Mayonnaise, Sandwiches and Salmonella

Sandwiches, prepared with home-cooked or commercially purchased turkey meat and made with or without commercially available mayonnaise, were inoculated with approximately 600-700 cells of a nalidixic acid-resistant strain of Salmonella typhimurium per gram of each sandwich. The sandwiches were incubated at 4, 21, and 30 C and samples analyzed at 4, 8 and 24 h for the number of S. typhimurium cells. Significant increases in the number of S. typhimurium cells were found in sandwiches prepared without mayonnaise and containing home cooked turkey meat after 8 h of incubation at 30 C and 24 h of incubation at 21 or 30 C. The increase in numbers of S. typhimurium in sandwiches prepared with commercially processed turkey meat was significantly lower than the increase in sandwiches prepared with home-cooked turkey meat. Mayonnaise had a significant inhibitory effect on growth of S. typhimurium in sandwiches prepared with turkey breast meat; however, mayonnaise did not prevent Salmonella from multiplying when the sandwiches were stored at 21 or 30 C for 8 or 24 h.