Ultrasonic modification of whey protein isolate: Implications for the structural and functional properties

The present study aimed to investigate the implications of ultrasonic treatment on the conformational and functional properties of whey protein isolate (WPI). SDS-PAGE showed that ultrasonication did not change the molecular weight of WPI. FTIR spectroscopy demonstrated that sonication caused secondary structure alterations in WPI, with a reduction in α-helix and β-sheet, and an enhancement in β-turn, and random coil content. An increase in surface hydrophobicity was observed after ultrasound treatment, suggesting that modification in tertiary structure of WPI were induced by sonication. The sizes of aggregates in WPI were found reduced after sonication by the analysis of particle size distribution and scanning electron microscopy (SEM). Additionally, the foaming, emulsifying and antioxidant attributes of WPI were enhanced after treated with ultrasonication. These results suggest that ultrasonication can be used as a useful technology to modify the functional characteristics of whey proteins.