肌肽联合超高压对黑鱼肉脂质氧化及肌原纤维蛋白的影响

为研究肌肽联合超高压（CUH）对黑鱼肉脂质氧化及肌原纤维蛋白（myofibrillar protein，MP）的影响，以新鲜宰后黑鱼肉为材料，比较分析CUH（肌肽浓度25 mmol/L，超高压压力300 MPa，保压时间900 s）处理对黑鱼肉在冷藏期间的脂质氧化、蛋白氧化、蛋白降解、蛋白结构等的影响。通过测定超高压后黑鱼中脂肪氧合酶活和CUH处理过鱼肉丙二醛（MDA）含量的变化来分析鱼肉脂质氧化情况；通过检测冷藏期间鱼肉蛋白羰基含量的变化表征鱼肉蛋白氧化程度；利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）、TCA-溶解肽和总蛋白酶活探究CUH处理对鱼肉蛋白降解的影响；为进一步了解鱼肉CUH对黑鱼肉及肌原纤维蛋白结构的影响，分别对冷藏期间黑鱼肉进行扫描电镜（SEM）和圆二色谱（CD）的跟踪测定。结果表明:超高压处理使鱼肉脂肪氧合酶活下降了64.46%，CUH处理过的鱼肉在冷藏期第9 d脂质氧化和蛋白氧化抑制率分别为51.25%和3.63%。超高压处理使鱼肉总蛋白酶活下降了25.75%，CUH处理显著降低了鱼肉冷藏期间肌原纤维蛋白的降解（P<0.05），第9 d蛋白降解抑制率为63.41%。CUH处理过的鱼肉在冷藏期间纤维完整且紧密，鱼肉体系中有新的氢键的形成，蛋白结构呈现有序化。综上所述，CUH处理能抑制黑鱼肉在冷藏期间的脂质氧化、蛋白氧化和蛋白降解，并维持鱼肉及肌原纤维蛋白结构，从而显著提高黑鱼肉的品质，为改善黑鱼肉贮藏品质提供理论依据。

Effects of Carnosine Combined with Ultra High Pressure on the Lipid Oxidation and Myofibrillary Protein of Snakehead Fish

The study aimed to investigate the effect of carnosine combined with ultra-high pressure(CUH)on the lipid oxidation and myofibrillar protein(MP)of snakehead fish meat during refrigerated storage.Studies on lipid and protein oxidation,protein degradation and protein structure were used to analyze the effect of CUH treatment(carnosine concentration 25 mmol/L,ultra-high pressure pressure 300 MPa,pressure holding time 900 s)on snakehead fish.The lipid oxidation of fish meat was analyzed by measuring the lipoxygenase activity and the change of MDA content in CUHtreated fish.The change in the carbonyl content of MP during refrigerated storage was used to characterize the degree of fish protein oxidation.SDS-PAGE,TCA-soluble peptides and total protease activity were used to determine the effect of CUH treatment on fish protein degradation.In order to further understand the effect of CUH treatment on the structure of snakehead fish meat and MP during refrigerated storage,SEM and CD tracking measurements were carried out on fish.The results showed that the lipoxygenase activity of fish meat treated with ultra-high pressure decreased by 64.46%.The inhibition rates of lipid oxidation and protein oxidation of fish treated with CUH were 51.25%and 3.63%on the 9th day of the refrigerated storage period,respectively.The total protease activity of fish after UHP treatment decreased by 25.75%.CUH treatment significantly reduced the degradation of MP during refrigerated storage(P<0.05).The protein degradation inhibition rate was 63.41%on the 9th day.The CUH-treated fish had complete and tight fibers during refrigerated storage.New hydrogen bonds were formed in the MP and the structure of proteins was more orderly arranged.In summary,CUH treatment could not only inhibit the lipid and protein oxidation and protein degradation of snakehead fish,but also maintain the structure of fish meat and MP.CUH treatment significantly improved the quality of snakehead fish and would provid a theoretical basis for improving the storage quality of black fish meat.