Chitosan decoration enhanced the thermal and ultraviolet resistance of vitamin A-vitamin D coencapsulated in OSA starch-stabilized emulsion by regulating viscoelasticity, interfacial thickness and structure

Abstract

In this study, octenyl succinic acid sodium starch (OSAS) decorated with chitosan (CS) of different molecular weights (50–150 kDa) and concentrations (10–30 mg/mL) was used to stabilize an emulsion coencapsulating with vitamin A (V_A) and vitamin D (V_D). The effect of CS decoration on the thermal and UV stability of the emulsion, as well as the underlying mechanism, was elucidated. The incorporation of CS increased the retention rates of V_A and V_D by 11.36–25.52 % and 3.65–20.54 %, respectively, when exposed to 100 °C for 30 min, and by 13.35–33.05 % and 15.97–37.49 %, respectively, under ultraviolet (UV) exposure for 12 h, respectively. The OSAS/CS complexes were absorbed at the oil–water interface through electrostatic interactions and hydrogen bonding, forming thick interfacial film barriers, and regulating emulsion viscoelasticity to achieve protection against thermal and UV damage. CS decoration increased the thickness, relative crystallinity, and thermal degradation resistance of the interfacial films to mitigate thermal interference with the emulsion. The OSAS/CS complex barriers shielded UV by forming longer molecular chains or ring structures at the interface, enhancing amide functionality, and promoting intermolecular hydrogen bonding. This research could provide a reference for designing practical delivery systems for heat-sensitive and UV-sensitive nutrients like V_A and V_D.