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Extraction Of Gelatin From The Skins And Bones Of Fresh Water Fish Species(A Case Study Of The Grass Carp Fish: Ctenopharyngodon Idella)

Posted on:2005-04-13Degree:MasterType:Thesis
Country:ChinaCandidate:David BaziwaneFull Text:PDF
GTID:2121360125960672Subject:Food Science
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The whole research study was aimed at investigating the feasibility of commercially processing gelatin from the skins and bones of fresh water fish species, using the grass carp fish as the pilot case study. Promising results would therefore widen the scope of raw materials from which gelatin can be obtained from. Motivation for this study was due to the desire to determine whether the abundant refuse emanating from the booming fresh fish filleting industry in East Africa could possibly be used to produce gelatin, solve the fish waste management problem, and consequently provide more jobs to the local populace.Type A gelatin was obtained from skins that had undergone an acidic immersion pretreatment (5%v/v H2SO4), while type B was extracted from partially de-mineralized bones (ossein) that had been subjected to an alkaline pretreatment (3% w/v NaOH). Type B had many gelatin species due to the varying durations of collagen hydrolysis undergone in each respective case.Comparative proximate analysis between the two types of gelatin was conducted and tests included; protein, amino acid composition, ash, mineral content, moisture, total sugars and fat content. Other tests included gel (bloom) strength determination, viscosity, coloration. The ability and effectiveness of bone gelatin to clarify fruit juices was also investigated by means of measuring the percentage transmittance in the juice under study. The effect of the incorporated gelatin on fruit juice acceptability was determined organoleptically using a test panel.Ossein pretreated for a 2weeks period exhibited the maximum % yield incase of bone gelatin, while the yield from intact skin was higher than that realized incase of de-scaled skin. Ash content in bone gelatin was rather too high, with the prominent elements being Na+ and Ca2+. The amino acid hydroxyproline, which is commonly associated with gelatin, was absent from all the gelatin types obtained. The protein purity and molecular weight values were significantly higher incase of type B gelatin. It was virtually impossible to determine the bloom strength of the obtained gelatin because of its failure to gel at the prescribed conditions.Ossein gelatin coloration was more appealing than that witnessed incase of skin gelatin. Bone gelatin exhibited the ability to clarify fruit juices over a period of time. It however imparted a fishy odor in the juice. This therefore implies that masking agents need to be used in liaison with this type of gelatin when processing food for human consumption.The study indicated that commercial processing of gelatin from fish bones would realize more profits than when if skins were used. The production process had 3 critical control points namely; at reception, purification and packaging. There is always a need to de-mineralize bones prior to pretreatment, and then later subject the obtained gelatin solution to an ion-exchange column if the ash content is to be lowered to acceptable levels. The use of a (3% w/v NaOH) solution was probably harsh and future research should endeavor to employ Ca(OH)2 instead. Studies on other fresh water species especially those from the tropics e.g. oreochromis niloticus (Nile tilapia) and lates niloticus (Nile perch) need to be done.
Keywords/Search Tags:Collagen, pretreatment, hydrolysis, type A and B gelatin, fish gelatin, fresh water fish species, grass carp (ctenopharyngodon idella), Nile tilapia, Nile perch, ossein, fish skin, gelatin safety, bovine spongiform encephalopathy, HACCP
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