Effects of UV irradiation on selected pathogens in peptone water and on stainless steel and chicken meat

Effects of intensity and processing time of 254 nm UV irradiation on Listeria monocytogenes, Escherichia coli O157:H7. and Salmonella Typhimurium were investigated. Intensities measured at 5.08, 10.1. 15.2. and 20.3 cm from the light source were 1,000, 500. 250, and 150 muW/cm(2). respectively. Intensities of 250 or 500 muW/cm(2) reduced all suspended pathogen cells in peptone water about 5 log cycles after 2 min and completely inactivated L. monocytogenes and E. coli O157:H7 after 3 min by reductions of 8.39 and 8.64 log cycles. respectively. Intensities of 250 or 500 muW/cm(2) also reduced (P less than or equal to 0.05) the tested pathogens inoculated on stainless steel (SS) chips. and E. coli O157:H7 was completely destroyed at 500 muW/cm(2) for 3 min. After UV treatment for 3 min at 500 muW/cm(2). all selected pathogens on chicken meat with or without skin showed reduction ranges from 0.36 to 1.28 log cycles. Results demonstrated that UV irradiation could effectively decrease pathogens in peptone water and on SS but that it was less effective on chicken meat.