Unlocking the potential of whey protein isolate: How ultrasonic treatment transforms functionality and structure

This study explores the transformative effects of ultrasonic treatment on the physicochemical, structural, and functional properties of whey protein isolate (WPI). WPI solutions were subjected to ultrasonic treatment at two power levels (300 W and 600 W) for durations of 10 and 20 min. The findings reveal a fascinating interplay between ultrasonic parameters and protein behavior: at 300 W, the treatment induces protein unfolding, while at 600 W, it promotes the formation of large aggregates. These changes are accompanied by significant alterations in secondary structures, with a reduction in β-sheet and α-helix content at 300 W, followed by their re-enhancement at 600 W. Notably, ultrasonication at 600 W significantly enhances di-tyrosine formation, sulfhydryl content, and surface hydrophobicity, compared to untreated samples. Zeta-potential measurements demonstrate a decrease after 10 min of treatment at both power levels, but an increase is observed after 20 min, indicating dynamic shifts in surface charge. Additionally, ultrasonic treatment elevates interfacial tension. WHC increases by 2.2-fold and 3.2-fold after 20 min of treatment at 300 and 600 W, respectively. At 600 W, a marked reduction in solubility and a substantial increase in turbidity are observed, contrasting with the outcomes at 300 W. Despite this, the highest emulsification activity and stability are achieved with WPI treated at 600 W for 20 min, underscoring the potential of ultrasonication to optimize emulsion-based applications. These findings emphasize the critical role of precise control over ultrasonic power and treatment duration to achieve desired functional outcomes.