| In order to optimize the use of Atlantic cod frame, protein was extracted fromAtlantic cod frame and fish bones were obtained using Isoelectric solubilisation／precipitation (ISP) in this study. Fish bones were used for extracting gelatin. Study onextracting protein from Atlantic cod frame in ammonia system in order to avoidintroducing salts and affetcting the product quality and flavor. Conclusions were asfollows:1) The optimum parameters of extracting protein from Atlantic cod frame wereobtained by orthogonal experiment. The results showed that agitation, time, pH,temperature and solid-liquid ratio significantly affected the extraction process. Underthe condition of electric agitator (250r/min), the optimum extraction condition wasextraction time2.5h, pH13.5, extraction temperature40℃and solid-liquid ratio1:10(m/V). Under these conditions, the protein extraction rate reached47.68%. Analysisof hydroxyproline changes in the process of alkaline extraction, bone collagen didn’tdissolve out. The isoelectric point (pI) of the protein recovered from Atlantic codframe was4.5and the precipitation rate was70.26%. Protein powders were preparedby drying and the protein content was64.14%.2) The protein recovered from Atlantic cod frame contained18kinds of amino acid,in which8kinds of essential amino acids were43.97%. Amino acid score ofrecovered protein was higher than soybean protein and close to that of milk, whichindicated that recovered protein was one of high quality proteins. The mineralelements contents of Fe, Mg, Ca in recovered protein were0.47mg／100g、2.24mg／100g and16.62mg／100g respectively，which were lower than that of cod fillets.DHA and EPA, which were ω-3essential polyunsaturated fatty acids, accounted for30.25%in the fatty acids total content of recovered protein and was lower than that ofthe starting material.3) Protens and lipids in fish bones were effectively removed after Atlantic codframe was treated with alkali solution. Analyzed by scan electron micrography, fish bones contain no impurities, the structure became loose and collagen fibers appearedswelling. The above changes were beneficial to extract gelatin from fish bones. Theoptimum parameters of alkali method extraction for gelatin under the condition ofelectric agitator were obtained by orthogonal experiment. The optimum extractioncondition was alkali concentration4%, alkali treatment time7.5h, extractiontemperature70℃and extraction time4h. Under these conditions, the gelatinextraction rate was up to89.54%. The gelatin was analyzed by FT-IR and identified asa typical gelatin.4) Fish protein solubility in ammonia system was comparable with that in NaOHsystem. It showed that ammonia system could be used for extracting protein fromAtlantic cod frame. In ammonia system, the results indicated a better extraction effectwhen the extraction temperature was15℃and solid-liquid ratio was1:8. Comparedwith NaOH system, ammonia system could save20%water. Pressurized ammoniacould effectively regulate the pH of Atlantic cod frame homogenates. After releasedthe pressure of ammonia, the pH of homogenates remains largely unchanged, whichgreatly facilitates the subsequent experiment.To sum up, it realized that protein was extracted from Atlantic cod frame and fishbones were obtained using ISP. The recovered protein has high nutritional value andmay be useful in the development of human food and animal feeds. Fish bones wereclear from protens and lipids, so they could be used as an ideal raw material extractinggelatin. Extracting gelatin from bones using alkali method was conducted understirring conditions. It has such specialties as high extracting rate and short extractiontime. Fish protein solubility in ammonia system was comparable with that in NaOHsystem. In addition, ammonia system has a good water-saving effect and is easilycontrolled. These conclusions provide a theoretical basises of implementation of highvalue utilization of Atlantic cod frame in industrial production. |
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