علیرضا یوسفی

Listeria monocytogenes is one of the most frequent foodborne bacteria that can be transmitted through dairy products. The demand for replacing chemical preservatives with natural compounds has increased recently. The aim of this study was to investigate the effect of Echinophora platyloba DC ethanolic extract on the survival of L. monocytogenes in Lighvan cheese during ripening time. Three concentrations of E. platyloba ethanolic extract (0, 0.5, 1 and 1.5%) were added to raw milk at the beginning of Lighvan cheese manufacture, and the population of L. monocytogenes was counted on days 15, 30, 60 and 90. Furthermore, the pH and salt concentration of Lighvan cheese were evaluated in these periods. The results showed that an increase in the concentration of ethanolic extract, as well as the ripening time of Lighvan cheese, resulted in a significant decrease (p<0.05) in the levels of L. monocytogenes (cfu/g). Moreover, the logarithm of the L. monocytogenes population (log cfu/g) was significantly decreased (p<0.05) as the concentration of the added ethanolic extract was enhanced over the ripening time, but no significant changes in pH and salt concentration were observed in Lighvan cheese (p>0.05). It was found that the optimal concentration of E. platyloba ethanolic extract for the complete inhibition of L. monocytogenes was 1-1.5% following 90 days of the ripening.