Survival of Staphylococcus aureus during the manufacture and ripening of camembert cheese : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Palmerston North, New Zealand

Abstract

Staphylococcal Food Poisoning (SFP) is the third most common cause of food poisoning internationally, caused by an enterotoxin produced by Staphylococcus aureus. S. aureus contamination in dairy products, including cheese, can lead to SFP. The survivability of S. aureus during the manufacture and ripening of Camembert cheese was the focus of this study. Camembert cheeses were manufactured using pasteurized milk inoculated with one of three S. aureus strains, comprising two reference strains ATCC 4163, ATCC 9144 and one dairy strain 172 RR. Each strain was tested in triplicate. The results showed that manufacturing and ripening of Camembert cheese reduced the risk of food safety associated with contamination with S. aureus with a 1.6 to 3.1 log reduction. The largest decrease occurred following drainage, which was particularly evident in 172 RR, and coincided with the lowest pH. The combined effect of culture blend (starter and secondary flora) activity and low pH are believed to contribute to the death of S. aureus.