Fate of Salmonella typhimurium and Staphylococcus aureus in Meat Salads Prepared with Mayonnaise

Staphylococcus aureus and Salmonella typhimurium were tested for their ability to survive and to multiply in meat salads prepared with different concentrations of mayonnaise and held at 4, 22, and 32 C. When mayonnaise was added to meat salads in amounts recommended by recipes from a reputable cookbook, it inactivated a substantial portion of the initial population of both S. aureus (30-60%) and S. typhimurium (20-25%). Salads that were refrigerated at 4 C for 24 h evidenced very little growth of either organism whether mayonnaise was present or not. Storing salads at 22 or 32 C for 5 h resulted in <1.0 log₁₀ increase of either organism with the greatest increase occurring in salads containing no mayonnaise. Mayonnaise retarded but did not prevent the growth of S. aureus or S. typhimurium in salads stored at 22 or 32 C for 24 h. Increasing the concentration of mayonnaise in salads increased the degree to which growth of these organisms was delayed. Contrary to popular belief, the presence of mayonnaise in meat salads tends to retard rather than enhance growth of food-borne pathogens. However, addition of mayonnaise should not be considered a substitute for refrigeration for preserving meat salads from the growth of food-borne pathogens.