Effectiveness of a pomegranate peel extract (PGE) in reducing Listeria monocytogenes in vitro and on fresh-cut pear, apple and melon

Pomegranate peel extract (PGE) is a new promising natural alternative control substance with large spectrum of activity against wide range of pathogenic microorganisms. In the present study, PGE was firstly investigated as natural antimicrobial against Listeria monocytogenes both in vitro and on fresh-cut fruits. The in vitro results showed quick and strong bactericidal and bacteriostatic activity against five different strains which were almost completely inhibited by the extract. Furthermore, it significantly decreased growth rate and maximum growth of all tested strains. In vivo trials, confirmed a strong antibacterial activity of the extract that significantly reduced the bacterial load on fresh-cut apple, melon and pear and maintained the population at low levels throughout the storage period (7 days). PGE at 12 g/l reduced L. monocytogenes by 1.24, 1.89, and 0.91 log units soon after treatment and by 3.81, 1.53, and 2.99 log units, after 7 days of storage on apple, pear and melon, respectively. This high antibacterial activity could be mainly related to the high content of polyphenols (ellagitannins) in the extract. Overall, results of this study suggest a potential industrial application of PGE to reduce the growth of the pathogenic microorganisms in fresh-cut fruit and ensure a microbial safety in case of contamination.