Effect of pH and Heat Treatment on the Antioxidant Activity of Egg White Protein-Derived Peptides after Simulated In-Vitro Gastrointestinal Digestion

Authors

Priyanka Singh Rao, National Dairy Research Institute (ICAR-NDRI)Follow
Emerson Nolasco, University of Nebraska- LincolnFollow
Akihiro Handa, Institute of Technology Solution, R&D DivisionFollow
Michael J. Naldrett, University of Nebraska - LincolnFollow
Sophie Alvarez, University of Nebraska-LincolnFollow
Kaustav Majumder, University of Nebraska - LincolnFollow

ORCID IDs

https://orcid.org/0000-0003-2094-7835

Document Type

Article

Date of this Version

2020

Citation

Antioxidants 2020, 9, 1114; doi:10.3390/antiox9111114

Comments

2020 by the authors

Abstract

The study aimed to analyze pH and heat treatment’s effect in modulating the release of peptides with antioxidant activity after simulated gastrointestinal (GI) digestion of Egg white powder (EWP). EWP samples with neutral (EWPN) and alkaline (EWPA) pH were heat-treated at 20, 60, and 90 ◦C and analyzed for protein aggregation, solubility, and GI digestibility. Heat treatment decreased solubility and induced protein aggregation, which was higher for EWPN as compared to EWPA. The unfolding of EWPA proteins at 60 ◦C exhibited a higher GI digestibility and antioxidant activity via Oxygen Radical Absorbance Capacity (ORAC) assay as compared to EWPN. Interestingly, a reverse trend was observed in the cellular antioxidant assay, and the GI-digest of EWPN exhibited a higher antioxidant activity. The LC-MS/MS analysis are in concordance with cellular antioxidant activity assay and showed a higher intensity for peptides with potential antioxidant activity in the GI-digest of EWPN. The results indicate that heat treatment but not the pH is a critical factor in improving the protein digestibility and releasing peptides with antioxidant activity after GI digestion.