title: Inactivation of Listeria monocytogenes on Frozen Red Raspberries by Using UV-C Light.
abstract: In this study, the efficacy of UV-C treatment was determined on the reduction of foodborne pathogens on artificially contaminated frozen food surfaces. At first, the UV-C inactivation rates on 100 μl of the respective cocktails of Escherichia coli O157:H7, Salmonella , and Listeria monocytogenes covered underneath 0.5-cm-thick ice were examined. Simultaneously, the energy percentage of UV-C transmitted through the ice was determined. The experiments showed that more than 65% of the UV-C light energy passed through the ice and that UV-C susceptibility was in the descending order of E. coli O157:H7, Salmonella , and L. monocytogenes . L. monocytogenes , the most UV-C-resistant strain, was then selected to test on frozen raspberries. The UV-C inactivation kinetic data of L. monocytogenes were well described using the Weibull equation. During 720 s of UV-C exposure, with a total dose of 7.8 × 102mJ/cm2, a 1.5-log CFU/g reduction of L. monocytogenes population on the surface of frozen red raspberries was noted. No significant differences in total anthocyanins, total phenolics, and total antioxidant activity were observed between UV-C-treated and untreated frozen berries immediately after treatment. At the end of 9 months of storage at -35°C, UV-C-treated berries had statistically lower total phenolics, higher total anthocyanins, and similar total antioxidant activity compared with untreated berries. This study shows that UV-C light can be used to reduce the L. monocytogenes population on frozen raspberries.
authors.affiliation: School of Food Science, Washington State University, P.O. Box 646376, Pullman, Washington 99164-6376, USA.
authors.forename: Yen-Te
authors.initials: YT
authors.lastname: Liao
authors.affiliation: Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5.
authors.forename: Roopesh M
authors.initials: RM
authors.lastname: Syamaladevi
authors.affiliation: Biological Systems Engineering, Washington State University, P.O. Box 646376, Pullman, Washington 99164-6376, USA.
authors.forename: Hongchao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Food Science, Washington State University, P.O. Box 646376, Pullman, Washington 99164-6376, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Killinger
authors.affiliation: Biological Systems Engineering, Washington State University, P.O. Box 646376, Pullman, Washington 99164-6376, USA.
authors.forename: Shyam
authors.initials: S
authors.lastname: Sablani
mesh_terms: D015169:Colony Count, Microbial; D019453:Escherichia coli O157; D005516:Food Microbiology; D008089:Listeria monocytogenes; D065856:Rubus
keywords: Antioxidant activity; Escherichia coli O157:H7; Listeria monocytogenes; Salmonella; UV-C transparency of ice