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.
|Number of pages||11|
|Journal||Journal of Food Science|
|State||Published - Feb 1 2017|
Bibliographical noteFunding Information:
This research was supported by the USDA Natl. Inst. of Food and Agriculture (Hatch project 1005724), and an Oversea Study Fellowship from the China Scholarship Council (to Y.C.). Approved for publication as journal article number 16-07-081 by the Director of the Kentucky Agricultural Experiment Station. The authors declare no conflict of interest.
© 2017 Institute of Food Technologists®
- affinity binding
- in vitro digestibility
- phenolic compounds
- whey protein
ASJC Scopus subject areas
- Food Science