Tea polyphenols on emulsifying and antioxidant properties of egg white protein at acidic and neutral pH conditions

The influence of tea polyphenol (TP) treatment on the emulsifying, antioxidant and structural properties of egg white protein (EWP) at acidic (pH 3.8) and neutral (pH 7.0) pH conditions were completely evaluated. The emulsifying activity of EWP was significantly improved after TP treated at pH 7.0 (p < 0.05), but it is negatively correlated with TP concentration. TP treatment at pH 7.0 and 3.8 could significantly improve the antioxidant activity of EWP (p < 0.05). TP treated at pH 3.8 could significantly increase the average particle sizes of EWP aggregates, especially at higher TP concentration, thus impair to the emulsifying behavior. The affinity of EWP with TP at pH 7.0 was stronger than that at pH 3.8, thereby reducing the surface hydrophobicity and isoelectric point. In conclusion, the results of this work could provide a theoretical basis for the development of bifunctional nutrients with both antioxidant and emulsifying properties.