Purpose: The objective of this study was to assess microbial risk of Staphylococcus aureus in various cheeses.
Methods: A quantitative microbial risk assessment for natural and processed cheeses was conducted from factory to table. In hazard identification, S. aureus hazard in the cheeses and microbial criteria were searched through literatures. For exposure assessment, the contamination level of S. aureus in cheeses was evaluated, and time and temperature distributions in cheese processing and distribution chain were also measured. Predictive models developed in other study were used to calculate maximum specific growth rate and lag phage duration of S. aureus. In hazard characterization, a dose-response model for S. aureus was searched, and the model was used to estimate the risk of illness. With these data, in risk characterization, the risk of illness per person per day was estimated by simulation using @RISK.
Results: Monitoring results for S. aureus on cheeses from factory and grocery stores showed that S. aureus cell counts were below detection limits (0.30-0.45 log CFU/g). Thus, the prevalence of S. aureus on cheeses was very low. Under time and temperature distribution collected from grocery store and home, predictive models showed no significant S. aureus growth in natural and processed cheeses. The result of risk characterization for S. aureus in natural and processed cheeses showed that the mean and maximum value for the probability of illness per person a day in processed cheese were 2.24×10-9 and 7.97×10-6, respectively, and in natural cheese, 7.84×10-10 and 2.32×10-6, respectively.
Significance: These results should be useful in establishing the microbial regulation to control S. aureus in various cheeses.