Gelatin-EGCG-high methoxyl pectin ternary complex stabilized W/O/W double emulsions loaded with vitamin C: Formation, structure, stability, in vitro gastrointestinal digestion.

Vitamin C is an essential nutritional supplement and antioxidant in food. However, the development of vitamin C in the food industry is limited due to its extremely poor chemical stability. In this study, W/O/W double emulsions loaded with vitamin C were prepared, and their structure, physicochemical stability, and in vitro gastrointestinal digestion were investigated. The results manifested that the encapsulation efficiency was the highest (90.23 ± 0.49 %) when the addition of vitamin C in the internal aqueous phase was 0.05 %. Storage stability revealed that no phase separation occurred and did not show stratification in the emulsion system during storage, and the physical stability was excellent. pH stability demonstrated that the W/O/W double emulsion loaded with vitamin C had a lower polydispersity index (PDI) value (0.19 ± 0.01) and greater absolute zeta potential value (40.37 ± 0.48) in alkaline environment (pH 8.0-12.0). The ionic stability suggested that the double emulsion was less stable in the presence of sodium ions. In vitro gastrointestinal digestion indicated that the bioavailability of vitamin C was 25 % after simulated digestion in vitro, elucidating that the W/O/W double emulsion loaded with vitamin C was released slowly in the small intestine and had a certain sustained-release function.