Gelatin-EGCG-high methoxyl pectin ternary complex stabilized W1/O/W2 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, W1/O/W2 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 W1/O/W2 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 W1/O/W2 double emulsion loaded with vitamin C was released slowly in the small intestine and had a certain sustained-release function.