Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8598, USA.
Int J Food Microbiol. 2011 Jun 30;147(3):157-61. doi: 10.1016/j.ijfoodmicro.2011.04.002. Epub 2011 Apr 13.
Numerous Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh lettuce. The development of effective and easily implemented wash treatment could reduce such incidents. The purpose of this study was to evaluate the addition of food-grade detergents to sanitizer solutions for inactivation of E. coli O157:H7 on Romaine lettuce. Freshly-cut leaves of Romaine lettuce were dip-inoculated to achieve a final cell concentration of 7.8±0.2 log CFU/g, air-dried for 2h, and stored overnight at 4 °C. Leaves were then washed for 2 min in an experimental short chain fatty acid formulation (SCFA) or in one of the following solutions with or without 0.2% dodecylbenzenesulfonic acid or 0.2% sodium 2-ethyl hexyl sulfate: 1) deionized water; 2) 100 ppm chlorine dioxide; 3) 100 ppm chlorine; and 4) 200 ppm chlorine. Following wash treatment, samples were blended in neutralizing buffer (1:3) and surface plated on the selective media CT-SMAC. The efficacy of wash treatments, with or without the detergents, in inactivating E. coli O157:H7 cells on lettuce leaves were not significantly different. The most effective wash solution was SCFA, which was capable of reducing E. coli O157:H7 populations by more than 5 log CFU/g. The rest of the wash treatments resulted in a population reduction of less than 1 log CFU/g. The effectiveness of SCFA surpasses that of other sanitizer treatments tested in this study and requires further research to optimize treatments to preserve lettuce quality. Conventional detergents did not enhance the efficacy of any of the wash treatments tested during this study.
许多大肠杆菌 O157:H7 爆发都与食用新鲜生菜有关。开发有效且易于实施的洗涤处理方法可以减少此类事件的发生。本研究的目的是评估在生菜上添加食品级洗涤剂对大肠杆菌 O157:H7 的消毒溶液的杀菌效果。将新鲜切好的生菜叶浸泡接种，使最终细胞浓度达到 7.8±0.2 log CFU/g，风干 2 小时，在 4°C 下过夜储存。然后，将叶片在实验性短链脂肪酸配方 (SCFA) 或以下溶液中洗涤 2 分钟，这些溶液中含有或不含有 0.2%十二烷基苯磺酸钠或 0.2%十二烷基硫酸钠：1) 去离子水；2) 100 ppm 二氧化氯；3) 100 ppm 氯气；和 4) 200 ppm 氯气。洗涤处理后，将样品在中和缓冲液（1:3）中混合，并在选择性培养基 CT-SMAC 上表面接种。含有或不含有洗涤剂的洗涤处理在生菜叶片上杀菌大肠杆菌 O157:H7 细胞的效果没有显著差异。最有效的洗涤液是 SCFA，它能够将大肠杆菌 O157:H7 的数量减少超过 5 log CFU/g。其余洗涤处理的杀菌效果不到 1 log CFU/g。SCFA 的有效性超过了本研究中测试的其他消毒剂处理方法，需要进一步研究以优化处理方法，同时保持生菜的质量。在本研究中，常规清洁剂并没有提高任何洗涤处理的效果。
