In situ evaluation of citric acid powder to control Listeria monocytogenes on floors in meat processing plants

Several guidelines for control of L monocytogenes in food processing environments recommend the addition of citric acid powder to floors. However, documentation of the effect of this advice on L. monocytogenes in the food industry is not available in scientific literature. In the current study, the effect of addition of citric acid powder to five floors and a floor gutter, where water was observed to accumulate, on the occurrence of L. monocytogenes and total bacterial numbers were tested in situ in two meat processing plants. Overall, starting with addition of citric acid lead to a reduction of L. monocytogenes positive floors from 59 % to 13 %. Listeria monocytogenes was eradicated from all floor areas, with the exception of a floor that was positive in three out of four samplings in the citric acid test period. The total bacterial counts were on average lower in the period with addition of citric acid than in the control period. In the current study it was shown that addition of citric acid powder to floors where water tend to accumulate, can be effective for control of L monocytogenes.