Antifreeze Mechanism Of Hydrolyzed Products Of Silver Carp In Frozen Surimi And Its Application

Silver carp,as one of the four major fish in China,has high nutritional value,but it has many intermuscular thorns and heavy smell of soil,so it is usually processed into surimi recombinant products,Protein and starch are usually added to the recombinant products of surimi,which can increase the gel strength of surimi products and reduce the cost of surimi products.In order to relieve freezing denaturation of surimi recombinant products,antifreeze is usually added to surimi.Commercial antifreeze has certain sweetness and does not conform to modem eating habits,so it is very necessary to seek new antifreeze.In this paper,Silver carp was used as raw material to investigate the addition of soybean protein isolate,cassava starch and transglutaminase by measuring water holding capacity,cooking loss and gel strength.Based on the addition of the hydrolyzed products to surimi,the gel strength and flavor substances of 6 freeze-thaw cycles were used as indexes to explore the best antifreeze agent.Finally,the antifreeze mechanism of the hydrolyzed products was studied.The specific results of the study are as follows:(1)Soybean protein isolate,cassava starch and transglutaminase were added to silver carp surimi.Through gel strength,water holding capacity and cooking loss,the addition of soybean protein isolate was 9%of surimi and cassava starch was 6%.Transglutaminase is 4 U/g protein.The water distribution,state and microstructure of the freeze-thaw cycle were analyzed between the added group and the unadded group.The results showed that the A23 of the added group decreased by 11%and the unadded group decreased by 25%after 6 times of freeze-thaw.The micro structure of the added group remained highly crosslinked after 6 freeze-thaw times,while that of the unadded group remained highly crosslinked after 3 times freeze-thaw.(2)On the basis of the optimum addition of excipients,the related characteristics of antifreeze to surimi during freeze-thaw cycle were studied.The results showed that with the increase of freeze-thaw times,the whiteness of all experimental groups decreased,and the whiteness of the blank group was higher than that of the enzyme hydrolyzed product group and the quotient resistance group.The gel strength of the blank group decreased by 31.8%,the quotient resistance group decreased by 17.0%,and the 2%hydrolyzed product group decreased by 11.2%.The sensor of electronic nose is mainly sensitive to sulfides and nitrogen oxides during freeze-thaw cycle,and is sensitive to aromatic components,organic sulfides and methane.2%hydrolyzed product group responds during freeze-thaw cycle.After 6 times of freeze-thaw,the A24 of 2%hydrolyzed products was 81.0%and 13.3%,80.3%and 18.0%of the blank group,and 80.2%and 15.4%of the commercial resistance group,respectively.after 6 times of freeze-thaw,the A24 was 81.0%and 13.3%,the blank group was 80.3%and 18.0%,and the quotient resistance group was 80.2%and 15.4%,respectively.(3)The effects of 2%hydrolyzed products on the related characteristics of surimi during freeze-thaw cycle were studied by comparing 2%hydrolyzed products with commercial antifreeze.The results showed that A23 increased with the decrease of freeze-thaw times during freeze-thaw.The A23 and A24 of 2%hydrolyzed product group were 93.47%and 3.98%,respectively,while those of commercial resistance group were 21.58%and 6.17,respectively.During 6 freeze-thaw cycles,the A23 of the same 2%hydrolyzed product group was higher than that of the quotient resistance group,and the A24 was lower than that of the quotient resistance group.The gel mesh of chimi gel in 2%hydrolyzed product group was freeze-thawed for 6 times.The pore structure appeared on the surface of commercial antifreeze,and the gel network structure was not obvious.Under the low temperature microscope,it was observed that after the sucrose solution was kept at 20 min,the small ice crystals were continuously merged together to increase the ice crystals,and the ice crystals in the hydrolyzed product group were smaller and less in number.When the sugar solution was kept for 20 min,the size of the ice crystals changed little.After separation and purification,the components with less than 3 kDa formed smaller and more uniform ice crystals than the other two components,and the morphology of ice crystals was more regular.