Abstract:
Possible contamination by Staphylococcus aureus of the production environment and of the
meat of a canned meat production factory was analysed. A total of 108 samples were taken from
nine critical control points, 13 of them were positive for S. aureus. None of the isolates produced
enterotoxins. To determine how much time can elapse between can seaming and sterilisation in
the autoclave without any risk of enterotoxin production by S. aureus, the growth and enterotoxin
production of three enterotoxin A producing strains of S. aureus (one ATCC strain and two field
strains) in canned meat before sterilisation was investigated at three different temperatures (37, 20 and
10 ◦C). Two types of meat were used, one with and one without sodium nitrite. In the canned products,
the spiked bacteria spread throughout the meat and reached high levels. Enterotoxin production was
shown to start 10 hours after incubation at 37 ◦C and after 48 h after incubation at 20 ◦C; the production
of enterotoxin was always detected in the transition between the exponential and the stationary
growth phase. At 10 ◦C, the enterotoxin was never detected. The statistical analysis of the data
showed that the difference between the two different types of meat was not statistically significant
(p value > 0.05). Since it is well known that following heat treatment, staphylococcal enterotoxins,
although still active (in in vivo assays), can be undetectable (loss of serological recognition) depending
on the food matrix and pH, it is quite difficult to foresee the impact of heat treatment on enterotoxin
activity. Therefore, although the bacteria are eliminated, the toxins may remain and cause food
poisoning. The significance of the results of this study towards implementing good manufacturing
practices and hazard analysis critical control points in a canned meat factory are discussed with
reference to the management of pre-retorting steps after seaming.
