Preparation of pure ellagic acid from waste pomegranate peel by supramolecular solvent based heat assisted extraction followed by liquid–liquid extraction and antisolvent precipitation

Abstract

In this study, the applicability of supramolecular solvents (SUPRAS) produced by adding water to colloidal suspensions of four bioamphiphiles, namely n-hexanoic acid, n-heptanoic acid, n-octanoic acid, and n-nonanoic acid, in ethanol for the vortex assisted extraction of ellagic acid (EA) from waste pomegranate peel (WPP) was investigated, respectively. SUPRAS prepared by n-hexanoic acid/ethanol/water (30/30/40, w/w/w) and n-heptanoic acid/ethanol/water (10/30/60, w/w/w) showed better extraction efficiency in comparison with other SUPRAS. The influence of helper methods (vortex, ultrasound, and heat) and solid/solvent ratio on the extraction of EA using the above two SUPRAS was studied. SUPRAS-based heat assisted extraction was considered as the optimal one for the extraction of EA for WPP (SUPRAS was prepared by n-hexanoic acid/ethanol/water, 30/30/40, w/w/w). Other operation parameters, i.e. process temperature and extraction time, were also investigated. And then, the SUPRAS extract was further purified by liquid–liquid extraction using water and ethyl acetate as extraction solvents successively. Finally, pure EA was recovered from the crude EA product by antisolvent precipitation using tetrahydrofuran as solvent and water as antisolvent. Under optimum conditions, the content of EA in the final product was 95.6% and the total yield was about 75%.