Encapsulation of squalene in oil-in-water emulsions: Utilization of heat-polymerized whey proteins as emulsifiers

Oil-in-water emulsions can be used to create edible delivery systems for lipophilic bioactives using effective emulsion stabilizers. In this study, we investigated the influence of temperature (70, 80 and 90 °C) and holding time (10, 20 and 30 min) on the creation of polymerized whey proteins, and then examined their suitability as emulsifiers for forming and stabilizing squalene-loaded emulsions. The degree of protein polymerization increased with holding temperature and time, as shown by an increase in particle size and viscosity of the protein solutions. Similarly, there was an increase in mean particle diameter and apparent shear viscosity for squalene emulsions stabilized by polymerized whey proteins as the holding temperature and time used to create them increased. Polymerized whey proteins produced by heating a whey protein solution (12%) at 70 °C for 10 min gave the highest emulsion stability index of 96.88% without any sedimentation. Relatively small particle size, low polydispersity index and higher zeta potential helped in attributing better stability by resisting the emulsion destabilization factors such as sedimentation and creaming. Our results show that the functionality of whey proteins can be improved by promoting their polymerization using controlled thermal treatments within short period of time.