Abstract
The inhibitory effect of clove (Eugenia caryophyllata Thumb) on the growth of Escherichia coli 0157:H7 was determined. Tryptic soy broth (TSB) containing 0∼0.5% (w/v) of clove was inoculated with 10/sup/5∼10/sup/7 CFU/ml of E. coli and incubated at 5 different temperature (35, 5, -20, 50 and $55^{\circ}C$). The growth of E. coli was not inhibited at 0.1% clove and growth occured at 0.3% after a prolonged lag period while viable cells of E. coli decreased at 0.5% clove during storage at $35^{\circ}C$. During 32 days of refrigerated storage at $5^{\circ}C$, survivors of E. coli were decreased with the progress of time and increasing clove concentration. At the presence of 0.3 or 0.4% clove, bacterial cells were dead at the end of refrigerated storage. During frozen storage at -$20^{\circ}C$, survivors of E. coli at the presence of 0∼0.4% clove were decreased 2.9∼4.07 log cycles for 4 days of early period and then decreased 1.0∼2.1 log cycles through the frozen storage. There were small changes in populations of E. coli in TSB between different concentrations of clove during frozen storage. The D-values for E. coli at $50^{\circ}C$ were 105.26, 22.47, 13.76, 11.14 and 10.17 min at clove 0, 0.1, 0.2, 0.3, 0.4%, respectively. The D-values for E. coli at $55^{\circ}C$ were 10.75, 8.95, 7.40, 5.96 and 4.96 min at clove 0, 0.1, 0.2, 0.3, 0.4%, respectively. Antibacterial activity of clove against E. coli was more effective at $50^{\circ}C$ than at $55^{\circ}C$.
저농도의 clove(0~0.5%, w/v)를 함유한 tryptic soy broth(TSB)에 E. coli 0157:H7을 $10^{*}$ 5-$10^{*}$ 7 cells/ml되게 접종하여 clove가 E. coli의 증식과 생존에 미치는 효과를 이 세균의 최적온도($35^{\circ}C$)와 저온(-20, $5^{\circ}C$) 및 고온(50, $55^{\circ}C$)에서 검토하였다. $35^{\circ}C$에서의 E. coli의 증식은 0.1%의 clove 농도에서 배양초기부터 빠른 속도로 종식하였으나 0.3%에서는 약간의 유도기를 거친 후에 증식이 시작되었고 0.5%에서는 저장기간 중생균수가 감소하였다. Clove를 함유한 TSB에 $10^{*}$ 6~$10^{*}$ 7 cells/ml가 되게 E. coli를 접종하여 32일간 저온저장(-20, $5^{\circ}C$)하였을 때 E. coli에 대한 생존억제는 냉장에서 clove의 농도가 높을수록, 저장기간이 길어질수록 뚜렷해졌으며 0.3%와 0.4%에서는 각각 저장 32일, 24일에 사멸하였다. -2$0^{\circ}C$에서 동결저장한 경우에는 저장초기의 4일간 2.9~4.07 log cycle의 급격한 감소를 나타내었으며 이후부터 32일간 저장하는 동안 1.0~2.1 log cycle 감소하였고 첨가한 clove의 농도차이 에 따른 생존억제효과는 약간의 차이 에 불과하였다. $50^{\circ}C$에 저장한 E. coli는 clove농도 0, 0.1, 0.2, 0.3, 0.4%에서 D-value는 각각 105.26, 22.47, 13.76, 11.14, 10.17분이었으며 $55^{\circ}C$에서 D-value는 clove의 농도 0, 0.1, 0.2, 0.3, 0.4%에서 각각 10.75, 8.95, 7.40, 5.96, 4.96분이었다. Clove에 의한 생존억제작용은 $55^{\circ}C$에 비하여 $50^{\circ}C$에서 뚜렷한 효과를 나타내었다.