2 Similar to Lake Chivero Same as LakeChivero

Water samples were collected with a Ruttner samplermounted to a speed boat using the integrated surface downprofile method to obtain a representative water sample [14]The water was collected into duplicate sterile sample bottleschilled in ice and transported to the laboratory for analysisBoth the fish and water samples were sent to the Departmentof Animal Science and the Department of Biological SciencesLaboratories at the University of Zimbabwe for analysis

23 Preparation and Analysis of Water Samples A portionof the water sample was vacuum pumped to pass througha Millipore glass fibre prefilter (GFP) for the analysis ofdissolved components The water was analysed for dissolvedoxygen phosphates nitrates and pHusing standardmethodsfor fresh water analysis as described previously [15]

24 Laboratory Analysis of Fish Samples Fish samples weresubjected to proximate analysis as described by the Associa-tion of Official Analytical Chemists (AOAC) [16]

241 Fish Sample Preparation Samples for fish analysiswere taken from the left side of each fish Samples werehomogenised by passing them twice through a mincerwith 4mm holes and mixed thoroughly Uniformity of thehomogenate was ensured by further mixing with a domesticfood processor The resultant homogenate was packed intoseveral small convenient sterile containers and stored at 0∘Cprior to laboratory analysis

242 Protein Analysis This was determined using the Kjel-dahl process as described by AOAC To 2 g of appropriatelyhomogenised fish sample weighed into a Kjeldahl flask 10 gof catalyst 25mL of concentrated H2SO4 and three glassbeads were added The contents were then digested with amixture of powdered potassium sulphate copper sulphateand selenium mixed in the ratio of 948 5 02 until beingclear Contents were cooled and diluted and 100mL of 40sodium hydroxide was added Exactly 50mL of 4 boricacid was poured into a separate conical flask and connectedto the distillation unit The mixture was distilled and thedistillate was collected into the boric acid containing 3 dropsof indicator until the volume was above 150mL Ammoniawas converted to ammonium metaborate and titrated with


0 10 20

(km)

Scale

North

30∘45998400E

30∘45998400E

18∘00

998400S18∘00

998400S

31∘00998400E

31∘00998400E



Protein



times 100

(1)




Fat



times 100

(2)







PhosphatesmgL

NitratesmgL pH








119884119894119895 = 120583 + 119879119894 + 119890119894119895 (5)


3 Results






4 Discussion





Ash

Fat

Protein pH

Kariba 2470a (0725) 330a (0304) 174a (0335) 1712a (0503) 617a (0111)

Manyame 1918b (0725) 176b (0304) 173a (0335) 1386b (0503) 606a (0111)

Chivero 2248a (0725) 227c (0304) 317b (0335) 1645a (0503) 658b (0111)






se 034 4769 17181 10758 9040 1151 054 0143 0097











5 Conclusion


Additional Points


Competing Interests


Acknowledgments


References


















































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


0 10 20

(km)

Scale

North

30∘45998400E

30∘45998400E

18∘00

998400S18∘00

998400S

31∘00998400E

31∘00998400E



Protein



times 100

(1)




Fat



times 100

(2)







PhosphatesmgL

NitratesmgL pH








119884119894119895 = 120583 + 119879119894 + 119890119894119895 (5)


3 Results






4 Discussion





Ash

Fat

Protein pH

Kariba 2470a (0725) 330a (0304) 174a (0335) 1712a (0503) 617a (0111)

Manyame 1918b (0725) 176b (0304) 173a (0335) 1386b (0503) 606a (0111)

Chivero 2248a (0725) 227c (0304) 317b (0335) 1645a (0503) 658b (0111)






se 034 4769 17181 10758 9040 1151 054 0143 0097











5 Conclusion


Additional Points


Competing Interests


Acknowledgments


References


















































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




PhosphatesmgL

NitratesmgL pH








119884119894119895 = 120583 + 119879119894 + 119890119894119895 (5)


3 Results






4 Discussion





Ash

Fat

Protein pH

Kariba 2470a (0725) 330a (0304) 174a (0335) 1712a (0503) 617a (0111)

Manyame 1918b (0725) 176b (0304) 173a (0335) 1386b (0503) 606a (0111)

Chivero 2248a (0725) 227c (0304) 317b (0335) 1645a (0503) 658b (0111)






se 034 4769 17181 10758 9040 1151 054 0143 0097











5 Conclusion


Additional Points


Competing Interests


Acknowledgments


References


















































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Ash

Fat

Protein pH

Kariba 2470a (0725) 330a (0304) 174a (0335) 1712a (0503) 617a (0111)

Manyame 1918b (0725) 176b (0304) 173a (0335) 1386b (0503) 606a (0111)

Chivero 2248a (0725) 227c (0304) 317b (0335) 1645a (0503) 658b (0111)






se 034 4769 17181 10758 9040 1151 054 0143 0097











5 Conclusion


Additional Points


Competing Interests


Acknowledgments


References


















































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology






5 Conclusion


Additional Points


Competing Interests


Acknowledgments


References


















































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology
















































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology












Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Comparative Analysis of Nutritional Value of Oreochromis ...

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