Influence of Hydrocolloids (Dietary Fibers) on Lipid Digestion of Protein-Stabilized Emulsions: Comparison of Neutral, Anionic, and Cationic Polysaccharides

The impact of dietary fibers on lipid digestion within the gastrointestinal tract depends on their molecular and physicochemical properties. In this study, the influence of the electrical characteristics of dietary fibers on their ability to interfere with the digestion of protein-coated lipid droplets was investigated using an in vitro small intestine model. Three dietary fibers were examined: cationic chitosan; anionic alginate; neutral locust bean gum (LBG). The particle size, -potential, microstructure, and apparent viscosity of -lactoglobulin stabilized oil-in-water emulsions containing different types and levels of dietary fiber were measured before and after lipid digestion. The rate and extent of lipid digestion depended on polysaccharide type and concentration. At relatively low dietary fiber levels (0.1 to 0.2 wt%), the initial lipid digestion rate was only reduced by chitosan, but the final extent of lipid digestion was unaffected by all 3 dietary fibers. At relatively high dietary fiber levels (0.4 wt%), alginate and chitosan significantly inhibited lipid hydrolysis, whereas LBG did not. The impact of chitosan on lipid digestion was attributed to its ability to promote fat droplet aggregation through bridging flocculation, thereby retarding access of the lipase to the droplet surfaces. The influence of alginate was mainly ascribed to its ability to sequester calcium ions and promote depletion flocculation. Practical Application The incorporation of dietary fibers into food emulsions was shown to alter the rate and extent of lipid digestion by an amount that depended on fiber type and concentration. A better understanding of the impact of dietary fibers on lipid digestion could be useful for fabricating functional foods that control energy intake and thereby improve human nutrition.