Effects of anionic polysaccharides on the digestion of fish oil-in-water emulsions stabilized by hydrolyzed rice glutelin.

Abstract

The effects of two anionic polysaccharides (pectin and xanthan gum) on the in vitro lipid digestibility of fish oil-in-water emulsions stabilized by hydrolyzed rice glutelin (HRG) were determined. The emulsions were passed through a simulated gastrointestinal tract (GIT) consisting of mouth, stomach, and small intestine phases. The physicochemical properties of the colloidal particles in the gastrointestinal fluids (mean particle diameter, ξ-potential, and structural organization) were monitored throughout the GIT. In addition, the kinetics of lipid digestion was characterized in the small intestine phase. Interestingly, the addition of polysaccharide led to a marked increase in both the rate and extent of lipid digestion, with the effect depending on polysaccharide type. For instance, the initial rates of lipid digestion were 8.6 ± 0.6, 13.3 ± 0.4 and 16.1 ± 0.6% free fatty acids (FFA) released min-1 for HRG emulsions containing no polysaccharides, pectin, and xanthan gum, respectively. Similarly, the calculated final extents of lipid digestion were 71.9 ± 3.6, 97.7 ± 3.2, and 100.0 ± 3.8%, respectively. This was probably because the polysaccharides inhibited droplet flocculation, thereby increasing the surface area of lipids exposed to the digestive enzymes. Moreover, the polysaccharides may have interacted with other components involved in the lipid digestion process, such as enzymes, bile salts, and calcium ions. Our results may facilitate the design of plant-based functional foods and beverages that can control lipid digestion in the gastrointestinal tract.