Pressurised water extraction of polyphenols from pomegranate peels

Pomegranate peels are one of the most valuable by-products of the food industry in terms of polyphenols which are conventionally extracted from plant materials by organic solvents, especially with methanol. Pressurised water extraction was investigated for the extraction of polyphenols from pomegranate peels. The most important factors affecting the extraction results were found to be particle size, temperature, and static time. The results indicated that pressurised water extraction was as effective as conventional methanol extraction for the recovery of polyphenols from pomegranate peels. Total phenolic contents of pomegranate peels obtained by pressurised water extraction at optimised conditions and conventional solid–liquid methanol extraction were determined as 264.3 and 258.2 mg/g tannic acid equivalents, respectively. Hydrolyzable tannins were the predominant polyphenols of pomegranate peels corresponding to 262.7 mg/g tannic acid equivalents. Punicalagin content of pomegranate peels by pressurised water extraction was found to be 116.6 mg/g on dry matter basis.