Study on the Growth and Enterotoxin Production by Staphylococcus aureus in Canned Meat before Retorting

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.

Staphylococcus aureus Toxins: Armaments for a Significant Pathogen

“…Two papers within this issue are centered on S. aureus enterotoxins. Grispoldi et al studied enterotoxin production in S. aureus within canned meat [12]. The time between seaming and sterilization was examined.…”

Large-Scale Staphylococcus aureus Foodborne Disease Poisoning Outbreak among Primary School Children

“…This level of enterotoxin A is well within the widely recognized dose required to cause foodborne illnesses. It was pointed out in a recent study by Grispoldi and colleagues that during the production process of canned meat, enterotoxin was only detectable in bacteria-spiked products after 10 hrs at 37 °C or 48 hrs at 20 °C, and no enterotoxin was detected in products kept at 10 °C [30]. Thus, the conditions in and duration for which cooked food was kept in the school canteen before being served to the children would also significantly affect the enterotoxin level in food items.…”

Staphylococcus aureus enterotoxin in food of animal origin and staphylococcal food poisoning risk assessment from farm to table

“…Another study demonstrated that NaCl (4.5%) and glucose stress can decrease sed expression (Sihto et al 2015). It has been reported that nitrites (food additives often used as a preservative and colour fixative in cured meat) have little to no inhibitory effect on the growth and enterotoxin production by S. aureus at the concentration permitted by food regulations (Grispoldi et al 2019c).…”

“…In addition, many growth and inactivation curve studies are available online. This data can be useful to design food processes to prevent the growth and production of SEs (Obeso et al 2010;Grispoldi et al 2019c). The main challenges in the development of predictive models are that food contamination is often incidental with a difference of just a few cells, together with a highly variable strain level.…”