Guo Shuanghuan, Huang Runze, Chen Haiqiang
Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716-2150, USA.
Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716-2150, USA.
Int J Food Microbiol. 2017 Sep 18;257:101-109. doi: 10.1016/j.ijfoodmicro.2017.06.017. Epub 2017 Jun 19.
With the demand for fresh produce increases in recent decades, concerns for microbiological safety of fresh produce are also raised. To identify effective ultraviolet (UV) light treatment for fresh produce decontamination, we first determined the effect of three forms of UV treatment, dry UV (samples were treated by UV directly), wet UV (samples were dipped in water briefly and then exposed to UV), and water-assisted UV (samples were treated by UV while being immersed in agitated water) on inactivation of Salmonella inoculated on tomatoes and fresh-cut lettuce. In general, the water-assisted UV treatment was found to be the most effective for both produce items. Chlorine and hydrogen peroxide were then tested to determine whether they could be used to enhance the decontamination efficacy of water-assisted UV treatment and prevent transfer of Salmonella via wash water by completely eliminating it. Neither of them significantly enhanced water-assisted UV inactivation of Salmonella on tomatoes. Chlorine significantly improved the decontamination effectiveness of the water-assisted UV treatment for baby-cut carrots and lettuce, but not for spinach. In general, the single water-assisted UV treatment and the combined treatment of water-assisted UV and chlorine were similar or more effective than the chlorine washing treatment. In most of the cases, no Salmonella was detected in the wash water when the single water-assisted UV treatment was used to decontaminate tomatoes. In a few cases when Salmonella was detected in the wash water, the populations were very low,≤2CFU/mL, and the wash water contained an extremely high level of organic load and soil level. Therefore, the single water-assisted UV treatment could potentially be used as an environmentally friendly and non-chemical alternative to chlorine washing for tomatoes after validation in industrial scale. For lettuce, spinach and baby-cut carrots, the combined treatment of water-assisted UV treatment and chlorine was needed to maintain a pathogen free environment in the wash water so that cross contamination could be prevented during fresh produce washing.
近几十年来，随着对新鲜农产品需求的增加，人们对新鲜农产品微生物安全的担忧也日益凸显。为了确定用于新鲜农产品去污的有效紫外线（UV）处理方法，我们首先测定了三种形式的紫外线处理对接种在番茄和鲜切生菜上的沙门氏菌的灭活效果，这三种处理分别是：干紫外线处理（样品直接用紫外线处理）、湿紫外线处理（样品先短暂浸入水中，然后再暴露于紫外线下）和水辅助紫外线处理（样品在搅拌的水中浸泡时用紫外线处理）。总体而言，发现水辅助紫外线处理对这两种农产品最为有效。随后测试了氯和过氧化氢，以确定它们是否可用于提高水辅助紫外线处理的去污效果，并通过完全消除沙门氏菌来防止其通过洗涤水转移。它们都没有显著增强水辅助紫外线对番茄上沙门氏菌的灭活效果。氯显著提高了水辅助紫外线处理对小胡萝卜和生菜的去污效果，但对菠菜无效。总体而言，单一的水辅助紫外线处理以及水辅助紫外线与氯的联合处理与氯洗涤处理效果相似或更有效。在大多数情况下，当使用单一的水辅助紫外线处理对番茄进行去污时，洗涤水中未检测到沙门氏菌。在少数情况下，洗涤水中检测到沙门氏菌时，其数量非常低，≤2CFU/mL，且洗涤水中含有极高水平的有机负荷和土壤含量。因此，在经过工业规模验证后，单一的水辅助紫外线处理有可能作为一种环保且无化学物质的替代方法用于番茄的氯洗涤。对于生菜、菠菜和小胡萝卜，需要采用水辅助紫外线处理与氯的联合处理，以保持洗涤水中无病原体环境，从而在新鲜农产品洗涤过程中防止交叉污染。
