Effects of Oregano Extract on the Inhibition of Selected Pathogens in Raw Beef Meat

Abstract

<strong>Introduction:</strong> <em>Listeria monocytogenes</em>, <em>Salmonella </em>spp. and <em>Staphylococcus aureus </em>have been found in raw meat and meat products. The present study aimed to evaluate the effects of oregano extract(OE) at the concentrations of 0.1%, 0.2%, and 0.5%against <em>Listeria monocytogenes, Salmonella typhimurium</em>, and <em>Staphylococcus aureus </em>in raw beef meat during refrigerated storage (4±1ºC) for 10 days. <strong>Methods:</strong> In this study, 10 grams of raw beef meat were added to 90 milliliters of sterile buffered peptone water and homogenized in a stomacher for two minutes. Proper decimal dilutions were prepared in buffered peptone water for microbial enumeration. <em>S. typhimurium </em>was cultured on Salmonella Shigella agar and incubated at the temperature of 37ºC for 24 hours. In addition, <em>L. monocytogenes</em> was cultured on PALCAM listeria-selective agar and incubated at the temperature of 30ºC for 48 hours, and <em>S. aureus </em>was cultured on Baird-Parker agar and incubated at the temperature of 37ºC for 48 hours. <strong>Results:</strong> In all the experiments, no growth was observed in <em>L. monocytogenes,</em> <em>S. typhimurium</em>, and <em>S. aureus </em>in the non-inoculated control samples. Antimicrobial effects were more significant at the higher concentrations of OE (P<0.05). Moreover, the addition of OEs to raw beef meat decreased the microbial counts of the tested pathogens during storage (P<0.05). <strong>Conclusion:</strong> According to the results, utilization of OE in raw beef meat may be an effectivestrategy to assure safety against<em> L. monocytogenes,</em> <em>S. typhimurium</em>, and <em>S. aureus</em>. However, the associated sensory limitations do not allow the use of OE at higher concentrations, which are more effective in pathogen inhibition.