The Research Of Making Use Of Tuna Meat By Enzymatic Hydrolysis And Modification

Tuna is famous for its high nutritional value, and its economic value is very high. Being one of the main fishing species, tuna is often used to make sashimi tuna, fish fillet, fish steck and many kinds of canned fish products. During this process, a lot of waste, about50%～70%of the total weigh will be left. The waste used to be processed into feed and has low economic value. As for this, this paper intends to use enzymatic hydrolysis and modification to improve its economic value, which will be a reference for the comprehensive utilization of tuna meat.In this research, five kinds of enzymes, protamex, neutral protease, trypsin, flavor protease, alkaline protease were used for the hydrolysis of tuna meat. Then the degree of hydrolysis, the recovery ratio of protein, the amino acid composition and molecular weight distribution were determined. The results showed that the effects of the five kinds of enzymes from high to low were protamex, trypsin, neutral protease, flavor protease and alkaline protease in turn, while the degree of hydro lysis was regarded as index. When we regarded the recovery ratio of protein as index, the effects of the five kinds of enzymes from high to low were protamex, trypsin, neutral protease, flavor protease and alkaline protease in turn. When the amino acid composition and molecular weight distribution were regarded as indexes, the effect of protamex was the highest, trypsin was the second, then neutral protease, flavor protease and alkaline protease. In addition, this research determined the moderate hydrolysis condition using the content of soluble protein as an index. Results showed that the hydrolysis condition was:trypsin as enzyme, ratio of material to water1:2, additive amount20000U/g, temperature50℃, pH8, time2.5h.Sodium alginate is a kind of carbohydrates extracted from brown algae such as seaweed or sargasso. Some research showed that mixed sodium alginate with the myofibril protein of fish can improve the solubility of myofibril protein. In this research we mixed the hydrolyzed tuna meat with sodium alginate in the ratio of1:1and incubated under the condition of temperature60℃, relative humidity65%for3hours. Then we determined the solubility, reducing power, emulsifying activity and stability. Results showed that the solubility, emulsifying activity and stability of the hydrolyzed tuna meat mixed with sodium alginate were higher than the unmixed.Konjac mannan is a kind of high molecular weight and nonionic polysaccharides. Research showed that, adding konjac mannan to the waste of fish can improve its gel properties. We used response surface design to optimize the condition of adding konjac mannan to tuna meat to improve its gel properties. Finally we determined the condition as follows:the content of konjac mannan1.5%, the incubation temperature32.3℃and incubation time184.6min.