Influence of chitosan on stability and lipase digestibility of lecithin-stabilized tuna oil-in-water emulsions

The influence of chitosan concentration (0–0.3 wt%) and molecular weight (120, 250 and 342.5 kDa) on the physical stability and lipase digestibility of lecithin-stabilized tuna oil-in-water emulsions was studied. The ζ-potential, droplet size, creaming stability, free fatty acids and glucosamine released was measured for the emulsions when they were subjected to an in vitro digestion model. The ζ-potential of the oil droplets in lecithin-chitosan stabilized emulsions changed from positive (≈+53 mV) to negative and the emulsions were unstable to droplet aggregation for all chitosan concentrations and molecular weights used after being subjected to the digestion model. The amount of free fatty acid and glucosamine released per unit amount of emulsion was higher when pancreatic lipase was included in the digestion model. These results suggest that lecithin-chitosan coated droplets can be degraded by lipase under simulated gastrointestinal conditions. Consequently, chitosan coated lipid droplets may serve as useful carriers for the delivery of bioactive lipophilic nutraceuticals.