Influence of emulsifier type on gastrointestinal fate of oil-in-water emulsions containing anionic dietary fiber (pectin)

The influence of emulsifier type and dietary fiber addition on the gastrointestinal fate of emulsified lipids was investigated using a simulated gastrointestinal tract (GIT): mouth; stomach; small intestine. The emulsions tested contained lipid droplets coated with different emulsifiers (sodium caseinate, Tween 80, or lactoferrin), as well as different initial levels of low methoxy pectin (0%, 0.025% and 0.5% w/w). In the absence of pectin, the initial rate of lipid digestion depended strongly on emulsifier type: being 20.5, 18.6, and 6.4 %FFA min−1 for Tween 80, lactoferrin, and caseinate, respectively. However, complete lipid digestion occurred for all these emulsions by the end of the small intestine phase. The slower initial rate of lipid digestion in the caseinate-stabilized emulsions was attributed to extensive droplet flocculation in the gastric phase, which would restrict the access of lipase to lipid droplet surfaces. Pectin addition increased the rate of lipid digestion in caseinate-stabilized emulsions (e.g., by 100% for 0.025% pectin), which was attributed to its ability to suppress droplet flocculation. Conversely, high levels of pectin in the Tween 80- and lactoferrin-stabilized emulsions decreased the initial rate of lipid digestion (e.g., by >35% for 0.5% pectin), possibly due to calcium binding or gel forming effects. These results indicate that the rate and extent of lipid digestion can be controlled by using different emulsifiers or by adding dietary fibers, which may be useful information for the rational design of functional foods and beverages.