Preparation of starch-based nanoemulsion for sustained release and enhanced bioaccessibility of quercetin

Quercetin is an essential flavonoid with various activities, but it has low bioaccessibility and poor stability. In the present study, an oil-in-water nanoemulsion stabilized by octenyl succinic anhydride modified starch (OSA-CS) was prepared for the delivery, controlled release, enhanced bioaccessibility of quercetin and probing the release mechanism of quercetin from the emulsion in the gastrointestinal tract. OSA-CS with higher substitution than commercially available starch was prepared, and quercetin-loaded nanoemulsions with good storage stability were prepared using it as an emulsifier. The encapsulation efficiency of quercetin in this emulsion was 80.3%, and the loading efficiency was 48.8%, higher than the current study. The release mechanism and bioaccessibility of the starch-based quercetin emulsion during in vitro digestion were explored using in vitro oral, gastric, and intestinal digestion models, and the in vivo delivery ability of the quercetin emulsion was verified in mouse experiments. The release of quercetin from the nanoemulsion in the gastrointestinal tract had the highest fit with the Korsmeyer–Peppas model (R2 > 0.99) and had a high fit with the Higuchi model (R2 = 0.8651), suggesting that diffusion and erosion were the primary release mechanisms. In vivo experiments showed that the nanoemulsions prepared in this study had good quercetin delivery properties. The delivery system substantially improved the bioaccessibility of quercetin from 1.90% to 13.4%, which was superior to other emulsion systems.