Contribution of soybean polysaccharides in digestion of oil-in-water emulsion-based delivery system in an in vitro gastric environment

This study aims to evaluate the effects of soy soluble polysaccharide and soy hull polysaccharide on stability and characteristics of emulsions stabilised by soy protein isolate in an in vitro gastric environment. Zeta potential and particle size were used to investigate the changes of physico-chemical and stability in the three emulsions during in vitro gastric digestion, following the order: soy protein isolate-stability emulsion < soy protein isolate-soy soluble polysaccharide -stability emulsion < soy protein isolate-soy hull polysaccharide-stability emulsion, confirming that coalescence in the soy protein isolate-stability emulsion occurred during in vitro gastric digestion. Optical microscopy and stability measurement (backscattering) also validate that addition of polysaccharide (soy soluble polysaccharide and soy hull polysaccharide) can reduce the effect of simulated gastric fluid (i.e., pH, ionic strength and pepsin) on emulsion stability, especially, soy protein isolate-soy hull polysaccharide-stability emulsion, compared with soy protein isolate-stability emulsion. This suggests that the flocculation behaviours of these emulsions in the stomach lead to a difference in the quantity of oil and the size and structure of the oil droplets, which play a significant role in emulsion digestion in the gastrointestinal tract. This work may indicate a potential application of soy hull polysaccharide for the construction of emulsion food delivery systems.