Development of hen egg-based protein beverages with high nutritional value.

Abstract

Physical stability is a prerequisite for any emulsion-based beverage. This study aimed to optimize beverage emulsion (BE) rich in whole egg, whey protein isolate (WPI), and soyabean oil in the presence of polygalactose derivative as adsorbing hydrocolloids (AH) and partially hydrolyzed starch as non-adsorbing hydrocolloids (NAH). All formulations were optimized for stability, particle size, polydispersity index (PDI), and zeta potential (ζ). A central composite design was applied to investigate the impact of WPI concentration, hydrocolloid concentration, oil volume, and pH as independent factors on particle size, PDI, and ζ of emulsions. The optimum conditions were met upon formulating BE with 1 whole egg, 9.28g WPI, 11.24g AH, 5.58mL oil at pH 7. Two optimal formulations were obtained for BE stabilized with NAH at pH 3 and 7, at which droplets had the highest electrical charge. Noting that, less amount of NAH (7.5g) was required at pH 3 than at pH 7 (13.56g). Oil content (3mL) and WPI concentration (16g) for both NAH formulations were similar. The size, polydispersity index (PDI), and zeta potential of AH-stabilized emulsion were 762nm, 0.69, and - 32.05mV, respectively, while for NAH emulsion, they were 150.02nm, 0.40, and - 28.53mV at pH 7; and 248.39nm, 0.41, and 27.1mV at pH 3, respectively. No conspicuous gravitational separation was observed after 20days of storage at 4°C. Hence, both hydrocolloids are appropriate to stabilize protein-enriched BE at neutral pH; however, physical stability was also achieved at acidic pH for NAH-stabilized emulsions.