Ultrastable emulsions constructed by self-assembly of two protein-polyphenol- anionic polysaccharide ternary complexes-stablized high internal phase emulsions

Abstract

Compared to conventional high internal phase emulsions (HIPEs), ultrastable HIPEs have recently attracted much attention due to much better stability and protection for bioactive compounds. Here, novel food-grade ultrastable HIPEs were successfully constructed. By simply mixing two individual unstable HIPEs (instability in 3 months in open atmosphere) stabilized by ternary complexes of protein (i.e., lactoferrin), two polyphenols (i.e., (−)-epigallocatechin-3-gallate and curcumin) and two anionic polysaccharides (i.e., κ-carrageenan and low methoxylated pectin), respectively, ultrastable mixed-HIPEs (very stable for 1 year or more in open atmosphere) were achieved unexpectedly. The two individual HIPEs underwent liquid-to-gel and viscous-to-elastic transitions during mixing, exhibiting strong structural synergism. The stabilization was ascribed to the electrostatic repulsive interactions and the formed interpenetrating polymer networks hydrogels in continuous phases; their contribution varied according to the binding sequences of protein, polyphenol, and polysaccharide (for ternary complexes) and the combination modes of individual HIPEs (for mixed-HIPEs). The excellent soft material properties of ternary complexes can provide guarantee for the stsability of emulsion droplets, avoiding their rupture caused by strong squeezing in mixed-HIPEs. This finding greatly expands the type of food grade ultrastable HIPEs. Overall, the novel food-grade ultrastable mixed-HIPEs will offer fascinating opportunities for their future applications in food, medical, cosmetic, and tissue engineering products.