Interfacial characteristics and digestive kinetics of emulsions fabricated by composite potato and whey protein

Partial substitution of animal protein with plant protein can reduce animal protein consumption and carbon emissions. This study investigated the effects of potato protein (PP) and whey protein (WP) ratios (10/0, 9/1, 7/3, 5/5, 3/7, 1/9 and 0/10, w/w) on the interfacial characteristics and digestive kinetics of composite protein emulsions for substituting WP with PP. Increasing the PP proportion improved the dynamic surface pressure of mixed protein at the oil/water interface while decreasing the interfacial layer dilatational elasticity. Furthermore, a high PP proportion increased the particle size, ζ-potential value, adsorbed protein amount, surface protein load and apparent viscosity of the emulsions. Confocal laser scanning microscopy confirmed that the increased PP proportion led to interfacial protein aggregation, thereby forming a thick and complete interfacial layer. Moreover, it improved the emulsion stability index. In addition, increasing the PP proportion slowed down the release of free fatty acids, but did not influence the release of total and individual fatty acids. Based on emulsification characteristics and digestion rate, the optimal PP/WP radio was found to be 7/3. The findings support the possible use of plant proteins in food items as substitutes for animal proteins.