Firouzi R, Shekarforoush S S, Nazer A H K, Borumand Z, Jooyandeh A R
Department of Pathobiology, Shiraz University, Shiraz 71345-1731, Iran.
J Food Prot. 2007 Nov;70(11):2626-30. doi: 10.4315/0362-028x-70.11.2626.
The in vitro effects of plant essential oils (EOs) against pathogenic bacteria are well known, yet few studies have addressed the effects of these compounds against pathogens associated with ready-to-cook foods. Experiments were conducted to determine the effectiveness of oregano and nutmeg EOs on the growth and survival of Yersinia enterocolitica and Listeria monocytogenes in broth culture and in Iranian barbecued chicken. Ready-to-cook Iranian barbecued chicken was prepared according to the common practice with 1, 2, and 3 microl/g of oregano and nutmeg EOs. The test and control (without EOs) samples were inoculated with Y. enterocolitica and L. monocytogenes to a final concentration of 6 to 7 log CFU/g and stored at 3, 8, and 20 degrees C. Microorganisms were counted just before and at 24, 48, and 72 h after storage based on growth on Yersinia selective agar supplemented with cefsulodine, igrasan, and novobiocin and on Listeria selective agar supplemented with nalidixic acid and acriflavin. In the broth culture system, the nutmeg EO had a greater effect on L. monocytogenes (MIC = 0.20 nicrol/ml) than did the oregano EO (MIC = 0.26 microl/ml). However, the oregano EO had a greater effect on Y. enterocolitica (MIC = 0.16 microl/ml) than did the nutmeg EO (MIC = 0.25 microl/ml). In ready-to-cook Iranian barbecued chicken, the log CFU per gram of both bacteria after up to 72 h of incubation was not decreased significantly by various combinations of oregano and nutmeg EOs (1, 2, and 3 microl/g) and storage temperatures (3, 8, and 20 degrees C) when compared with control samples (without EOs). Although examination of spices in culture media can yield accurate microbiological data, without complementary tests in foods these data are of limited value for assessing food safety.
植物精油（EOs）对病原菌的体外作用是众所周知的，但很少有研究探讨这些化合物对即食食品相关病原菌的影响。进行实验以确定牛至和肉豆蔻精油对小肠结肠炎耶尔森菌和单核细胞增生李斯特菌在肉汤培养物和伊朗烤鸡中的生长和存活的有效性。按照常规做法，用1、2和3微升/克的牛至和肉豆蔻精油制备即食伊朗烤鸡。将小肠结肠炎耶尔森菌和单核细胞增生李斯特菌接种到测试样品和对照样品（不含精油）中，使其最终浓度达到6至7 log CFU/克，并在3、8和20摄氏度下储存。根据在补充了头孢磺啶、伊格拉桑和新生霉素的耶尔森菌选择性琼脂以及补充了萘啶酸和吖啶黄素的李斯特菌选择性琼脂上的生长情况，在储存前以及储存24、48和72小时后对微生物进行计数。在肉汤培养系统中，肉豆蔻精油对单核细胞增生李斯特菌（MIC = 0.20微升/毫升）的作用比对牛至精油（MIC = 0.26微升/毫升）的作用更大。然而，牛至精油对小肠结肠炎耶尔森菌（MIC = 0.16微升/毫升）的作用比对肉豆蔻精油（MIC = 0.25微升/毫升）的作用更大。在即食伊朗烤鸡中，与对照样品（不含精油）相比，牛至和肉豆蔻精油（1、2和3微升/克）的各种组合以及储存温度（3、8和20摄氏度）在长达72小时的培养后，每克两种细菌的log CFU没有显著降低。尽管在培养基中检测香料可以得出准确的微生物学数据，但如果没有在食品中进行补充试验，这些数据对于评估食品安全的价值有限。
