Physicochemical properties, in vitro digestibility and antioxidant activity of dry-heated egg white protein

Egg white powder is widely used as a food ingredient instead of fresh eggs. Dry heat treatment plays an essential role in the processing of egg white powder to obtain its excellent functionalities. In this study, the effect of dry heat treatment on egg white protein (EWP) was evaluated by determining its physicochemical properties and in vitro pepsin digestion. The results indicated that dry heat treatment reduced EWP thermal stability and tryptophan fluorescence and increased its surface hydrophobicity. SDS-PAGE revealed that abundant soluble aggregates formed during dry heating, and these aggregates could be digested by pepsin. The digestibility of dry-heated EWP was better than for untreated EWP, and the essential amino acid and low-molecular-weight peptide (Mw < 1 kDa) contents increased with increasing dry heating time. In vitro digests of EWP that were dry heat treated for 9-15 days exhibited excellent antioxidant properties.