Effect of soy lecithin concentration on the formation and stability of ultrasound emulsions

Emulsification is a key processing step during the manufacture of dairy beverages. Inadequate emulsification negatively impacts the shelf-life of beverage due to the development of coalescence, flocculation and creaming.Soy lecithin is commonly used to stabilize food emulsions.Recently, consumers identify soy lecithin as an undesirable ingredient, and beverage processors are actively exploring alternatives for soy lecithin.This study focuses on evaluating the effect of lecithin on the stability of emulsions prepared by ultrasonication.Emulsions were manufactured by mixing whey protein concentrate(8%),maltodextrin and sucrose(25%)vegetableoil(4%)and soy lecithin added at different concentrations(0,3and6%). The mixture was emulsified by ultrasonication using an acoustic intensity of either 342.5 ± 5.8, 443.6 ± 7.5, or 524 ± 8.9 kJ m−2s−1.After emulsification, the beverages were stored at 4°C, and the stability was evaluated weekly during 3 weeks.The stability of the ultrasound emulsions was evaluated in terms of particle size, gel electrophoresis, rheological behavior and confocal laser scanning microscope.Overall, the application of ultrasound results in a bimodal distribution of particle ranging from 310 to 748 nm.The lowest range of distribution (270 ± 10.8nm)was observed in those emulsions treated at the highest intensity(524 ± 8.9 kJm−2 s−1).Interestingly, the mean particle size of those samples without lecithin increased during storage from 520 to 750 nm.CLSM images indicated aggregation of proteins during storage as well as larger oil droplet on samples treated at 342.5 ± 5.8 kJ m−2s−1 and 0% lecithin concentration.The rheological analysis revealed that all samples displayed a distinctive viscoelastic region.The linear segment was significantly(P \u3c 0.05)longer in the emulsion formulated with soy lecithin(6%) and treated at 524 ± 8.9 kJ m−2 s−1.In general, the combined effect of soy lecithin and ultrasonication yielded a stronger gel and shear-thinning behavior.The application of ultrasound seems to functionalize whey protein-based emulsifiers via processing and compositional parameters that enhance interactions between ingredients