Scollard Johann, Francis Gillian A, O'Beirne David
Food Science Research Centre, Department of Life Sciences, University of Limerick, Limerick, Ireland.
J Food Prot. 2009 Jun;72(6):1209-15. doi: 10.4315/0362-028x-72.6.1209.
Natural antimicrobials such as plant essential oils (EOs) may be useful for controlling pathogenic bacteria on fresh-cut vegetables. The antilisterial properties of EOs (thyme, oregano, and rosemary), in combination with different storage atmospheres (air, 5% CO2-2% O2-93% N2, and 20% CO2-1% O2-79% N2) and temperatures (4 and 80C), were examined using a gas flow-through system combined with a vegetable agar model. The antimicrobial effects of the EOs varied depending on the oil, the Listeria strain and species, the method of application, and the storage conditions tested. Using the disk diffusion assay, the antilisterial effectiveness of the oils was in the following order: thyme EO > oregano EO > rosemary EO. Volatiles released from the EOs resulted in very small antilisterial effects, indicating that the oils needed to be in direct contact with cultures in order to be effective. There were strain and species effects, with L. innocua NCTC 11288 exhibiting the strongest resistance to EOs, and L. monocytogenes NCTC 7973 being the most sensitive strain. In addition, the effectiveness of the EOs was influenced by storage atmosphere and temperature. Use of EOs in combination with a gas atmosphere of 20% CO2-1% O2-79% N2 had the greatest antilisterial effect, suggesting that high CO2 atmospheres enhanced the antilisterial properties of EOs. Lowering the storage temperature from 8 to 4OC improved the antilisterial activity of thyme oil. It is concluded that thyme and oregano EOs display strong inhibitory effects against Listeria and that increasing CO2 levels and lowering storage temperatures further enhance these antilisterial effects.
天然抗菌剂如植物精油（EOs）可能有助于控制鲜切蔬菜上的病原菌。使用气流通过系统结合蔬菜琼脂模型，研究了EOs（百里香、牛至和迷迭香）的抗李斯特菌特性，以及不同的储存气氛（空气、5%二氧化碳-2%氧气-93%氮气和20%二氧化碳-1%氧气-79%氮气）和温度（4和8℃）的影响。EOs的抗菌效果因油的种类、李斯特菌菌株和种类、应用方法以及测试的储存条件而异。使用纸片扩散法，油的抗李斯特菌有效性顺序如下：百里香EO＞牛至EO＞迷迭香EO。EOs释放的挥发物产生的抗李斯特菌效果非常小，这表明油需要与培养物直接接触才能有效。存在菌株和种类效应，无害李斯特菌NCTC 11288对EOs表现出最强的抗性，而单核细胞增生李斯特菌NCTC 7973是最敏感的菌株。此外，EOs的有效性受储存气氛和温度的影响。将EOs与20%二氧化碳-1%氧气-79%氮气的气体气氛结合使用具有最大的抗李斯特菌效果，这表明高二氧化碳气氛增强了EOs的抗李斯特菌特性。将储存温度从8℃降至4℃提高了百里香油的抗李斯特菌活性。得出的结论是，百里香和牛至EOs对李斯特菌显示出强烈的抑制作用，增加二氧化碳水平和降低储存温度进一步增强了这些抗李斯特菌效果。
