| China is a country with the abundant aquatic products, the output of aquatic products continues to keep a rapid growth. With the development of aquatic products industry, aquatic products processing has also developed sharply. Fish scale is one of the leftovers of aquatic products processing, which is rich in collagens. However, due to factors such as technical lack, most fish scales have not been exploited and directly discarded as waste, not only wasting greatly usable resources, but also bringing about certain degree pollution to the environment. If collagen can be extracted from the fish scales, not merely to utilize the resources of fish scales to its fullest extent, but also we can resolve the pollution problem arising from them, and the collagen safety problem which arose from foot and mouth disease and bovine spongiform encephalopathy.In this study, the procedure for acid method and enzymic method and the production of collagen by acid-enzyme compound extraction from the bighead carp scales were developed. The whole research was aiming at providing a feasible procedure for effective extraction of fish-scale collagen. The main research content and results were as follows:Oscillator was used to demineralize the fish scales. The optimum conditions of demineralization were as follows:hydrochloric acid concentration0.5mol/L, decalcification time57min and ratio of liquid to solid24mL/g, under which the decalcification rate reached87.02%.Four acid were used to extract collagen, just to find citric acid extract had the best organoleptic evaluation and higher extraction rate. The optimal conditions of acid extraction was using0.5mol/L citric acid extract36hours, with a ratio of sample to solution1:20. The optimal conditions of enzymic extraction method were found by orthogonal experiments as follows:enzyme concentration2%, ratio of sample to solution1:25, extraction time36h.In addition, effects of substrate concentration and extraction time on enzymic extraction were studied in detail. Based on Michaelis-menten equation, a kinetic model of Collagen-Papain was developed. The equation can ben expressed as-rs=4.9483E-3[S]0.9379×(0.94434+0.3692[S]-0.8483[S]2+0.3095[S]3)The structural characteristics of acid-extracted and enzyme-extracted collagen were preliminary identification by UV scanning spectrum, infrared spectrum and other methods. The result show that both acid-extracted and enzyme-extracted collagen had characteristic absorption peak of collagen, they are typical type I collagen. Meanwhile, the physicochemical property of acid-extracted and enzyme-extracted collagen, such as denaturation temperature, emulsifying property, hygroscopicity and foamability were studied systematically. The result show that denaturation temperature of acid-extracted and enzyme-extracted collagen were33.5"Cand29℃respectively. Acid-extracted collagen is better than enzyme-extracted collagen on emulsifying property, emulsion stability, hygroscopicity and moisture retention, but worse on foamability and foam stability.In addition, more attention was payed on the acid-enzymic compound extraction. The optimum processing technology of the compound extraction was as follows:acid extraction time24h; acid concentration0.7mol/L; ratio of material to acid1:15; enzyme concentration2%; enzyme extraction time48h; ratio of material to enzyme1:20. Using this optimization process, the yield of collagen was68.32%and the purity of collagen was93.27%. The partical function of collagen was measured and the results were compared with collagen peptides. The results showed that both collagen and collagen peptides had good hygroscopicity and moisture retention, but only collagen had unique construction of three-ply helix, fibrillogenesis ability and film forming ability. |
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