Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Republic of Korea.
Int J Food Microbiol. 2013 Sep 16;166(3):349-55. doi: 10.1016/j.ijfoodmicro.2013.08.010. Epub 2013 Aug 18.
The effect of various conditions on inactivation of foodborne pathogens and quality of fresh-cut lettuce during ultraviolet (254 nm, UVC) radiation was investigated. Lettuce was inoculated with a cocktail of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and treated at different temperatures (4 and 25 °C), distances between sample and lamp (10 and 50 cm), type of exposure (illuminated from one or two sides), UV intensities (1.36 to 6.80 mW/cm²), and exposure times (0.5 to 10 min), sequentially. UV treatment at 25 °C for 1 min achieved 1.45-, 1.35-, and 2.12-log reductions in surface-inoculated E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, whereas the reduction of these pathogens at 4 °C was 0.31, 0.57, and 1.16 log, respectively. UV radiation was most effective when distance from UV lamp to the sample was minimal (10 cm) and radiation area was maximal (two-sided exposure). All UV intensities significantly (P<0.05) reduced the three pathogens after 10 min exposure, but the effect of treatment was correlated with UV intensity and exposure time. Color values and texture parameters of lettuce subjected to UV treatment under the optimum conditions (25 °C, 10 cm between sample and lamp, two-sided exposure, 6.80 mW/cm²) were not significantly (P>0.05) different from those of nontreated samples up to 5 min exposure. However, these qualities significantly (P<0.05) changed at prolonged treatment time. These results suggest that UV radiation under optimized conditions could reduce foodborne pathogens without adversely affecting color quality properties of fresh-cut lettuce.
研究了不同条件对经紫外线（254nm，UVC）辐射处理的食源性病原菌失活和鲜切生菜品质的影响。将大肠杆菌 O157:H7、肠炎沙门氏菌和单增李斯特菌的混合物接种到生菜上，并在不同温度（4°C 和 25°C）、样品与灯之间的距离（10cm 和 50cm）、暴露类型（单面或双面照射）、紫外线强度（1.36 至 6.80mW/cm²）和暴露时间（0.5 至 10 分钟）下进行处理。在 25°C 下处理 1 分钟，可使表面接种的大肠杆菌 O157:H7、肠炎沙门氏菌和单增李斯特菌分别减少 1.45、1.35 和 2.12 个对数，而在 4°C 下，这些病原菌的减少量分别为 0.31、0.57 和 1.16 个对数。当紫外线灯与样品之间的距离最小（10cm）且辐射面积最大（双面照射）时，紫外线辐射最为有效。所有紫外线强度在 10 分钟暴露后均显著（P<0.05）降低了三种病原菌，但处理效果与紫外线强度和暴露时间相关。在最佳条件（25°C、样品与灯之间的距离为 10cm、双面照射、6.80mW/cm²）下，经紫外线处理的生菜的颜色值和质地参数在 5 分钟暴露内与未经处理的样品无显著差异（P>0.05）。然而，这些品质在延长的处理时间内会显著变化（P<0.05）。这些结果表明，在优化条件下的紫外线辐射可以减少食源性病原菌，而不会对鲜切生菜的颜色质量特性产生不利影响。
