Preliminary Investigation of the Effect of Chemical Sanitizers and UV-C Light on Listeria monocytogenes Biofilm Survivability

Abstract

The ability of Listeria monocytogenes to adapt under different environments and form biofilms is a challenge for food safety. Mature biofilms are difficult to disrupt. Chemical sanitizers combined with nonthermal technologies might be an effective way to control L. monocytogenes biofilms. This study was conducted to investigate L.monocytogenes biofilm survival after treatments withchemical sanitizers and UV-C light alone or in combination. A Centers for Diseases Control and Preventionbiofilm reactor was used to grow 4-day-old multistrainL.monocytogenes biofilms on stainless steel. Biofilmsurvival was evaluated after 10 min of exposure tolactic acid (4%), peroxy acid (100 ppm), and quaternaryammonium (400 ppm) alone or in combination with 15 or30 min of exposure to UV-C light (254 nm). The sequential treatment effect was also evaluated. Reductions of2.6 to 3.6 log CFU/cm2 were observed with chemicalsanitizers, whereas a maximum of 1.8 log CFU/cm2reduction was recorded after UV-C treatment. Combinedtreatments had an enhanced effect, and the sequence ofantimicrobial treatments was significant for lactic acid and peroxy acid (P < 0.05). The results obtained in this research offer an initial understanding of the response of L.monocytogenes biofilm to chemical sanitizers and contribute to development of effective strategies to controlthis pathogen in the food processing environment.