Encapsulation of hydrolysable tannin from pomegranate peel in W/O/W double emulsion: In-vitro digestion, release kinetics, storage and physical stabilities

Abstract

The hydrolysable tannins from pomegranate peel have been known to exert several health benefits, majorly anti-diabetic properties. The study identified polyphenols present in pomegranate peel hydrolysable tannin (PPHT) and examined their physical stability at varying pH (2.0 – 8.0) and temperatures (4, 20 and 40 °C). PPHT showed stability at acidic pH, but conversely, it degraded at neutral and basic pH. Therefore, this work aimed to encapsulate hydrolysable tannins from pomegranate peel in the internal aqueous phase of W/O/W double emulsion. The study revealed that the double emulsion formulated with span 80-to-lecithin ratio of 1:1 (as lipophilic emulsifier) and gum Arabic concentration of > 2% (as hydrophilic emulsifier) increased the storage stability up to 60 days at ambient condition. In-vitro digestibility showed that PPHT was released from the double emulsion in the intestinal phase. Also, more than 3.75 times increase in the bioaccessibility was observed for encapsulated PPHT as compared to crude PPHT. Korsmeyer-Peppas model fitted best with the experimental data, indicating Fickian diffusion as the mechanism of PPHT release from the double emulsion. Furthermore, kinetic stability was observed for the double emulsion throughout the storage at pH 3.0 – 8.0 and at pasteurization temperatures (LTLT and HTST). Thus, these results facilitated the formulation of PPHT encapsulated double emulsion with enhanced bioaccessibility, storage and physical stability.