Properties of binary complexes of whey protein fibril and gum arabic and their functions of stabilizing emulsions and simulating mayonnaise

Food protein fibrillization is recently regarded as an attractive strategy to broaden and improve food protein functionality in food science. In the present work, whey protein isolate (WPI) solutions was heated at pH 2.0 and 80 °C for different time (1, 2, 4, 8, and 16 h) to prepare whey protein isolate fibrils (WPF), and the resulting WPF was mixed with gum arabic (GA) at pH 2.0–6.0 to explore the properties and functions of such mixtures. The fibril conversion rate of WPI continued to grow from 4% to 32% with the extension of heating time from 1 to 16 h. The phase behavior study showed that the insoluble WPF-GA binary complexes were formed at pH 4.6–6.0 due to the electrostatic interaction between amino groups of WPI and the carboxyl groups of GA. Compared to the WPI-GA complexes, the WPF-GA complexes had a higher GA content and coacervate yield, suggesting that the fibrillization contributes to the association of proteins with polysaccharides. WPF alone were linear, while fibril bundles appeared in the presence of GA. Such WPF-GA complexes exhibited an excellent capacity to prepare gel-like emulsions. The viscosity and strength of the prepared emulsions was gradually enhanced as the fibril conversion rate of WPI increased. Besides, the complexes of GA and WPF with a heat-treated time of 16 h showed the greatest potential to prepare mayonnaise analogues with a solid-like property, which possessed the similar storage modulus and smoothness to the commercial mayonnaise products.