THE EFFECT OF ULTRASOUND TIMES AND AMPLITUDES ON THE NANOEMULSIONS CHARACTERIZATION AND LIPID OXIDATION OF WHEY PROTEIN NANOEMULSIONS DURING STORAGE

Abstract

The current work was conducted in order to explore the influence of ultrasound times and amplitudes on the characterization (droplet size, turbidity, and emulsion stability) and lipid oxidation of whey protein nanoemulsions (WPN). Ultrasound (US) application was employed using a VC-750 ultrasonic power equipment with the frequency of 20 kHz at various times (10, 20, and 30 minutes at 50% amplitude) and amplitudes (60%, 80%, and 100% for 5 min). The outcomes exhibited that the US process have a significant impact on both functional properties and lipid oxidation (p<0.05). The smallest droplet size was obtained for the samples exposed to 30 min US at 100% amplitude (608.3 nm). WPN samples treated at 100% amplitude showed smaller droplet sizes compared to the other samples at 60% and 80% amplitudes. While the droplet size of WPN samples treated with 10 min showed biggest droplet size (895.2 nm), samples treated with 30 min showed the smallest droplet size (795.1 nm) in terms of ultrasound times. There is a positive relationship between the variables of droplet size and turbidity. All US-treated WPN samples exhibited less turbidity and smaller droplet size where the control WPN samples demonstrated most turbid structure with the biggest droplet sizes. In addition, the best emulsifying properties (EAI: 255.08 m2 /g and ESI: 43 min) was obtained for the samples exposed to 30 min US at 100% amplitude (US310). The same sample showed the least lipid oxidation during 7 days of storage.