Kinetic study of d-limonene release from finger citron essential oil loaded nanoemulsions during simulated digestion in vitro

Nanoemulsion loading finger citron essential oil (FCEO) can maintain bioactivities of FCEO and increase its water solubility. In this study, stability of FCEO nanoemulsions during digestion in vitro were evaluated and the release kinetics of d-limonene (the main component in the oil) were developed. Compared with free oil released to maximum for 6 min, all nanoemulsions kept sustainably releasing for 300 min or longer. Droplet size of the nanoemulsions increased from 10–18 nm of initial to 105–1106 nm after digestion, indicating coalescence or aggregation occurred. Zero-order, Hixcon-Crowell, Higuchi, Ritger-Peppas and Niebergull models were used to describe the release kinetics. The results showed zero-order and Ritger-Peppas models were the best fit models at mouth and intestinal stage, respectively. Both zero-order and Higuchi models were appropriate at gastric stage. This study could demonstrate the digestion mechanisms of FCEO loaded nanoemulsion and facilitate the design of hydrophobic nutraceuticals delivery systems in food industry.