Reduction of the attachment, survival and growth of L. monocytogenes on lettuce leaves by UV-C stress

Abstract

Mild stress of leafy greens by UV-C radiation has been reported to stimulate plant defences capable of reducing pathogens on produce surfaces. In this study, the attachment, survival and growth of Listeria monocytogenes was investigated on lettuces stressed with mild UV-C radiation (1.3 and 2.6 kJm−2). Attachment of L. monocytogenes to UV-C stressed (1.3 kJm−2) lettuce leaves after 1 h was significantly (p < 0.05) reduced by 1.4–1.5 log cfu/cm2. UV-C stress also reduced the survival of L. monocytogenes on lettuce by 1.8–1.9 log cfu/g 96 h after inoculation, however a higher dosage of UV-C stress (2.6 kJm−2) did not inhibit the survival of L. monocytogenes. The total phenolic compounds in lettuce significantly increased following UV-C stress (1.3 kJm−2) indicating the accumulation of polyphenols might have contributed to the inhibition of L. monocytogenes attachment and growth. Appropriate dosage of mild UV-C stress of lettuce can reduce the attachment, survival and growth of L. monocytogenes in lettuce and can therefore be explored further for application in fresh produce safety.