Study On Comprehensive Utilization Of Silver Carp Residual Waste From Meat Separation For Surimi Processing

In china large freshwater fish, the aquaculture of silver carp is large. Becase of the silvercarp muscle has more thorns and poor flavor,the price of fresh silver carp is low, to someextent, restricted the market value of the silver carp. In recent years, with the development offreshwater surimi preparation technology, people try to processing fresh or frozen carp intosurimi, also obtained some success. However, in the meat separation for surimi processingwill produce about32%residual waste of the total weight of fresh fish, these waste includingresidual meat, skin, fish bones, ect al, with about16%of the protein content. So far, this typeof residual waste has not been well utilized, resulting in a waste of resources andenvironmental pollution pressures. To realize the comprehensive utilization of silver carpresidual waste from meat separation for surimi processing, in this study, the alkali-solubleprotein product and gelatin product were prepared by using silver carp residual waste frommeat separation for surimi processing as raw material.Firstly, the preparation process of alkali-soluble protein using the method of pH-shiftingwas studied. Mainly studied the composition of raw material, the effect of extracting pH、time、and temperature、ratio of material and buffer on the extraction rate of alkali-solubleprotein, and pH for precipitate of alkali-soluble protein was also investigated. Results showedthat silver carp residual waste from meat separation for surimi processing contains16%protein,60%of the protein is alkali-soluble protein. The optimal extraction conditions foralkali-soluble proteins were extracting at pH12.0, for15min, at5°C, using two-stageapproach to extract,at ratio of1:6(fish waste: buffer), at pH5.5for precipitate. The recoveryof alkali-soluble protein was about82%under this condition. Different storage conditions andstorage time of material had little difference on the yield of alkali-soluble protein.Secondly, the nutritional value of alkali-soluble protein product is evaluated, and itsfunction is also studied. Results show that the protein content of alkali-soluble protein productis higher, including about50%essential amino acid, the ratio of essential amino acid andnon-essential amino acid is about98%, it is a high-quality protein product. From the aminoacid score analysis, alkali-soluble protein product completely accord with adult nutritionalrequirements. From the perspective of baby amino acid requirements, the first and the secondrestrictive amino acid are tryptophan and histidine, and lysine score is higher; From the viewof chemical score, the first and the second restrictive amino acid are methionine andtryptophan. SDS-PAGE electrophoresis analysis showed that the molecular weightdistribution of alkali-soluble protein meets the typical characteristics of fish muscle proteinelectrophoresis patterns.Thirdly, using the alkali-insoluble fraction of silver carp residual waste from meatseparation for surimi processing as raw material, the preparation technology of gelatin wasstudied. Through single factor experiment investigated the factors of acid and alkali treatmentconditions, extraction temperature, extraction time on the influence of gelatin quality andextraction yield. On this basis, the process of gelatin extraction of silver carp residual waste from meat separation for surimi processing,the acid and alkali treatment conditions wereoptimized by orthogonal experiment. Optimized to get the best conditions were: the leachingmaterial liquid ratio (w/v) is1:3, NaOH concentration is0.3%(w/v), HCL concentration is0.4%, Acid and alkali processing3times, each time for30min, then extracted under neutralcondition, extraction temperature45℃, extraction time6h. Under the optimum technologicalconditions, the gelatin yield is about81%, the gel intensity is about680g, the gel viscosity isabout9.7mPa·S, bloom method is used to determine the gel strength is248g, in accord withnational A grade standard of edible gelatin. Gelatin liquid after ultrafiltration, concentratedunder vacuum condition and freeze-drying obtained gelatin product.Finally, part of the gelatin product’s physicochemical properties and film-formingproperties were studied. The results show that the amino acid composition of gelatin product,rich in glycine, alanine, proline, hydroxyproline, meet the characteristics of fish gelatin. Theisoelectric point of gelatin product is about8.3, index of surface hydrophobicity is2.985.According to the research results of the gelatin film, the best concentration of gelatin film is5%.