Physicochemical and digestive properties of curcumin stabilized by quaternized chitosan/sodium alginate nanoemulsion coatings

Curcumin (Cur) is a bioactive substance, but its instability limits its use in the food system. Thus, a new polysaccharide-based coating is developed by combining quaternized chitosan (QCS) with sodium alginate (SA) in this study to improve the bioaccessibility and stability of Cur. The microstructure of the emulsion was characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and low-field pulsed nuclear magnetic resonance imaging (LF-NMR). The thermal, ionic strength, and pH stability of emulsions were measured. Results indicate that QCS/SA (1:1)-Cur is more stable than other three nanoemulsion systems and the encapsulation rate of which reaches 90.62 %. It also shows higher stability in gastric fluid, excellent bioaccessibility and FFAs in intestinal fluid, as well as significant antibacterial property, antioxidant activity and water dispersibility. This study introduces a new method for obtaining stable, functional Cur-coated systems for food applications.