高盐氧化体系对牦牛肉肌纤维蛋白理化特性及结构的影响  

Effect of High Salt Oxidation System on Physicochemical Properties and Structure of Yak Myofibrillar Proteins

作　　者：李璇 孙栋 胡婷 江华明[1] 郝刚[2] LI Xuan;SUN Dong;HU Ting;JIANG Huaming;HAO Gang(School of Food and Biotechnology,Sichuan Vocational and Technical College,Suining 629000,China;College of Food Science and Technology,Southwest Minzu University,Chengdu 610000,China)

机构地区：[1]四川职业技术学院食品与生物技术学院,四川遂宁629000 [2]西南民族大学食品科学与技术学院,四川成都610000

出　　处：《食品科学》2024年第15期49-58,共10页Food Science

基　　金：中央高校基本科研业务费专项(2021NYYXS36)。

摘　　要：在0.6 mol/L的NaCl浓度条件下分别构建pH 5.0和pH 8.0的Fenton氧化体系(H_(2)O_(2)浓度1、10、20、40、60 mmol/L),处理牦牛肉背最长肌1 h,研究蛋白氧化对牦牛肉理化特性及蛋白质结构的影响。结果表明,随着H_(2)O_(2)浓度的增加,牦牛肉蛋白羰基含量、表面疏水性、双酪氨酸含量增加,总巯基含量、活性巯基含量、蛋白质溶解度、色氨酸荧光强度下降。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析结果显示,蛋白氧化后肌球蛋白重链和肌动蛋白条带减少,且蛋白间存在二硫键等形式的共价交联,表现为肌肉离心损失率和蒸煮损失率的增加。通过低场核磁共振检测肌肉横向弛豫时间和扫描电镜观察肌肉微观结构可知,肌肉离心损失率和蒸煮损失率的增加是由于蛋白氧化使肌肉微观结构被破坏,不易结合水含量减少,自由水含量增加。对比发现pH 8.0时牦牛肉蛋白的离心损失率、蒸煮损失率、自由水含量以及肌肉微观结构的受损程度低于pH 5.0,可见同等氧化条件下,肌肉蛋白在靠近等电点时更易氧化损伤,持水性更低。In order to elucidate the effect of protein oxidation on physicochemical properties and protein structure of yak longissimus dorsi muscle,muscle samples were treated in a Fenton oxidation system(H_2O_(2) concentrations of 1,10,20,40 and 60 mmol/L) containing 0.6 mol/L NaCl at pH 5.0 or 8.0 for 1 h.The results showed that with the increase of H_2O_2concentration,the carbonyl content,surface hydrophobicity and dityrosine content of yak myofibrillar proteins increased,while the contents of total sulfhydryl and active sulfhydryl,solubility,and tryptophan fluorescence intensity decreased.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) analysis showed that the numbers of myosin heavy chain and actin bands decreased after protein oxidation,and covalent cross-linking occurred between protein molecules via disulfide bonds,which was accompanied by an increase in the centrifugal and cooking loss of muscle.The transverse relaxation time(T_2) of muscle was measured by low-field nuclear magnetic resonance(NMR) spectroscopy and the microstructure of muscle was observed by scanning electron microscopy(SEM).It was found that the increase in the centrifugal loss and cooking loss of muscle was due to the destruction of muscle microstructure caused by protein oxidation as well as the decrease in unbound water content and the increase in free water content.Muscle centrifugal loss,cooking loss,free water content and the degree of damage of muscle microstructure at pH 8.0 were lower than those at pH 5.0.The results showed that under the same oxidation condition,yak muscle proteins are more prone to oxidative damage and lower water-holding capacity near the isoelectric point.

关 键 词：牦牛肉 氧化 PH值 持水性 蛋白质结构 

分 类 号：TS251.1[轻工技术与工程—农产品加工及贮藏工程]