Inhibition of Salmonella enterica and Enterohemorrhagic Escherichia coli by Ethanolic Extracts of Pomegranate Peels

This study compared the effect of phenolics extracted from four different types of pomegranate peels for controlling the growth of Salmonella enterica and enterohemorrhagic Escherichia coli. Cells of the two bacterial cultures (5 log CFU/mL) were treated in tryptic soy broth containing 0, 1, or 2% ethanolic extracts of four pomegranate peels for 5, 10, or 24 h at 25 °C. The surviving cells were recovered on a general-purpose agar and a selective medium. The extracts of three products were more effective (p ≤ 0.05) against E. coli than the extract of the remaining product, which had a similar activity to the extracts of two of the products used against S. enterica. Longer treatment time and higher extract concentration resulted in greater pathogen population reductions. The bacterial strains used had varied susceptibility to the extracts. Reductions in cell population positively correlated with the total contents of hydrolyzable tannins in the treatment systems. These findings suggested that ethanolic extracts of evaluated pomegranate peels had inhibitory activities against the two bacterial pathogens. This highlights the potential of pomegranate peels as a promising natural alternative to conventional antimicrobials for controlling foodborne pathogens like S. enterica and E. coli.