Concurrent use of ultraviolet light and citric acid, dimethyl dicarbonate or hydrogen peroxide to inactivate listeria monocytogenes in chill brine

Chill brine used during ready-to-eat meat processing is an important source of postprocessing contamination by Listeria monocytogenes. The efficacy of UV in combination with citric acid (CA; 0.2 and 0.5%), dimethyl dicarbonate (DMDC; 250 and 500ppm) or hydrogen peroxide (2,000 and 4,000ppm) was determined to reduce L.monocytogenes in chill brine to below detectable levels after enrichment. Fresh brine solution was inoculated with L.monocytogenes and exposed to UV and/or antimicrobial agent at -1C in a recirculating UV treatment unit. When L.monocytogenes was no longer detectable via direct plating on MOX, enrichment in brain-heart infusion broth was performed, and suspect colonies were confirmed using API Listeria. The combinations of UV+0.5% CA and UV+500-ppm DMDC were found to be the most effective, where L.monocytogenes was undetectable via enrichment at 45 and 60min of treatment, respectively. CA (0.5%) when used in the absence of UV resulted in nondetection of L.monocytogenes. However, the reduction rate was higher when UV was used concurrent with CA. This work indicates that combinations of UV and antimicrobials may be more effective than either of the treatments alone for the reduction of L.monocytogenes in fresh brines. PRACTICAL APPLICATIONS: This paper describes the use of UV light and antimicrobial agents to control L.monocytogenes in chilled brines used for product cooling in the ready-to-eat meat industry. The data include time of exposure to UV light and level of antimicrobial agent, which result in inactivation of the pathogen. These data may support industry efforts to validate the use of UV light and antimicrobial agents to control L.monocytogenes in recirculating chill brine systems.