Enzyme-assisted supercritical fluid extraction of phenolic antioxidants from pomegranate peel

Abstract

This study presents a comprehensive enzyme-assisted supercritical fluid extraction (EASCFE) process developed to extract antioxidant phenolics from pomegranate peel (PP). Pomegranate peel collected from local agro-processing units was treated with various commercial and feed enzyme preparations. The morphological changes in the ultrastructure of PP cell wall after enzyme treatment were visualized by field emission scanning electron microscopy (FESEM). Extraction of antioxidant phenolics from enzyme pretreated PP was carried out by supercritical carbon dioxide (SC-CO2) with ethanol as a co-solvent. The extracts produced were investigated for their total phenolics (TP), antioxidant activity and phenolic acids profile using HPLC-DAD-ESI–MS. The observed results showed that EASCFE doubled the recovery of crude extracts with increased level of phenolic constituents (TPs), and improved radical scavenging capacity (RSC), trolox equivalent antioxidant capacity (TEAC) and inhibition of linoleic acid peroxidation. HPLC-DAD-ESI–MS characterization of the extracts authenticated the presence of vanillic (108.36μg/g of extract), ferulic (75.19μg/g of extract) and syringic (88.24μg/g of extract) as potent phenolic acids. The results of this study support that EASCFE can be explored as a state-of-the-art green technological process for recovering optimum amounts of antioxidant phenolics from under-utilized pomegranate peel or other such materials. In addition, retention of appreciable level of naturally occurring vanillic, ferulic, and syringic acids in the enzyme-extracted components advocates that EASCFE is a good choice for preparation of PP extracts for food preservation as well as for the development of nutraceuticals and chemo-preventive phytomedicine.