Antibacterial activity of crude and nano-pomegranate (Punica granatum L.) peel powder extracts

Abstract

The use of synthetic chemically antimicrobials is a common practice in food preservation to prevent spoilage and pathogen contamination. Currently this is undesirable for most of the consumer who prefer natural safe food. This study was performed to prepare and characterize pomegranate nanoparticles NPP45 and NPP90 by ultrafine mechanical ball milling of crude pomegranate peels powder CPP for 45 and 90 minutes. Extraction with different solvents were subjected to determination of total phenols (μg gallic acid equivalent GAE/ml extract). The antibacterial activity of CPP, NPP45 and NPP90 methanolic extracts were examined. Ultrafine pall milling of CPP for 45 and 90 minutes is sufficient to decrease the original particle size to the nanoscale. Particle size means of NPP45 and NPP90 were 373 and 125nm, respectively. The highest phenolics content was 93.6±2.1 μg GAE ml−1 in NPP90 methanolic extract compared to CPP extract that contained 56.9±1.3 μg GAE ml−1 with 39.21% increase. CPP, NPP45 and NPP90 methanolic extracts showed significant inhibit the growth of all tested bacterial strains; however, NPP45 and NPP90 methanolic extracts exhibited as strong antibacterial activity compared to CPP extracts. The most sensitive tested bacterial strains; B. subtilis, St. aureus, L. monocytogenes and Psud. aeruginosa with minimum inhibitory concentrations (MICs) values ringing (6–8 mg/ml) in the presence of both CPP and NPP45 methanolic extracts and with values of MICs (4 mg/mL) in the presence of the methanol extract NPP90. Finally, CPP, NPP45 and NPP90 represent unique natural materials rich in phenolics with strongly antibacterial efficiency and potential applications in the food industry as a natural alternative to chemically synthetic antimicrobial agents.