Objective Chitin is an abundant and sustainable biomaterial with potential applications in foods and other commercial products. At present, there is a poor understanding of the formation and stabilization mechanisms of nanochitin-coated oil droplets, as well as about the impact of the adsorbed nanochitin particles on lipid digestion and nutraceutical bioavailability under gastrointestinal conditions. Methods The formation, stability, and performance of nanochitin-stabilized Pickering emulsions were compared to conventional surfactant-stabilized emulsions. Tween 20, a widely used food-grade non-ionic surfactant was used a model surfactant. Lipid digestion was followed by monitoring the amount of free fatty acid (FFAs) released within the simulated small intestine and nutraceutical bioaccessibility was followed by measuring the amount of nutraceutical solubilized within the mixed micelles. Results The nanochitin-coated oil droplets behaved very differently from the surfactant-coated ones under simulated gastrointestinal conditions. In particular, there was a decrease in lipid digestion of around 30% in the presence of 0.1 wt% nanochitin. This effect was attributed to a number of physicochemical mechanisms: (1) nanochitin promoted droplet flocculation, which reduced the lipid surface area available for the bile salts and lipase to adsorb; (2) the cationic nanochitin may have directly interacted with anionic bile salts, free fatty acids, and lipase, which inhibited lipid digestion and reduced nutraceutical bioaccessibility. Conclusions Nanochitin can be used as a food-grade particle stabilizer in oil-in-water emulsions that inhibits lipid digestion, which may be useful for developing high-satiety foods. However, one must be careful that it does not always inhibit the bioaccessibility of hydrophobic bioactive agents, such as nutraceuticals and oil-soluble vitamins.
