Raybaudi-Massilia Rosa M, Mosqueda-Melgar Jonathan, Martín-Belloso Olga
Department of Food Technology, University of Lleida, UTPV-CeRTA, Avenida Alcalde Rovira, Roure, 191, 25198 Lleida, Spain.
J Food Prot. 2006 Jul;69(7):1579-86. doi: 10.4315/0362-028x-69.7.1579.
The antimicrobial properties of essential oils (EOs) and their derivatives have been known for years. However, the information published about the minimal effective concentration of EOs against microorganisms in fruit juices is scarce. In this study, both MIC and MBC of six EOs (lemongrass, cinnamon, geraniol, palmarosa, or benzaldehyde) against Salmonella Enteritidis, Escherichia coli, and Listeria innocua were determined by the agar and broth dilution methods, respectively. All of the six EOs inhibited the microbial (Salmonella Enteritidis, E. coli, and L. innocua) growth at a concentration from 1 microl/ ml (MIC). These studies led to choosing the three most effective EOs. Lemongrass, cinnamon, and geraniol were found to be most effective in inhibiting the growth of the microorganisms and thus were used for the MBC analysis. On this last point, significant differences (P < 0.05) among EOs, their concentrations, and culture media (apple, pear, and melon juices, or tryptone soy broth medium) were found after comparing the results on MBC for each microorganism. A concentration of 2 microl/ml from lemongrass, cinnamon, or geraniol was enough to inactivate Salmonella Enteritidis, E. coli, and L. innocua in apple and pear juices. However, in melon juice and tryptone soy broth medium, concentrations of 8 and 10 microl/ml from cinnamon, respectively, or 6 microl/ml from geraniol were necessary to eliminate the three microorganisms, whereas lemongrass required only 5 micro/ml to inactivate them. These results suggest that EOs represent a good alternative to eliminate microorganisms that can be a hazard for the consumer in unpasteurized fruit juices. The present study contributes to the knowledge of MBC of EOs against pathogenic bacteria on fruit juices.
多年来，人们一直知晓香精油（EOs）及其衍生物具有抗菌特性。然而，关于香精油对果汁中微生物的最低有效浓度的公开信息却很匮乏。在本研究中，分别通过琼脂稀释法和肉汤稀释法测定了六种香精油（柠檬草、肉桂、香叶醇、玫瑰草或苯甲醛）对肠炎沙门氏菌、大肠杆菌和无害李斯特菌的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。所有六种香精油在浓度为1微升/毫升（MIC）时均能抑制微生物（肠炎沙门氏菌、大肠杆菌和无害李斯特菌）的生长。这些研究促使选择了三种最有效的香精油。结果发现柠檬草、肉桂和香叶醇在抑制微生物生长方面最为有效，因此被用于MBC分析。在这最后一点上，比较每种微生物的MBC结果后发现，香精油、其浓度以及培养基（苹果汁、梨汁和甜瓜汁或胰蛋白胨大豆肉汤培养基）之间存在显著差异（P < 0.05）。柠檬草、肉桂或香叶醇浓度为2微升/毫升时足以使苹果汁和梨汁中的肠炎沙门氏菌、大肠杆菌和无害李斯特菌失活。然而，在甜瓜汁和胰蛋白胨大豆肉汤培养基中，分别需要肉桂浓度为8微升/毫升和10微升/毫升，或香叶醇浓度为6微升/毫升才能消除这三种微生物，而柠檬草仅需5微升/毫升就能使其失活。这些结果表明，香精油是消除未杀菌果汁中可能对消费者构成危害的微生物的良好替代品。本研究有助于了解香精油对果汁中致病菌的MBC。
