RESEARCH ARTICLE


Extract of Phenolics From Pomegranate Peels



Zhenbin Wang*, 1, 3, Zhongli Pan2, 3, Haile Ma2, 1, Griffiths G. Atungulu3
1 School of Biological and Environmental Engineering, Jiangsu University, Jiangsu, Zhenjiang 212013, China
2 Processed Foods Research Unit, USDA-ARS-WRRC, Albany, CA 94710, USA
3 Department of Biological and Agricultural Engineering, University of California, Davis, CA 95616, USA


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© 2011 Wang et al.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Processed Foods Research Unit, USDA-ARS-WRRC, Albany, CA 94710, USA; Tel: +1-510-559-5861; Fax: +1-510-559-5851; E-mail: zhongli.pan@ars.usda.gov


Abstract

The effects of different solvents, temperature conditions, solvent-solid ratios and particle sizes on solid-solvent extraction of the total phenolics, proanthocyanidins and flavonoids herein also referred to as antioxidant from pomegranate marc peel (PMP) was studied. Water, methanol, ethanol, acetone, and ethyl acetate extraction efficiencies at extraction times of 0.17 to 10 min, extraction temperatures of 25 to 95°C, ratios of solvent/solid of 5:1 to 50:1 and particle sizes of 10 to 40 mesh were evaluated. At 40 °C, solvent/solid ratio of 15:1, extraction time of 240 min and particle size of 40 mesh, methanol gave the highest extract yield of the total phenolics (8.26%), followed by water (5.90%), ethanol (1.55%), acetone (0.37%), and ethyl acetate (0.18%), respectively. However, at an extraction temperature of 95°C, the total phenolics extract yield with water was 11.15% for particle size of 40 mesh, solvent/solid ratio of 15:1, and extraction time of 2 min. Despite the lowest extract yield at extraction temperature of 40 °C, solvent/solid ratio of 15:1, extraction time of 240 min and particle size of 40 mesh, ethyl acetate extraction gave the highest content of the total phenolics (20.24%), proanthocyanidins (2.65%) and flavonoids (3.92%) in the extract. The DPPH antioxidant activity of extracts had a linear relationship with the total phenolics content in the extracts (R2=0.9779). This study revealed that water extraction, which has the economic and safety merits, can be used as an environmentally friendly method for producing antioxidants from the PMP.

Keywords: Antioxidant, pomegranate, total phenolics, extract, temperature, time, ratio of solvent/solid, particle size, marc, residues.