The effect of different solvents on extraction efficiency in recovery of pomegranate wastes

Pomegranate marc (peel and seed) constitutes almost ̴50% of fruit, and is a rich source of hydrolysable tannins, phenolic acids, anthocyanins, and flavonoids. Due to the high antioxidant and antimicrobial potential of these polyphenols, utilization of pomegranate marc has been gaining interest. Extraction is the main processes to effective utilization of these polyphenols and extraction method is closely related to recovery yield. However, organic solvents that are used in conventional extraction method are shown adverse effects on human health and environment in addition to low extraction efficiency. Therefore, the conventional method and solvents have commenced to be replaced by environment friendly and green alternatives. In this study, ultrasound assisted deep eutectic solvent extraction was used for recapturing the bioactive polyphenols from pomegranate peel and seeds. Ultrasound assisted (UA) extraction was carried out with 9 different DES that were prepared at different molar concentration of HBA (choline chloride) and HBD (glucose, fructose, sucrose, lactic acid, oxalic acid, acetic acid, and glycerol). UA extraction was also carried out with ethanol (50%), methanol (50-100%) and water to compare extraction efficiency of conventional extraction (CE) solvents and DES. Total phenolic content (TPC), total monomeric anthocyanin (TA), total condensed tannin (TCT), hydrolysable tannin content (HTC) and antioxidant activity (DPPH; ABTS) were measured in UADES and CE samples. Furthermore, antimicrobial activity on S. aureus and E. coli was evaluated in these peel and seed extract. Results showed that unlike pomegranate seeds (<6 mm), peel extract have antimicrobial effect on S. aureus (14-18 mm) and E. coli (11-15 mm). Pomegranate peel extracts (45,3-150,8 mol TEAC/g, ABTS) are also better source of antioxidant compounds when compared seed extract (2,50-6,20 mol TEAC/g, ABTS). In this study, choline chloride:glucose (DES-1) was found significantly effective on recovery of polyphenols from pomegranate peel (p<0.05). Choline chloride:fructose extract (DES-9) is evaluated as a significant alternative of CE to recovery of polyphenols from pomegranate seed (p<0.05). Consequently, ultrasound assisted deep eutectic solvent extraction has great potential as a green and efficient alternative for conventional solvent.