发酵对酸肉蛋白质结构的影响

Structural Changes of Proteins during the Fermentation of Sour Pork

以猪背最长肌为原料制备酸肉,研究蛋白质结构在发酵中的变化。结果表明,随发酵时间延长,蛋白质静电作用力逐渐减弱,疏水相互作用和二硫键作用显著增强后呈小幅度波动变化。蛋白紫外吸收结果显示,肌原纤维蛋白芳香族氨基酸残基偏向更加疏水的环境移动,肌浆蛋白酪氨酸、色氨酸残基微环境极性增加。内源荧光图谱显示,荧光强度总体呈下降趋势且相对发酵0 d时发生红移,表明色氨酸发生了氧化降解,其残基主要暴露到极性环境中。拉曼光谱分析表明,随发酵进行,蛋白质α-螺旋减少,β-折叠增多,发酵110 d酸肉蛋白二级结构可能发生了重排现象。结果表明长时间发酵可使酸肉蛋白质二级结构和三级结构发生变化,这些变化可从蛋白质结构水平上解释发酵对酸肉品质的影响。

Sour pork was prepared from pork longissimus dorsi muscle and the structural changes of proteins were studied during the fermentation process of sour pork. The results showed that the electrostatic force of proteins decreased with fermentation time, while the hydrophobic interaction and the disulfide bonding increased significantly followed by small fluctuations. The results of ultraviolet absorption spectroscopy showed that the aromatic amino acid residues of myofibrillar proteins were shifted to a more hydrophobic environment, and the polarity of the microenvironment around sarcoprotein tyrosine and tryptophan residues increased. The endogenous fluorescence spectra showed that the fluorescence intensity decreased generally, and red shift occurred when compared with before fermentation, which indicates that tryptophan underwent oxidative degradation, and its residues were mainly exposed to the polar environment. Raman analysis showed that the α-helical content decreased, while the β-sheet content increased gradually, and the secondary structure of proteins was reorganized after 110 days of fermentation. These results showed that long-time fermentation could change the secondary and tertiary structures of proteins in sour pork, which explains the effect of fermentation on sour pork quality at the level of protein structure.