鱼排酶解物对鳙鱼鱼糜冻藏过程中蛋白质变性的影响

Effects of enzymatic fish frame protein hydrolysate on denaturation of bighead carp surimi during frozen storage

利用木瓜蛋白酶、低温碱性酶、风味蛋白酶酶解红鱼(Sciaenops ocellatus)鱼排,分别获得木瓜蛋白酶酶解物(PPH)、低温碱性酶酶解物(LPH)和风味蛋白酶酶解物(FPH).对3种酶解物化学成分及氨基酸组成进行分析,结果显示,3种酶解物中总氨基酸含量都在70%以上,总氮含量为82.12%～84.61%.酶解物分别以5%(质量比)量加入鳙鱼(Aristichthys nobilis)鱼糜中,冻藏于-20℃.测定冻藏过程中肌原纤维蛋白质盐溶性和Ca2+-ATPase活性的变化,同时测量鱼糜凝胶弹性的变化,并对冻藏样品进行扫描电镜观察,抗冻效果同商业抗冻剂(4%蔗糖、4%山梨醇、0.3%多聚磷酸盐混合剂)进行比较.结果表明,各酶解物能够在一定程度上抑制鱼糜蛋白质的冷冻变性,延缓肌原纤维蛋白质盐溶性和Ca2+-ATPase活性的下降,鱼糜凝胶质量下降减少,其中木瓜蛋白酶酶解物具有最好的效果.

During the frozen-storage, fish muscle undergoes some ctetenoration m edible qualitles ainu functional properties for the processing. The deterioration of muscle protein is mainly attributed to the frozen denaturation of myofibrils. Recently, a potential use of enzymatic hydrolysates from various food materials, such as fishery products and residues from seafood processing as denaturation-suppressing materials, has been studied. It was well established that some amino acids strongly suppressed protein denaturation during frozen storage. Fish protein hydrolysate is a mixture of various peptides of various lengths. Hence, the suppressive effect of fish protein hydrolysate is highly expected. In this study, the effects of enzymatic protein hydrolysates on denaturation of bighead carp（Aristichthys nobilis ） surimi during frozen storage was studied. Three protein hydrolysates were prepared from red drum（ Sciaenops ocellatus ） frame by three enzymes, which were papain, low-temperature alkaline protease and flavourzyme. Their major components and amino acid composition were analyzed. Bighead carp surimi containing 5 % （w/w） protein hydrolysates was stored at - 20℃ Salt solubility and Ca^2 ＋ -ATPase activity of myofibrils were measured during frozen storage. Gel breaking force of surimi was measured concurrently. The structure of frozen samples were observed under scanning electron microscope（SEM）. Their effects were compared with commercial cryoprotectant （4 % sucrose,4 % sorbitol and 0.3 % polyphosphate）. The results showed that peptides were the major component of protein hydrolysates , which accounted for 82.12% -84.61%. Hydrophilic amino acids were the most abundant in the amino acid composition. Gly had the highest content, followed by Asp. Addition of protein hydrolysates to surimi suppressed the quick drop of the salt solubility and Ca^2 ＋ -ATPase activity of myofibrils. Two-step freeze denaturation pattern was converted into one-step denaturation pattern. After 60 days of frozen storage, the breaking force values of the gels without protein hydrolysates was only 47.6 %, while the values of gels containing protein hydrolysates were all over 66.8 %. The denaturation of surimi protein might be suppressed by the addition of the hydrolysates, especially the hydrolysate prepared by papain.