Fish Gelatin From Surimi Processing By-Products: Extraction And Characterization

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Date
2010-11
Authors
Bakar, Muhammad Khairulnizam Bin Abu
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Publisher
Universiti Sains Malaysia
Abstract
Fish gelatin was extracted from surimi processing by-products of four different fish species, namely slender shad (Elongata ilisha), sin croaker (Johnius dussumieri), ribbon fish (Trichiurus lepturus) and threadfin bream (Nemipterus japonicus). These by-products consisted of skins, bones and scales. In the initial study, highest yield of fish gelatin was obtained from slender shad fish by-products and this species was then selected for optimization of gelatin extraction condition study. Several factors that could influence the gelatin extraction process were optimized using response surface methodology (RSM) approach. The screening experiment using a 2-level full factorial design resulted in a first-order model equation indicated that three factors, i.e. citric acid concentration, extraction temperature and extraction time had significant effect on gelatin yield. This was followed with optimization experiment consisting of a 5-level central composite rotatable design (CCRD) with responses measured for gelatin yield, gel strength and viscosity. The suggested optimum conditions for gelatin extraction were using 0.14 M for the citric acid concentration, 63 ÂșC for the extraction temperature and 6 hrs for the extraction time. The predicted values for response gelatin yield, gel strength and viscosity under this optimum condition were 6.8 %, 163 g and 3.7 mPa.s, respectively. The actual experimental values obtained from verification experiment were gelatin yield, 6.6 %; gel strength, 161 g and viscosity, 3.4 mPa.s. Physicochemical, functional, rheological and thermal properties of extracted fish gelatin under optimum conditions were studied and compared with those of commercial fish, porcine and bovine gelatin preparations. The extracted fish gelatin was brownish yellow in color with contents: moisture, 8.7 %; protein, 86.3 %; ash, 2.2 % ash and pH value, 4.7. The clarity of extracted fish gelatin solution measured as percent transmittance was 80.7 %. The Fourier transform infrared (FTIR) spectra of extracted fish gelatin showed similar absorption band characteristics as the commercial gelatins.
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Keywords
Fish gelatin from surimi processing , extraction and characterization
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