Growth and Enterotoxin Production by Staphylococci in Genoa Salami ¹

Staphylococcus aureus strains 265 and 243 which produce enterotoxins A and B, respectively, were inoculated into meat being made into Genoa salami in the amount of 10³, 10⁵, and 10⁷, cells/g. No lactic starter culture was added. Samples were taken at different stages of processing to determine the microbial populations, percentage moisture, total acidity, pH, and enterotoxin content. Staphylococcal populations varying from about 10⁷ to 5 × 10⁸/g were detected during tempering of the salami. Enterotoxin A was detected in surface but not in core samples of salami inoculated with 10⁵ and 10⁷ S. aureus 265 cells/g. However, no enterotoxin B was detected in the salami inoculated with S. aureus 243, which requires a relatively high a_w for enterotoxin production. Staphylococcal counts were higher in surface samples than in core samples, attributable to the difference in oxygen, but there was no significant difference in microaerophilic lactic Kid bacteria in different portions of the salami.