磷脂对大豆乳清蛋白乳化特性的影响

摘要

The author studied the nature soybean whey protein (NWSP) and denatured soy whey protein (DWSP) and analyzed the effect of lecithin (Lec) on the emulsion system of soybean whey protein.Furthermore,the emulsifying activity,emulsion stability,surface hydrophobicity of soybean whey protein,ξ-potential,particle size distribution,and laser scanning confocal microscopy of soybean whey protein emulsions were studied before and after lecithin added.The results indicated that comparing with soybean whey protein emulsification system,the emulsifying activity of DWSP-Lec and NWSP-Lec significantly increased,the emulsion particle size distribution span become more narrow,emulsion droplet average particle size decreased;however,the emulsion of ξ-potential value increased,the electrostatic repulsion between emulsion droplet increased.All these effectively prevented the phenomenon such as flocculation,aggregation,and improve the emulsion stability.DWSP-Lec emulsion is more stable than NWSP-Lec emulsion.This may be due to the structural changes of soybean whey protein after heat treatment,and the hydrophobic groups embedded in the protein are exposed and enhanced hydrophobic interaction between whey protein and phospholipid.Synergistic effect between soybean whey protein and lecithin enhanced the emulsifying activity and stabilized the emulsion.%以非变性大豆乳清蛋白(NWSP)及热变性大豆乳清蛋白(DWSP)为研究对象,探究了磷脂(Lec)对NWSP乳液、DWSP乳液的影响,并对Lec添加前后乳化体系的乳化活性、乳化稳定性、大豆乳清蛋白的表面疏水性、ξ-电位、粒径分布、激光共聚焦显微成像(CSLM)等进行表征.研究发现:与纯大豆乳清蛋白乳化体系比较,添加磷脂后的DWSP-Lec乳化体系、NWSP-Lec乳化体系乳化活性显著提高、乳滴平均粒径减小、乳液的ξ-电位值增加,有效阻止了乳滴絮凝聚集乳液稳定性增强,DWSP-Lec乳液稳定性高于NWSP-Lec乳液,这可能是热处理后大豆乳清蛋白分子发生折叠,包埋于蛋白内部的疏水基团及巯基暴露从而增强大豆乳清蛋白与Lec间的疏水交互作用,大豆乳清蛋白-磷脂的协同作用使其乳化活性增强,乳液更趋于稳定.