茶多酚改性对蛋清蛋白凝胶特性的影响及机理

Effect and Mechanism of Modification with Tea Polyphenols on the Gel Properties of Egg White Protein

研究不同添加量的茶多酚改性对蛋清蛋白凝胶特性的影响,并对其影响机理进行探讨。结果表明:蛋清蛋白的凝胶强度和持水性随茶多酚添加量的增加而逐渐增大,茶多酚添加量为0.8%时蛋清蛋白的凝胶强度提高了130.2%,失水率从29.41%降至19.29%。经茶多酚改性后蛋清蛋白的凝胶网络结构更加有序,凝胶表面更加平滑均匀,蛋白的表面疏水性和表面巯基含量增加,而总巯基含量下降。差示扫描量热分析和傅里叶变换红外光谱进一步分析表明,茶多酚改性作用增加了蛋清蛋白的热稳定性,且蛋白的二级结构发生改变,表现为蛋白结构由有序变为无序,α-螺旋相对含量下降,β-折叠相对含量则明显上升。

The effect of adding different amounts of tea polyphenols on the gel properties of egg white protein was examined and the mechanism underlying the interaction between protein and tea polyphenols was investigated.The results showed that the gel strength and water-holding capacity of egg white protein increased with the increase of tea polyphenols;the gel strength increased by 130.2%,while expressible moisture content of the gel decreased from 29.41%to 19.29%when 0.8%of tea polyphenols were added.The gel network structure of egg white protein modified by tea polyphenols was more compact with a smoother and more uniform surface.The surface hydrophobic and surface SH content of the modified egg white protein increased,while the total SH content decreased.Furthermore,differential scanning calorimetric(DSC)and Fourier transformed infrared spectroscopy(FTIR)analysis showed that modification with tea polyphenols increased the thermal stability of egg white protein and changed the secondary structure;it changed the structure of protein from a state of order to disorder,and resulted in a decrease inα-helix percentage and an increase inβ-sheet percentage.