Cao Yanyun, Xiong Youling L
State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan Univ, Wuxi, Jiangsu, 214122, China.
Dept. of Animal and Food Sciences, Univ. of Kentucky, Lexington, KY, 40546, U.S.A.
J Food Sci. 2017 Feb;82(2):409-419. doi: 10.1111/1750-3841.13607. Epub 2017 Jan 10.
Integration of gallic acid (GA) and its derivative epigallocatechin gallate (EGCG; 20, 120, and 240 μmol/g, protein basis) into whey protein isolate (WPI) at room temperature and pH 3.0 and pH 7.0 was investigated. At pH 7.0, both phenolics caused significant structural changes and EGCG induced greater digestibility of WPI. Total sulfhydryl in WPI decreased from 28.6 to 7.6 μmol/g and surface hydrophobicity declined by nearly 50% with 240 μmol/g EGCG at pH 7.0. Similar but less appreciable changes were produced by GA and at pH 3.0. Isothermal titration and fluorescence quenching tests showed moderately weak binding of WPI with GA but strong binding with EGCG at pH 7.0. Both phenolics at high concentrations lowered the thermal transition temperature of β-lactoglobulin by 0.5 °C to 1.4 °C and promoted its digestion. The phenolics also displayed a remarkable synergism with peptides in the WPI digest exerting radical scavenging activity.
研究了在室温以及pH 3.0和pH 7.0条件下，将没食子酸（GA）及其衍生物表没食子儿茶素没食子酸酯（EGCG；基于蛋白质计，浓度分别为20、120和240 μmol/g）整合到乳清分离蛋白（WPI）中的情况。在pH 7.0时，两种酚类物质均引起了显著的结构变化，且EGCG使WPI的消化率更高。在pH 7.0条件下，当EGCG浓度为240 μmol/g时，WPI中的总巯基从28.6 μmol/g降至7.6 μmol/g，表面疏水性下降了近50%。GA在pH 3.0时也产生了类似但不太明显的变化。等温滴定量热法和荧光猝灭试验表明，在pH 7.0时，WPI与GA的结合较弱，而与EGCG的结合较强。高浓度的两种酚类物质均使β-乳球蛋白的热转变温度降低了0.5℃至1.4℃，并促进了其消化。这些酚类物质还与WPI消化产物中的肽表现出显著的协同作用，具有自由基清除活性。
