Growth of enterotoxigenic Staphylococcus aureus in povi masima, a traditional Pacific island food.

AIMS

To obtain preliminary data on the microbiology and hurdles to pathogen growth in the traditional Pacific Island food, povi masima, which is essentially beef brisket cured in brine.

METHODS AND RESULTS

Six containers of povi masima were prepared and two were inoculated with five enterotoxigenic strains of Staphyloccocus aureus. The povi masima were divided into two lots each containing two uninoculated control and an inoculated container. Lot 1 was incubated at room temperature (20 degrees C) and lot 2 under refrigeration (4-5 degrees C) for up to 98 days. During storage, samples were removed and tested for aerobic plate count, coagulase-producing Staphylococci, Clostridium perfringens, staphylococcal enterotoxin and various chemical parameters of the food. Coagulase-producing Staphylococci and aerobic plate counts grew to high levels in both the inoculated and uninoculated lots stored at room temperature, but enterotoxin was only detected at one time point in these lots and this may represent a false positive result. The concentration of NaCl in the meat increased with time as concentrations equilibrated, and nitrite was rapidly lost in those lots stored at room temperature. Storage at 4-5 degrees C prevented proliferation of coagulase-producing Staphylococci.

CONCLUSIONS

For safe curing and storage, this food should be kept under refrigeration as this prevented growth of staphylococci. Optimum storage would also be achieved with improved attempts to ensure equal distribution of NaCl prior to storage.

SIGNIFICANCE AND IMPACT OF THE STUDY

Under conditions traditionally used to cure and store this food, enterotoxigenic staphylococci can grow to numbers where toxigenesis might occur, especially during the early stages of curing where the salt has not diffused from the brine into the meat.