Study On Enzymatic Hydrolysis Technology Of Silver Carp Viscera And Behavior Of Hydrolysate

Silver carp viscera is rich in protein and has the fine ratio of amino acids. If it can be make full use of, its processing cost will be decreased and the value of Silver carp will be increased accordingly. But Silver carp viscera contains much water and oil, which will lead to rapid decay, serious pollutions will come up without a timely treatment.In this study silver carp viscera was used as the materials, the process technology of silver carp viscera by endogenous protease and exogenous protease was studied. The nutritional characteristics, physicochemical and functional properties were also analyzed, with expectation to get a comprehensive acknowledge about the processability of silver carp viscera and lay a foundation for the efficient use of silver carp viscera.(1) The fundamental component and enzyme activity of endogenous protease of silver carp viscera in different seasons were measured. The viscera accounted for 11.99%-16.03% of the total weight. In four different reasons it was 12.54%, 16.03%, 12.63% and 11.99% respectively. The solid content in the viscera was 35.13%-37.22%, the protein content was 6.82%-7.04%, the fat content was 22.48%-25.99% and the ash content was 4.28%-6.01%. The total amount of amino acids was162.14mg/g, and essential amino acids was 77.18mg/g. The optimum pH and temperature of endogenous protease activity was 8.8-10.2 and 40-70℃respectively.(2) The condition of silver carp viscera hydrolyzed by endogenous protease, alkaline protease and compound enzyme of the former two enzymes were determined. The results showed that the hydrolysis condition have significant effect on the degree of hydrolysis and nitrogen recovery ratio. Hydrolysis degree and nitrogen recovery ratio of compound enzyme were much higher than that of endogenous protease and alkaline protease alone. The optimal hydrolysis condition were that silver carp viscera was mixed with water at the ratio of 1:3 and beating, alkaline protease of 2000 U/gprotein was added in at 55℃and pH 9.0, after 6h of hydrolysis, the degree of hydrolysis and nitrogen recovery ratio were 38.07% and 64.52% respectively.(3) The nutritional components and the molecular weight distribution of hydrolysis product were determined, in which the content of protein was 83.22%, the fat was 3.30%, the ash was 10.92% and the essential amino acids were up to 47.60% of the total amount of amino acids. The molecular weight of the hydrolysate was 100-3900Da by SephadexG-25 gel filtration chromatography.(4) Effect of hydrolysate concentration, pH, concentration of sodium chloride and sucrose on the functional properties of hydrolysate were studied. The index of soluble nitrogen in hydrolysate was over 95% at different pH values, pH values, concentration of sodium chloride and sucrose had significant effect on emulsifying property, foamability and viscosity of the hydrolysate. The emulsifying stability and ability, foamability and foam stability, viscosity increased with increase of hydrolysate concentration. The indexes above were lower at pH 6.0. The emulsifying ability, foamability weakened with the increase of sodium chloride concentration. The foam stability, viscosity increased with the increase of sucrose concentration.