In this work, seven different extracts from pomegranate (Punica granatum L., cv. Hicaz nar) peel were prepared by using different solvents (ethanol, methanol, either alone or in combination with acid, acetone and water). The phenolics (punicalagins and ellagic acid), organic acids (citric acid and malic acid) and sugars of pomegranate peel extracts were determined. The highest amounts of punicalagins and ellagic acid were detected by ethanol-acid extract as 13.86% and 17.19% (w/v) respectively, whereas the lowest levels were obtained with acetone and water extracts. Moreover, the methanol-acid (3.19% malic acid) and ethanol-acid (1.13% citric acid) extracts contained the highest levels of organic acids. The antimicrobial activities of extracts were investigated by agar well diffusion method. Methanol-acid and ethanol-acid extracts exhibited the highest antimicrobial effects on all tested microorganisms, giving inhibition zones ranging in size from 17 to 36 mm. Although similar antimicrobial activities were observed by ethanol, methanol, and acetone extracts (up to 24 mm), the lowest antimicrobial activities were attained by water extract (0-15 mm). All extracts were generally more effective against Gram-positive bacteria: Enterococcus facealis, Bacillus subtilis, Bacillus cereus than Gram-negative ones: Escherichia coli and Enterobacter aerogenes. It was shown that extracts from pomegranate peels represent a good source of bioactive compounds.

In this study, the antibacterial and antibiofilm properties of pomegranate (Punica granatum L.) extracts (PPLs) prepared by 10g of pomegranate peels (PPL10) and 100 mL of different solvents (ethanol, methanol, and their acid combinations, and water) were investigated as sources of bioactive compounds against food related bacteria. The antimicrobial activities of the extracts were measured by using agar well diffusion assay. The acid-treated extracts exhibited the highest antimicrobial activities (31-34 mm). The biofilm formations were assessed by using a microplate reader (570 nm) after crystal violet staining. The prevention and removal of bacterial biofilms were also evaluated by using extracts prepared by 5g of initial pomegranate peel (PPL5) with the different solvents or 200 ppm chlorine solution. All PPL5 and PPL10 extracts diluted at different ratios inhibited and removed biofilms and the highest antibiofilm effects were up to 80% by acidtreated extracts. In addition, PPL5s and PPL10s were as effective as or more effective than chlorine for the prevention of biofilms. Therefore, from an economical perspective the PPL5s could represent promising candidates as natural antibiofilm agents for food industry.

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