Selma María Victoria, Beltrán David, Allende Ana, Chacón-Vera Eliseo, Gil María Isabel
Research Group on Quality, Safety and Bioactivity of Plant Foods, Food Science and Technology Department, CEBAS-CSIC, P.O. Box 164, Espinardo, Murcia, E-30100, Spain.
Food Microbiol. 2007 Aug;24(5):492-9. doi: 10.1016/j.fm.2006.09.005. Epub 2006 Nov 13.
Several outbreaks of shigellosis have been attributed to the consumption of contaminated fresh-cut vegetables. The minimal processing of these products make it difficult to ensure that fresh produce is safe for consumer. Chlorine-based agents have been often used to sanitize produce and reduce microbial populations in water applied during processing operations. However, the limited efficacy of chlorine-based agents and the production of chlorinated organic compounds with potential carcinogenic action have created the need to investigate the effectiveness of new decontamination techniques. In this study, the ability of ozone to inactivate S. sonnei inoculated on shredded lettuce and in water was evaluated. Furthermore, several disinfection kinetic models were considered to predict S. sonnei inactivation with ozone. Treatments with ozone (1.6 and 2.2 ppm) for 1 min decreased S. sonnei population in water by 3.7 and 5.6 log cfu mL(-1), respectively. Additionally, it was found that S. sonnei growth in nutrient broth was affected by ozone treatments. After 5.4 ppm ozone dose, lag-phases were longer for injured cells recovered at 10 degrees C than 37 degrees C. Furthermore, treated cells recovered in nutrient broth at 10 degrees C were unable to grow after 16.5 ppm ozone dose. Finally, after 5 min, S. sonnei counts were reduced by 0.9 and 1.4 log units in those shredded lettuce samples washed with 2 ppm of ozonated water with or without UV-C activation, respectively. In addition, S. sonnei counts were reduced by 1.8 log units in lettuce treated with 5 ppm for 5 min. Therefore, ozone can be an alternative treatment to chlorine for disinfection of wash water and for reduction of microbial population on fresh produce due to it decomposes to nontoxic products.
几起志贺氏菌病的爆发被归因于食用了受污染的鲜切蔬菜。这些产品的加工过程极为有限，难以确保新鲜农产品对消费者来说是安全的。氯基消毒剂常被用于对农产品进行消毒，并减少加工过程中使用的水中的微生物数量。然而，氯基消毒剂的效果有限，且会产生具有潜在致癌作用的氯代有机化合物，因此有必要研究新的去污技术的有效性。在本研究中，评估了臭氧对接种在切丝生菜上以及水中的宋内志贺氏菌的灭活能力。此外，还考虑了几种消毒动力学模型来预测臭氧对宋内志贺氏菌的灭活情况。用臭氧（1.6和2.2 ppm）处理1分钟，分别使水中的宋内志贺氏菌数量减少了3.7和5.6 log cfu mL(-1)。此外，还发现臭氧处理会影响宋内志贺氏菌在营养肉汤中的生长。在5.4 ppm臭氧剂量处理后，在10℃下复苏的受损细胞的延迟期比在37℃下更长。此外，在10℃下于营养肉汤中复苏的处理过的细胞在16.5 ppm臭氧剂量处理后无法生长。最后，5分钟后，用2 ppm含或不含UV-C活化的臭氧水冲洗的切丝生菜样品中，宋内志贺氏菌数量分别减少了0.9和1.4 log单位。此外，用5 ppm处理5分钟的生菜中，宋内志贺氏菌数量减少了1.8 log单位。因此，由于臭氧可分解为无毒产物，它可作为氯的替代处理方法，用于洗涤水消毒以及减少新鲜农产品上的微生物数量。
