Abstract:

Objective: The growth of Staphylococcus aureus and the production of enterotoxin in whipping cream were
studied. Methods: Two concentration levels of Staphylococcus aureus which produce enterotoxin were inoculated into
whipping cream stored at different temperatures; the low initial inoculum level was controlled in 2–3 (lg(CFU/g)), and the
high level was over 4 (1g(CFU/g)). The plate counts of Staphylococcus aureus and staphylococcal enterotoxin were tested
regularly. Results: The growth rate decreased with decreasing temperature. At the low inoculation level, Staphylococcus
aureus enterotoxin was detected only at 36 ℃ after 27 h. At the moderate temperature (25, 15 ℃), no Staphylococcus aureus
enterotoxin was detected. At the high inoculation level, staphylococcus enterotoxin were detected at 36 ℃after 12 h, 25 ℃
after 24 h and 15 ℃ after 66 h. At the low temperature (5 ℃), Staphylococcus aureus did not grow and no staphylococcus
enterotoxin was detected. Conclusion: As temperature rose, the growth rate of Staphylococcus aureus increased and the
time to produce enterotoxin was shortened. The time to produce enterotoxin for Staphylococcus aureus at the high initial
inoculation level was shorter than at the low initial inoculation level. The enterotoxin was generated in the late lag phase
where the plate count of Staphylococcus aureus reached 6 (1g(CFU/g)).

Key words: Staphylococcus aureus, enterotoxin, whipping cream