Mg^(2+)对羊肉肌原纤维蛋白结构和凝胶特性的影响

Effect of Mg^(2+)on the Structure and Gel Properties of Mutton Myofibrillar Protein

通过建立Mg^(2+)-羊肉肌原纤维蛋白(myofibrillar protein,MP)模型,研究Mg^(2+)对MP构效关系和凝胶特性的影响机制。研究发现,随着Mg^(2+)浓度(0、0.01、0.02、0.03、0.04、0.05 mol/L)的增加,羊肉MP的理化特性溶解度、乳化活性、乳化稳定性和粒径显著提升(P<0.05),Zeta电位绝对值下降;MP结构特性:二级结构β-折叠占比显著增加(P<0.05);表面疏水性显著提升(P<0.05);内源色氨酸荧光强度在0.04 mol/L最大;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示肌球蛋白和相关轻链蛋白条带强度增强。MP凝胶特性:羊肉MP流变学分析发现,随着Mg^(2+)浓度增加,储能模量(G’)先升高后降低;与对照组相比,0.03 mol/L Mg^(2+)时,MP凝胶强度提升70.49%;凝胶蒸煮损失、保水性与Mg^(2+)浓度呈负相关(P<0.05);低场核磁共振分析得出随着Mg^(2+)浓度增加,MP凝胶内部不易流动水向自由水状态转化;扫描电子显微镜微观结构观察发现,Mg^(2+)浓度越高,凝胶孔隙越多越疏松;通过相关性分析发现,Mg^(2+)对羊肉MP结构的改变和凝胶特性影响高度相关,Mg^(2+)可以显著提升羊肉MP蛋白的凝胶特性。

In this study,the effect of Mg^(2+)on the physiochemical,structural and gel properties of mutton myofibrillar protein was studied.The results indicated that with an increase in Mg^(2+)concentration(0,0.01,0.02,0.03,0.04 and 0.05 mol/L),the physicochemical properties of mutton myofibrillar protein(MP)including solubility,emulsification activity,emulsion stability and particle size increased significantly(P<0.05),the absolute value of the zeta potential decreased,the proportion ofβ-sheet increased significantly(P<0.05),and surface hydrophobicity increased significantly(P<0.05).The endogenous fluorescence intensity of tryptophan was largest at a Mg^(2+)concentration of 0.04 mol/L.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)showed that the band intensity of myosin and relevant light chain proteins increased.Rheological analysis showed that the storage modulus(G’)first increased and then decreased.Compared with the control group,MP gel strength increased by 70.49%at a 0.03 mol/L Mg^(2+)concentration.Gel cooking loss and water-holding capacity(WHC)were negatively correlated with Mg^(2+)concentration(P<0.05).Low-field nuclear magnetic resonance(NMR)analysis showed that with increasing Mg^(2+)concentration,immobilized water in the MP gel was transformed into free water.Microstructure observed by scanning electron microscopy(SEM)showed that the higher the concentration of Mg^(2+),the more porous the gel.Correlation analysis showed that Mg^(2+)concentration was highly correlated with the structure and gel characteristics of MP.Therefore,Mg^(2+)can significantly improve the gel properties of mutton MP.