Preparation Of Grass Carp Fish Scale Gelatin Hydrolysate And Study On Its Antifreeze Effect

China is a major producer and consumer of freshwater fish,and its total output ranks first in the world.Freshwater fisheries have played an important role in our national economy.With the continuous development of aquaculture technology,the output of freshwater fish is increasing year by year,and the freshwater fish processing industry is also booming.While meeting people's living needs,it also produces a large amount of by-products of freshwater fish in processing,which pollutes the environment and causes waste of resources.Therefore,the deep processing of freshwater fish by-products and high-value comprehensive utilization technology is the focus and hot spot of current research.In order to improve the high-value utilization of grass carp fish scales,this paper takes grass carp fish scales as the research object,uses protease to prepare fish scale gelatin hydrolysate,and uses physical and chemical analysis and spectroscopic analysis techniques to study the antioxidant activity of the hydrolysate and the antifreeze effect of grass carp,also include The effect on actomyosin,provide technical guidance for the application of grass carp fish scale gelatin hydrolysate as an antifreeze in food processing,and provide new methods and new ideas for the development of new antifreeze.The specific research results are as follows:(1)The grass carp fish scales are used as raw materials to prepare gelatin,and trypsin and flavor protease are used to enzymatically hydrolyze the gelatin to study the antioxidant effect of the two hydrolysates on fish meat.The results showed that the content of hydrophobic amino acids in the hydrolysate was 24.5%the content of peptides below 2000 Da in Trypsin hydrolysates(Ths)reached 65.21%,and the flavor protease hydrolysates(Fhs)is 38.92%.Ths has higher DPPH·,· OH,P2-· scavenging rate,while Fhs has the best low temperature protection activity of catalase.Both Ths and Fhs can reduce the TBARS value of fish meat during freezing and thawing,but Ths has a better effect.The DSC curve shows that Fhs can reduce the specific heat capacity and freezing point of the aqueous solution.(2)The effects of Ths and Fhs on the quality of grass carp fish meat during freeze-thaw were studied.It was shown that the content of salt-soluble protein in fish meat treated with Fhs after freeze-thaw 3 and 5 times was reduced by 13.94%and 49.42%,Significantly lower than 42.53%and 69.16%of the blank group(P<0.05).The pH of the fish meat showed an upward trend during the freeze-thaw process,but the pH of the fish meat treated with Ths and Fhs was lower than that of the blank group.The addition of hydrolysate resulted in a darker fish color.In addition,the water holding capacity of fish with Ths and Fhs increased significantly compared with the blank group(P<0.05),and the increase was slightly greater than that with commercial antifreeze.Ths and Fhs did not affect the change of TVB-N content in the freezing and thawing process of fish,neither of these hydrolysates could inhibit the degradation of protein by microorganisms.The texture speed of Ths and Fhs treated fish meat during freezing and thawing decreased significantly.This study shows that Ths and Fhs have a certain protective effect on grass carp fish meat in the process of freezing and thawing.(3)The effect of Ths and Fhs on the properties of actin in grass carp during freezing and thawing was studied.During freezing and thawing,the turbidity of the actin solution showed an upward trend,but Ths and Fhs could reduce the actin The degree of protein aggregation delays the rate of increase in turbidity.When the shear rate increased,the viscosity of the protein solution continued to decrease until the shear rate reached 10 s-1,but the viscosity of the component protein solution with Ths and Fhs added was significantly higher than that of the blank group.Ths and Fhs can significantly reduce the fluorescence intensity of the actin solution and reduce the degree of unfolding of the protein structure.The Ca2+-ATPase activity of actin has a downward trend,and the addition of Ths and Fhs can delay this process.The results of the active thiol content and surface hydrophobicity of the actin solution show that Ths and Fhs can reduce the damage of the actin structure in the process of freezing and thawing to a certain extent,thereby achieving protection.