Influence of Temperature of Incubation on Staphylococcus aureus Growth and Enterotoxin Production in Homemade Mayonnaise.

Homemade mayonnaise, in which pH had been adjusted to a range between 5.0 and 5.8 by the addition of vinegar, was inoculated with eight Staphylococcus aureus strains known to be enterotoxigenic. They were incubated for a maximum of 7 days at 22, 28, 37, and 44°C. Periodically, staphylococcal growth and pH were determined. Mayonnaise samples were examined on d 7 for the presence of enterotoxins A, B, C, and D. Staphylococcal growth was higher at 22°C (average log 7.21 cfu/g), than at the other temperatures tested (log 7.15, 6.77, and 5.93 cfu/g, respectively for 28, 37, and 44°C), suggesting a better growth in mayonnaise at low room temperature. Enterotoxin synthesis took place mainly at 28°C, as 33.3% of the total enterotoxins produced were detected at this temperature. However, some strains synthesized high amounts of enterotoxin even at 22°C.