Binding of Gallic Acid and Epigallocatechin Gallate to Heat-Unfolded Whey Proteins at Neutral pH Alters Radical Scavenging Activity of in Vitro Protein Digests

Yanyun Cao, Youling L. Xiong

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Preheated (80 °C for 9 min) whey protein isolate (HWPI) was reacted with 20, 120, and 240 μmol/g (protein basis) gallic acid (GA) or epigallocatechin gallate (EGCG) at neutral pH and 25 °C. Isothermal titration calorimetry and fluorometry showed a similar trend that GA binding to HWPI was moderate but weaker than EGCG binding. However, the shift of maximal fluorescence emission wavelength in opposite directions in response to GA (blue) and EGCG (red) suggests discrepant binding patterns. Electrophoresis results showed that EGCG induced formation of HWPI complexes while GA only had a marginal effect. Both free and phenolic-bound HWPI exhibited mild antiradical activity. However, when subjected to in vitro digestion, synergistic radical-scavenging activity was produced between the phenolics and peptides with the highest synergism being observed on 120 μmol/g phenolics.

Original languageEnglish
Pages (from-to)8443-8450
Number of pages8
JournalJournal of Agricultural and Food Chemistry
Volume65
Issue number38
DOIs
StatePublished - Sep 27 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

Keywords

  • binding
  • heat-unfolded whey protein isolate
  • in vitro digestion
  • phenolic derivative
  • synergistic radical scavenging activity

ASJC Scopus subject areas

  • General Chemistry
  • General Agricultural and Biological Sciences

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