Hydroxyl Radical-Stressed Whey Protein Isolate: Chemical and Structural Properties

Xuhai Cui, Youling L. Xiong, Baohua Kong, Xinhuai Zhao, Ning Liu

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


Many whey protein-containing foods are prepared in the presence of reactive oxygen species generated during processing. The objective of the present study was to determine chemical and structural changes, including carbonyls, sulfhydryls (SHs), dityrosine, surface hydrophobicity, turbidity, and cross-linking, in whey protein isolate (WPI) exposed to FeCl 3/H 2O 2 hydroxyl radical-generating systems (HRGS) at room temperature (20 °C). Protein carbonyl content in WPI increased (P<0.05) with increasing concentrations of H 2O 2 when incubated for up to 10 h; total SH groups decreased (P<0. 05) in a similar fashion. The HRGS-oxidized WPI also showed a higher dityrosine content, surface hydrophobicity, and turbidity (P<0. 05) than nonoxidized WPI. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed substantial losses of β-lactoglobulin, α-lactalbumin, and bovine serum albumin, and a concomitant formation of protein polymers in oxidized WPI. The protein-oxidation indexes were all significantly correlated (P<0. 01). These oxidation-induced changes demonstrate high susceptibility of WPI to oxidative stress at room temperature and may explain variations in functionality of whey proteins often observed in formulated foods.

Original languageEnglish
Pages (from-to)2454-2461
Number of pages8
JournalFood and Bioprocess Technology
Issue number6
StatePublished - Aug 2012

Bibliographical note

Funding Information:
Acknowledgments This study was supported by National Natural Science Foundation in China (Grant No. 30871818) and Foundation of Innovative Research Team of Higher Education of Heilongjiang Province (Grant No. 2010td11).


  • Chemical and structural properties
  • Hydroxyl radical
  • Protein oxidation
  • Whey protein isolate

ASJC Scopus subject areas

  • Food Science
  • Safety, Risk, Reliability and Quality
  • Process Chemistry and Technology
  • Industrial and Manufacturing Engineering


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