This study was conducted to investigate the effect of cold plasma combined with UV-C irradiation against Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes on lettuce. E. coli O157:H7, S. Typhimurium, and L. monocytogenes, corresponding to approximately 5.82, 5.09, 5.65 log CFU/ g, were inoculated on lettuce, respectively. Then, the lettuce was treated with cold plasma, UV-C and combination (cold plasma + UV-C), respectively. The treated lettuce was stored for 9 days at 4oC for microbiological analysis and sensory evaluation. Cold plasma reduced the populations of E. coli O157:H7, S. Typhimurium, and L. monocytogenes by 0.26, 0.65, and 0.93 log CFU/g, respectively. Each microorganism were reduced by 0.87, 0.88, and 1.14 log CFU/ g after UV-C treatment. And, the combined treatment that was treated by cold plasma after UV-C treatment reduced the populations of inoculated microorganisms by 1.44, 2.70, 1.62 log CFU/g, respectively. The all treatment significantly (p < 0.05) reduced the populations of all inoculated bacteria compared to untreated lettuce. UV-C combined with cold plasma was the most effective for reducing the pathogenic bacteria on lettuce, by showing log-reductions of ≥ 2.0 log CFU/g. All treatment was not significantly different until 6 day storage compared to control group in terms of appearance, texture and overall acceptability. Therefore, the combined treatment will be an effective intervention method to control the bacteria on lettuce.

In order to estimate the UV-A ray line 's cut rate and sensitivity in color lens, it was measured the light transmittance in the 320-700 nm wavelength regions. W e obtained the area to integrate the light transmittance of standard lens and sample in the 320-400 nm wavelength regions and established a, ~ of UV-A line' s cut efficiency by contrast its area. The Eye sensitivity in the difference conditions of a light source intensity consists of two functions by the receptor of cone and rod according to a wavelength. Transmission light which permeate depends on absorption wavelength, and relationship of final luminous efficiency' s estimation method is expressed by multiplication of luminous efficiency and transmittance intensity of lens. P/ = T(A) · P(A) About R · Y · G · B color, applied photopic and scotopic that is luminous efficiency