Optimization of Enzymatic Hydrolysis Process of Antarctic Krill and Cryoprotective Effect of Enzymatic Hydrolysates on Oyster Meat

In order to develop a safe and efficient non-phosphorus antifreeze agent,enzymatic hydrolysates of Antarctic krill were prepared to evaluate their cryoprotective effects,providing basic data for the development of new antifreeze agents.The alkaline protease was screened from the four proteases as experimental enzymes,and the enzymatic hydrolysis process was optimized by single factor experiment and orthogonal experiment. The freezing protection of oyster meat by enzymatic hydrolysates of Antarctic krill was studied with the indexes of the water loss rate,salt-soluble protein content,total sulfhydryl group content and Ca²⁺-ATPase activity.The results showed that the optimum conditions for enzymatic hydrolysis of Antarctic krill by alkaline protease were as follows:Temperature 55℃,pH8.5,enzyme dosage 2.6%,enzymatic hydrolysis time 5 h. Under these conditions,the relative molecular weight of enzymatic hydrolysates of Antarctic krill mainly distributed in the range of 100~5500 Da,accounting for 79.69% of the total enzymatic hydrolysates. The enzymatic hydrolysate of Antarctic krill could inhibit the loss of water after freezing storage,retard the decrease of salt-soluble protein content,Ca²⁺-ATPase activity and total sulfhydryl content,and its effect was better than that of phosphorus-containing antifreeze agent.Therefore,the enzymatic hydrolysate of Antarctic krill had freezing protection activity,which could be further separated and identified.