冻藏对牦牛肉蛋白质、脂质氧化和保水性的影响

Impact of Frozen Storage on Protein,Lipid Oxidation and Water Holding Capacity of Yak Meat

通过测定蛋白质氧化产物（α-氨基己二酸半醛、γ-谷氨酸半醛、α-氨基己二酸、希夫碱）以及脂质氧化产物（硫代巴比妥酸、己醛）的含量,研究不同部位牦牛肉（腰肌、股四头肌、背最长肌）在冷冻贮藏期间（-18℃,0-140 d）蛋白质、脂质氧化规律及其对保水性的影响。结果表明：血红素铁和超氧化物歧化酶在背最长肌冻藏阶段的脂质氧化进程中发挥着重要作用,较低的血红素铁含量以及较高的超氧化物歧化酶是背最长肌脂质氧化程度较低的主要原因。冻藏显著影响腰肌和股四头肌蛋白质的氧化,血红素铁与超氧化物歧化酶、过氧化氢酶共同调控氧化反应的发生：冻藏140 d后,血红素铁的促氧化作用使腰肌和股四头肌中的α-氨基己二酸半醛、γ-谷氨酸半醛含量均显著增加（P〈0.05）,尽管腰肌中的血红素铁显著高于股四头肌（P〈0.05）,但腰肌中相对较高的超氧化物歧化酶和过氧化氢酶使腰肌与股四头肌的α-氨基己二酸半醛、γ-谷氨酸半醛含量并无显著性差异;血红素铁含量更高的腰肌容易使其产生更多的α-氨基己二酸,但腰肌中相对较高的超氧化物歧化酶与过氧化氢酶协同作用使腰肌中的α-氨基己二酸含量极显著低于股四头肌（P〈0.05）。此外,冻藏引起的蛋白质羰基化反应显著影响牦牛肉的保水性,抗氧化酶活力最低、血红素铁含量相对较高的股四头肌保水性最差,其解冻汁液流失率是背最长肌的3.55倍。

The aim of this paper was to investigate the changes of protein,lipid oxidation and its impact on water holding capacity of Psoas major,Quadriceps femoris and Longissimus dorsi from yak during 140 d of frozen storage（- 18℃）. Samples were analyzed at sampling times upon thawing（ 0,28,56,84 and140 d） for lipid（ TBARS,hexanal） and protein oxidation products（ α-aminoadipic and γ-glutamic semialdehydes,α-aminoadipic acid,Schiff bases）. During the frozen storage,heme-iron and superoxide dismutase played an important role in the lipid oxidation process of Longissimus dorsi. Owing to a lower content of heme-iron and a relatively higher content of superoxide dismutase,Longissimus dorsi had a lower content of TBARS and hexanal. Frozen storage significantly influenced the oxidative stability of proteins in Psoas major and Quadriceps femoris. The protein oxidation process of PM and QF was co-regulated by heme-iron,superoxide dismutase and catalase. Because of the promoting oxidation ofheme-iron,the content of α-aminoadipic and γ-glutamic semialdehydes were also significantly improved.However,the content of heme-iron in Psoas major was significantly higher than Quadriceps femoris,the content of α-aminoadipic and γ-glutamic semialdehydes in Psoas major and Quadriceps femoris had no significant differences due to the higher content of superoxide dismutase and catalase. The content ofα-aminoadipic acid was relatively higher because of the higher content of heme-iron in Psoas major,but the content of α-aminoadipic acid in Psoas major was significantly lower than Quadriceps femoris（ P 0. 05）. Furthermore,the water holding capacity of yak meat was significantly affected by protein carbonylation reaction during the frozen storage. Owing to the lowest antioxidant enzyme activity and the highest heme-iron,the water holding capacity of Quadriceps femoris was the worst in three kinds of yak meat. The purge of Quadriceps femoris was higher than Longissimus dorsi for 3. 55 times.