Farm to consumption risk assessment for Staphylococcus aureus and staphylococcal enterotoxins in fluid milk in China

- A quantitative risk assessment for Staphylococcus aureus in fluid milk in China was created.
- Dairy processing and direct to consumer routes were mainly considered.
- Storage temperature had a key effect on S. aureus concentration in processing plant route.
- The probability of milk with >105 CFU/mL S. aureus concentration before consumption was 0.
- Enterotoxin production had potential risk in direct to consumer route.

The objective of this study was to conduct a risk assessment to determine the food poisoning risk from the consumption of milk in China that might be contaminated by Staphylococcus aureus. Data related to prevalence and concentration of S. aureus in fluid raw milk in China were collected from the literature and used to calculate the initial contamination levels. Two main consumption routes were considered and the results of the Monte Carlo simulation model indicated that the storage temperature in the processing plant and heat processing of milk in the home were the primary factors affecting the S. aureus concentration at the processing plant and the home before consumption, respectively. Other important factors were distribution of log (D)-value's for S. aureus, storage temperature and time on farm, temperature of the thermal treatment of milk, and treatment time at the dairy processing plant. To minimize the risk of milk-borne staphylococcal intoxication in China, the key step appears to be the control of storage conditions during the period after heat treatment and before consumption. The risk assessment model developed in present study provides valuable information for Chinese government and dairy processors to improve milk safety. It also could provide valuable recommendations for Chinese consumer education on safe handling of milk products.