The Effects of Ultrasound Times and Amplitudes on the Particle Size and Emulsifying Properties of Whey Protein Concentrate

Abstract

The current study was conducted to investigate the effects of ultrasound times and amplitudes on the particle sizes and emulsifying properties of samples of whey protein concentrate (WPC). The ultrasound (US) application was performed using VC-7500 ultrasonic power equipment at a 20 kHz frequency, at various times (10, 20, and 30 min at a 50% amplitude) and amplitudes (60%, 80%, and 100% for 5 min). The results showed that the US procedure had a significant effect (p<0.05) on both particle sizes and emulsifying properties (p<0.05). The smallest particle size was obtained for the WPC samples exposed to 30 min of US at a 100% amplitude (US310) (498.6 nm). The WPC samples treated at a 100% amplitude showed a smaller particle size compared to the other WPC samples at 60% and 80% amplitudes. While the WPC samples treated for 10 min had the biggest particle size (790.3 nm), those treated for 30 min had the smallest particle size (697.1 nm). On the other hand, among the treatments, US310 whey protein concentrate samples had the highest EAI (emulsifying activity index) (198 m2/g) and ESI (emulsion stability index) (34.0 min), whereas the untreated WPC samples had the lowest EAI (56 m2/g) and ESI (13.0 min). In general, 30-min US treatment at a 100% amplitude showed the lowest particle size (498.6 nm) and the highest emulsifying properties (EAI: 198 m2/g and ESI: 34.0) compared to the other sonication times and amplitudes.