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 post-processing contamination by Listeria monocytogenes. The efficacy of UV in combination with citric acid (CA; 0.2 and 0.5%), dimethyl dicarbonate (DMDC; 250 and 500 ppm) or hydrogen peroxide (2,000 and 4,000 ppm) 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 60 min 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