Influence of anionic alginate and cationic chitosan on physicochemical stability and carotenoids bioaccessibility of soy protein isolate-stabilized emulsions

• Alginate and chitosan as the outer layer of SPI-stabilized droplets have different properties.
• The stability of carotenoids-loaded emulsions was improved slightly in multilayer emulsions.
• Chitosan coating was capable of reducing the lipids digestibility in emulsions.
• Alginate coating has no effect on bioaccessibility of carotenoids.

The influence of the polysaccharides (anionic alginate and cationic chitosan) coating on the physicochemical properties and bioaccessibility of carotenoids-loaded emulsions in vitro digestion was investigated. The stability of carotenoids-loaded emulsions was characterized by droplet size, surface charge, and carotenoids degradation during the storage. Compared with emulsions stabilized by soy protein isolate (SPI) alone, the emulsions stabilized by alginate-SPI had better stability from pH 3 to 7. However, the emulsions stabilized by chitosan-SPI had droplets aggregation at near neutral pH or at high salt concentration (NaCl ≥ 300 mM). The polysaccharide coating can slightly inhibit the degradation of carotenoids. After in vitro digestion, chitosan coating was capable of reducing the lipids digestibility (87.9%) and bioaccessibility of carotenoids in emulsions. However, alginate has no significant effect on the lipid digestion. These results have important implications for protein and polysaccharide-stabilized emulsions using in protection and delivery of bioactive compounds.