乙醇诱导改性对乳清分离蛋白结构及乳化特性的影响

Effects of Ethanol-induced Modification on the Structural and Emulsifying Properties of Whey Protein Isolates

本实验以未经乙醇溶液处理的乳清分离蛋白(Whey protein isolate,WPI)作为对照组,研究不同浓度乙醇(10%、30%、50%和70%,v/v)处理对WPI结构特性和乳化特性的影响。结果表明,乙醇诱导改性会使WPI的二级结构和三级结构发生显著变化。当乙醇浓度低于50%时可以使蛋白结构展开,而乙醇浓度高于50%时会使WPI分子之间通过二硫键形成聚合物。另外,与对照组相比,乙醇改性能够赋予WPI更高的表面疏水性和更佳的乳化特性(包括乳化活性和乳化稳定性),且乙醇浓度为50%时改善效果最为显著(P<0.05)。上述研究结果表明,乙醇诱导改性是一种有效的改善WPI乳化特性的改性方法,从而为蛋白质的改性奠定了理论基础。

This study took the whey protein isolation(WPI)without the treatment of ethanol solution as the control group to investigate the effect of different concentrations of ethanol(10%,30%,50%,and 70%,v/v)on the structural properties and emulsifying capacities of whey protein isolate(WPI).The results showed that the ethanol-induced modification could significantly alter the secondary and tertiary structures of WPI.Moreover,lower concentration(less than 50%)of ethanol could induce the unfolding of the protein structure of WPI,while higher concentration(more than 50%)of ethanol could promote the protein aggregation which mainly through disulfide linkage.Additionally,compared with control group,ethanol-induced modification could endow higher surface hydrophobicity and better emulsifying capacities(including emulsifying activity and emulsifying stability)of WPI,and 50%was the optimal ethanol concentration.This results indicated that the ethanol-induced modification was an effective modification method to improve the emulsifying properties of WPI and laid a theoretical foundation for the modification of proteins.