Department of Food Science and Technology, University of Tennessee-Knoxville, Knoxville, TN 37996-4591, USA.
J Food Prot. 2012 Apr;75(4):753-7. doi: 10.4315/0362-028X.JFP-11-214.
Ilex paraguariensis is popularly used in the preparation of a tea infusion (yerba mate), most commonly produced and consumed in the South American countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, aqueous extracts of commercial tea, derived from the holly plant species I. paraguariensis were evaluated for their ability to inhibit or inactivate Escherichia coli O157:H7 in a microbiological medium and modified apple juice. Dialyzed, lyophilized aqueous extracts were screened for antimicrobial activity against E. coli O157:H7 strains ATCC 43894 and 'Cider' in tryptic soy broth (TSB) and apple juice (adjusted to pH 6.0 to allow for growth of the bacterium). A mixture of the two strains was used as the inoculum when apple juice was used as the medium. MBCs were determined to be ca. 5 and 10 mg/ml for ATCC 43894 and 'Cider', respectively, in TSB. Higher concentrations of the extract were required to inactivate E. coli O157:H7 in pH-adjusted apple juice. An approximate 4.5-log reduction was observed for E. coli O157:H7 treated with 40 mg/ml extract. It was concluded that aqueous extracts from commercial yerba mate have potential to be used as antimicrobials in foods and beverages against pathogenic E. coli O157:H7.
巴拉圭冬青广泛用于制备茶浸液（马黛茶），这种茶在乌拉圭、巴拉圭、阿根廷和巴西等南美国家最为常见。在这项研究中，评估了从冬青植物物种 I. paraguariensis 获得的商业茶的水提取物抑制或失活大肠杆菌 O157:H7 的能力，该提取物在微生物培养基和改良的苹果汁中使用。对透析、冻干的水提取物进行了针对大肠杆菌 O157:H7 菌株 ATCC 43894 和“Cider”的抗微生物活性筛选，在胰蛋白酶大豆肉汤（TSB）和苹果汁（调整 pH 值至 6.0 以允许细菌生长）中。当使用苹果汁作为培养基时，使用两种菌株的混合物作为接种物。在 TSB 中，对于 ATCC 43894 和“Cider”，MBC 分别约为 5 和 10 mg/ml。需要更高浓度的提取物才能在 pH 调整的苹果汁中失活大肠杆菌 O157:H7。用 40 mg/ml 提取物处理的大肠杆菌 O157:H7 观察到约 4.5 个对数减少。因此，商业马黛茶的水提取物具有作为食品和饮料中针对致病性大肠杆菌 O157:H7 的抗菌剂的潜力。
