Dairy Foods: Dairy Products

摘要

Emulsification is a key processing step during the manufacture of dairybeverages. Inadequate emulsification negatively impacts the shelf-life ofbeverage 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 beverageprocessors are actively exploring alternatives for soy lecithin.This studyfocuses on evaluating the effect of lecithin on the stability of emulsionsprepared by ultrasonication.Emulsions were manufactured by mixingwhey 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 intensityof 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 evaluatedweekly during 3 weeks.The stability of the ultrasound emulsions wasevaluated in terms of particle size, gel electrophoresis, rheological behaviorand confocal laser scanning microscope.Overall, the application ofultrasound results in a bimodal distribution of particle ranging from 310 to748 nm.The lowest range of distribution (270 ± 10.8nm)was observed inthose emulsions treated at the highest intensity(524 ± 8.9 kJm−2 s−1).Interestingly,the mean particle size of those samples without lecithin increasedduring storage from 520 to 750 nm.CLSM images indicated aggregationof proteins during storage as well as larger oil droplet on samples treatedat 342.5 ± 5.8 kJ m−2s−1 and 0% lecithin concentration.The rheologicalanalysis revealed that all samples displayed a distinctive viscoelastic region.The linear segment was significantly(P < 0.05)longer in the emulsionformulated with soy lecithin(6%) and treated at 524 ± 8.9 kJ m−2 s−1.Ingeneral, the combined effect of soy lecithin and ultrasonication yieldeda stronger gel and shear-thinning behavior.The application of ultrasoundseems to functionalize whey protein-based emulsifiers via processing andcompositional parameters that enhance interactions between ingredients.