To apply UV-C as a non-heating sterilization method to increase the microbiological safety of fresh seedless watermelon products, reductions in E. coli and quality changes by treatment dose (0, 2, 4, 8, 14, 20 kJ/m2) were investigated. The pH, sugar content, and hardness of watermelon inoculated with E. coli were not significantly different according to the UV-C treatment dose, but the polyphenol content was significantly decreased compared to the controls (425.4 GAE μg/g F.W.). When treated with 2 and 4 kJ/m2, the lycopene content was 31.6 and 30.9 μg/g F.W., respectively, which was increased compared to the controls (28.5 μg/g F.W.). The arginine and citrulline content was also significantly increased compared to the controls. The number of E. coli was significantly decreased compared to the controls following UV-C treatment. Considering the degree of E. coli reduction, lycopene content, arginine content, citrulline content, and UV-C irradiation time, subsequent experiments were conducted by selecting a UV-C treatment dose of 2 kJ/m2. The results of confirming the degree of reduction in the number of E. coli colonies by a single treatment and combined treatment with UV-C 2 kJ/m2 and 70% ethanol showed that the combined treatment was most effective as colonies were decreased by 2.3 log CFU/g compared to the controls. Therefore, it is judged that UV-C 2 kJ/m2 radiation and combined treatment with 70% ethanol could be applied as a non-heating sterilization method for fresh watermelon slices.

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