Internet Journal of Food Safety, no.8, pp.7-13, 2006 (Peer-Reviewed Journal)
The amtimicrobial effect of oregano tea (1/10, w/v, in distilled water), commercial oregano water, and 1⁄2 oregano water (1/1, commercial oregano water/distilled water, v/v) against Escherichia coli O157:H7, Listeria monocytogenes 4b, Staphylococcus aureus and Yersinia enterocolitica 03 after direct contact at 20 ±2 C for 1, 10, 30, and 60 min were comparatively evaluated. The Plate Count Agar was used for colony counts and the content of each treatment tube was enriched in Brain Heart Infusion broth after the 60 min direct contact period. All the four pathogens in oregano water and 1⁄2 oregano water decreased to uncountable level (1 CFU/ml) in one min. No growth has also occured in enrichments. Oregano tea was less effective than the oregano waters after 1 min, but counts of E. coli O157:H7, L. monocytogenes 4b, S. aureus and Y. enterocolitica 03 decrease to uncountable level after 60, 60, 10, and 10 min treatment periods, respectively. All the four test pathogens demonstrated grow ability in enrichment broth after a 60 min treatment period in oregano tea. E. coli O157:H7 appeared to be the most resistant pathogen followed by L. monocytogenes 4b, S. aureus and Y. enterocolitica, respectively. The use of water extracts or hydrosol of oregano for the decontamination or disinfection in food safety strategies should be evaluated in comparison with other natural antimicrobial spices.