丙二醛氧化对牦牛肉肌浆蛋白理化特性及色泽稳定性的影响

Effect of Malondialdehyde Oxidation on Physicochemical Properties and Color Stability of Yak Meat Sarcoplasmic Proteins

利用不同浓度丙二醛(malondialdehyde,MDA)氧化牦牛肉源肌浆蛋白(sarcoplasmic proteins,SP),通过评价SP侧链氨基酸氧化情况、蛋白结构、色泽、肌红蛋白(myoglobin,Mb)氧化状态,探讨脂质氧化对牦牛肉SP理化特性及色泽稳定性的影响。结果表明:经过MDA氧化后,SP的a^(*)值、b^(*)值、C^(*)值、脱氧肌红蛋白含量和氧合肌红蛋白含量均显著降低(P<0.05),L^(*)值、高铁肌红蛋白含量和超铁肌红蛋白浓度均显著升高(P<0.05),即MDA氧化导致色泽稳定性降低。SP的羰基含量、二聚酪氨酸含量、SP-MDA加合物荧光强度、β-螺旋和β-转角相对含量均显著升高(P<0.05),总巯基含量、表面疏水性、内源荧光强度、α-螺旋和无规卷曲相对含量均显著降低(P<0.05),十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果显示小分子条带的模糊扩展和高分子聚集物的形成,反映MDA促进了SP的氧化、聚集。Pearson相关性分析揭示了MDA氧化、SP理化性质、色泽稳定性三者之间的强相关性(P<0.05)。本研究认为,MDA通过直接氧化SP和间接介导Mb氧化改变了SP结构,并导致SP交联聚集和色泽稳定性降低。

Sarcoplasmic proteins(SP)derived from yak meat were oxidized by malondialdehyde(MDA)at different concentrations.The effects of lipid oxidation on physicochemical properties and color stability of SP were investigated by evaluating side-chain amino acid oxidation,protein structure and color of SP and the oxidation status of myoglobin(Mb).The results showed that after MDA oxidation,the a^(*)value,b^(*)value,C^(*)value,and deoxymyoglobin and oxymyoglobin contents of SP significantly decreased(P<0.05),and the L^(*)value,metmyoglobin content,and ferrylmyoglobin concentration significantly increased(P<0.05),indicating that MDA oxidation lowered color stability.The contents of carbonyl groups and dimeric tyrosine,the fluorescence intensity of SP-MDA adducts,and the relative contents ofβ-helix andβ-turn significantly increased(P<0.05),and total sulfhydryl content,surface hydrophobicity,intrinsic fluorescence intensity,and the relative contents ofα-helix and random coil significantly declined(P<0.05).Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)showed blurred expansion of small molecule bands and the formation of macromolecular aggregates,suggesting that MDA promoted the oxidation and aggregation of SP.Pearson correlation analysis revealed significant correlations between MDA oxidation and physicochemical properties and color stability of SP(P<0.05).This study reveals that MDA alters the structure of SP by directly oxidizing it or mediating Mb oxidation,causing cross-linked aggregation of SP and reducing its color stability.