ARS | Publication request: Extraction of phenolics from pomegranate peels

Submitted to: Open Food Science Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 2, 2010
Publication Date: May 1, 2011
Citation: Wang, Z., Pan, Z., Ma, H., Atungulu, G.G. 2011. Extraction of phenolics from pomegranate peels. Open Food Science Journal. (5):17-25.

Interpretive Summary: Pomegranate is currently an important and high value product in the agricultural market. The processing of pomegranate juice involves squeezing juice from the fruit with the seeds and the peels together. The resulting marc on a weight basis consists of approximately 73 % peels and 27% seeds and has a high potential for value addition as a source of antioxidants. In this study, efficient methods for extraction of the antioxidants embedded in the pomegranate peels such as phenolics, proanthocyanidins and flavonoids and the determination of their extraction kinetic parameters which are important for designing an efficient extraction process are studied and reported.

Technical 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.