Impact of food residue on recovery of Listeria monocytogenes and Salmonella Typhimurium from stainless steel surface

This study evaluated the impact of different food residues on the recovery of Listeria monocytogenes and Salmonella Typhimurium from stainless steel surfaces. Food residues tested include lettuce rinsate, blended lettuce, low-fat milk, and whole milk for Listeria monocytogenes, and powdered infant formula, all-purpose flour, and whole milk dairy powder for Salmonella Typhimurium. Bacterial suspensions were inoculated on stainless steel surfaces with or without food residues and held for different time periods. Significant differences (P < 0.0001) in Salmonella Typhimurium recovery were observed between the no food residue control and all food residues over 24 hours. For Listeria monocytogenes, minimal variability in recovery was observed among food residue types, with significant differences from the no food residue control (P < 0.05) observed after 24 hours. The study also found that surface sampling can spread Listeria monocytogenes and Salmonella Typhimurium on stainless steel surfaces, suggesting that food residue type may affect microbial recovery during environmental monitoring.