L-组氨酸修饰乳清蛋白结构及其热诱导凝胶特性

采用L-组氨酸(L-His)作为蛋白凝胶功能性的增强剂,将其加入乳清分离蛋白溶液中制备热诱导凝胶,研究L-His对乳清蛋白结构及其凝胶特性的影响.结果 表明:在乳清蛋白等电点(pI 5.2)时蛋白形成尺度约1 700 nm、具有极小比表面积且几乎不带电的蛋白聚集体,远离蛋白等电点时则所形成的聚集体大小约为400 nm;...

L-Histidine Modifies the Structure and Heat-induced Gel Properties of Whey Protein

L-Histidine(L-His)was added as a functional enhancer of protein gels to whey protein isolate in aqueous solutions to prepare heat-induced gels.The effects of L-His on the structure and gel properties of whey protein were investigated.The results showed that aggregates with a diameter of about 1700 nm and a very small specific surface area,which were found to be almost uncharged,were formed at the isoelectric point(pI 5.2)of whey protein.However,the aggregate size was~400 nm at pH away from the pI.L-His inhibited whey protein aggregation,reduced the aggregate size but dramatically increased the specific surface area,promoted protein unfolding and increased the amount of charge carried by the protein molecule.Whey protein formed a heat-induced white gel with a low water-holding capacity(WHC)at the pI,whereas the gels formed at other pH values were yellow with higher WHC than at the pI and the yellowness was increased as pH was farther away from the pI.Despite having no obvious impact on the color,L-His significantly enhanced the WHC(P<0.05)and improved the textural properties of gels.More notably,the elasticity and chewiness of the gels that were formed at pH 7.59 and 9.74 were significantly improved by L-His(P<0.05).These changes in gel functional properties could be mainly attributed to the fact that L-His could impel the rearrangement of hydrogen bonds,disulfide bridges and hydrophobic interactions involved the gel matrix.Overall,L-His changed the structure of whey protein and improved the gel properties,and its effect was affected by pH.