• Korean journal of food and cookery science
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• v.13 no.4
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• pp.440-447
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• 1997

The antibacterial effect of low concentrations of oregano (Origanum vulgare L.) in culture broth against Escherichia coli O157:H7 and Staphylococcus aureus 196E was tested at 35,5 and -20$^{\circ}C$. Tryptic soy broth (TSB) containing 0∼2% (w/v) of oregano was inoculated with 10$\^$6/∼10$\^$7/ CFU/$m\ell$ of E. coli or S. aureus and incubated at each temperature. The growth of E. coli was not inhibited at 0.1∼1.0% oregano and the growth occured at 2% oregano but only after a prolonged lag period. The death rate of E. coli after stationary phase was increased with increasing concentration of oregano in culture broth. The growth of S. aureus was inhibited with increasing concentration of oregano at 35$^{\circ}C$. Growth of S. aureus occured at the presence of 0.3∼0.5% oregano after a long lag period while the viability at 1.0∼2.0% was decreased during storage at 35$^{\circ}C$. During refrigerated storage at 5$^{\circ}C$, inhibition of E. coli or S. aureus was increased with the progress of time and increasing spice concentration. At the presence of 0.5∼2.0% oregano, E. coli and S. aureus were dead after 20 and 16 days of refrigerated storage, respectively. During frozen storage at -20$^{\circ}C$, the antibacterial activity of oregano against E. coli was increased with increasing storage time and spice concentration while the antibacterial activity against S. aureus was effective during the early period of storage, and no changes in the population of S. aureus occurred at different concentrations of oregano during frozen storage. Viable counts of E. coli were 1/3∼l/7 and S. aureus were 1/18∼l/46 of the control at 0.1% oregano in culture broth during frozen storage.