| In this paper,grass carp meat protein was hydrolyzed and glycosylated to obtaining a kind of anti-oxidation sugar antifreeze.Meanwhile its antioxidant performance was evaluated,as well as the evaluation of improving the stability of frozen grass carp surimi.1.In order to develop a compound enzyme for the hydrolysis of grass carp meat,the crude protein content of grass carp(1200±200 g)was measured as 18.65±0.46%(wet weight),in which the ratio of water-soluble protein content to salt soluble protein content to insoluble protein content was 30.58%:59.70%:9.72%,that is to say,the proportion of compound enzyme for the hydrolysis of grass carp meat protein was about 3:6:1.Based on the DPPH clearance,five kinds of proteases from different sources were selected to hydrolyze the three kinds of proteins with different solubility in the extracted grass carp meat.On the basis of selecting the better hydrolytic enzymes corresponding to water-soluble protein,salt soluble protein and insoluble protein,different complex enzyme combinations were designed to further hydrolyze the grass carp meat protein and finally determine the fish protein water The optimal combination of the hydrolytic enzymes and the ratio of the activity of each enzyme were:alkaline protease:flavor protease:trypsin=3:6:1.Furthermore,the optimal conditions of enzymatic hydrolysis of grass carp meat protein complex enzyme were determined by single factor and response surface method with DPPH clearance as the index:the time of enzymatic hydrolysis was 4 h,the p H of enzymatic hydrolysis was 7.5,and the total amount of enzyme added was 800 U/g The DPPH clearance of the hydrolysate was 40.24±2.74%when it was 3 mg/m L.2.The optimal glycosylation conditions of enzymatic hydrolysates were determined by single factor and response surface method with DPPH clearance as index:the reaction time of glycosylation was 2 h,the amount of TGase enzyme was 900 U/g,the ratio of amino sugar to protein content of enzymatic hydrolysates was 9:1(W/W).When the glycosylation of enzymatic hydrolysates of grass carp meat was 3 mg/m L,the scavenging rate of DPPH radical was 68.05±1.67%on that condition.The grafting degree is 97.10±0.97%,which shows that the glycosylation reaction of the hydrolysate is complete and the glycosylation product has high purity.3.By comparing the scavenging rate,reducing power and ferrous chelation of V_C,enzymatic hydrolysate and their glycosylates,it was found that the scavenging rate of DPPH from high to low was glycosylate>V_C>enzymatic hydrolysate in the range of 1-5mg/m L.The reduction power of the three groups was in the test range of 1-10 mg/m L,and V_C>glycosylation>enzymolysis was maintained all the time,the ferrous chelation rate was in the range of 1-2 mg/m L,glycosylation>enzymolysis,and the ferrous chelation rate of the two groups was basically similar after 3 mg/m L,but the activity of V_C group was not detected.The above results showed that the hydrolysates showed good antioxidant capacity,and TGase glycosylation could significantly improve their antioxidant properties at a certain concentration.4.4%(W/W)Commercial antifreeze,0.1%(W/W)Vc,0.3%(W/W)grass carp enzyme hydrolysates and their glycosylates were added to grass carp surimi,and these surimi were placed at-20?for 8 weeks of frozen storage experiment.In addition,fish surimi without any additives was used as the control group.It was found that commercial antifreeze,V_C,enzymatic hydrolysate and their glycosylation compounds had protective effects on Surimi during the period of surimi frozen storage.The protective effect of enzymatic hydrolysate and its glycosylation compounds on Surimi during the period of surimi frozen storage was better than that of commercial antifreeze and V_C The protective effect is better than that of enzymatic hydrolysate. |
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