解冻方式对牦牛肉蛋白氧化、功能特性及新鲜度的影响

Effects of Thawing Methods on Protein Oxidation,Protein Functional Properties and Freshness of Yak Meat

以冻结牦牛肉背最长肌为试验对象,探究不同解冻方式对牦牛肉蛋白质氧化、功能特性及新鲜度的影响。结果表明,空气解冻方式牦牛肉肌原纤维蛋白(MP)总羰基含量最高,其质量摩尔浓度为9.80 nmol/mg,表面疏水性指数最高,为48.53μg,总巯基含量最低,其质量摩尔浓度为41.73 nmol/mg,Ca^(2+)-ATPase活性最低,为0.245 U/mg;空气解冻与其他解冻方式之间均存在显著差异(p <0.05),说明空气解冻后肌肉蛋白质氧化程度最严重,其他解冻方式导致的蛋白质氧化程度由轻到重顺序依次为冷藏解冻、静水解冻、微波解冻、室温解冻。空气解冻牦牛肉的全蛋白溶解度为109.28 mg/g、MP溶解度为69.16 mg/g、乳化活性指数为31.51 m^(2)/g,均显著低于其他解冻方式(p <0.05),说明空气解冻对肌肉蛋白质溶解和乳化能力最为不利。冷藏解冻牦牛肉脂质过氧化程度最低,微波解冻牦牛肉挥发性盐基氮(TVB-N)含量和菌落总数最低。同时,解冻牦牛肉蛋白质氧化和脂质氧化之间存在极显著相关性,蛋白溶解度与蛋白乳化能力之间也存在极显著相关性(p <0.01)。研究表明,空气解冻方式对牦牛肉品质最为不利,其次是室温解冻,而冷藏解冻、微波解冻和静水解冻可在不同层面有效延缓肌肉品质的下降过程,在一定程度上维持解冻肉的品质。

The frozen Longissimus dorsi(LD)of yak meat were taken as the experimental objects to investigate the effects of different thawing methods on the protein oxidation,functional properties and freshness of yak meat.The results showed that the myofibrillar protein carbonyl groups were the highest of 9.80 nmol/mg,surface hydrophobicity was the highest of 48.53μg and the total sulfhydryl groups were the lowest of 41.73 nmol/mg and Ca^( 2+)-ATPase activity was the lowest of 0.245 U/mg protein in the air thawing yak meat,which was significantly different from other thawing methods(p<0.05),indicating that the meat protein oxidation was the heaviest after air thawing.And the other thawing methods resulting in protein oxidation in descending order were refrigerated thawing,hydrostatic thawing,microwave thawing,and room temperature thawing.The protein solubility was 109.28 mg/g,MP solubility was 69.16 mg/g and EAI was 31.51 m 2/g in the air thawing yak meat,all of which were significantly lower than those of other thawing methods(p<0.05),indicating that air thawing was most unfavorable to meat proteolysis and emulsification.Meanwhile,the lipid peroxidation of refrigerated thawed yak meat was the lowest as well as the TVB-N of microwave thawed yak meat was the lowest.There was a significant correlation between protein oxidation and lipid oxidation in thawed yak meat,and also between protein solubility and emulsifying ability(p<0.01).These above results indicated that the air thawing was most detrimental to the quality of thawed yak meat,followed by thawing at room temperature.However,refrigerated thawing,microwave thawing and hydrostatic thawing respectively can delay the onset of meat quality decline process effectively in different levels,and can maintain the defrosted meat quality to some extent.The findings can provide data support and theory reference for illustrating the mechanism of different thawing methods on defrosted meat quality in the future.