Microbial risk assessment of staphylococcal food poisoning in Korean kimbab

The objective of this study was to conduct a preliminary microbial risk assessment for Staphylococcus aureus in kimbab, and then propose appropriate guidelines for its preparation and storage. Kimbab is a ready-to-eat product, popular in Korea, made of various foods surrounded by rice and seaweed. Because it is usually prepared by hand and stored at room temperature, it can be contaminated with S. aureus. Data on the prevalence, concentration and growth of S. aureus in kimbab as well as typical ambient temperatures in Seoul were collected; probability distributions were then selected to describe these data. A Monte Carlo simulation model was created using @risk. When current Korean retail data on S. aureus prevalence and concentration were used as inputs, the simulation predicted that the S. aureus concentration would be between 4.0 and 4.9 log CFU/g after 1 h of storage at ambient temperature during the warmest part of the year (March through November). Conversely, by assuming a starting concentration of 1 cell/g, the simulation predicted that the S. aureus concentration would reach 4.4 log CFU/g after 5 h of ambient storage in May and 3.4 log CFU/g in October. Our results suggest that, given the current prevalence and concentration of S. aureus found in kimbab at retail outlets, the product should be consumed within 1 h of purchase. Our results also indicate that if Korean consumers wish to safely store kimbab for 5 h at ambient temperature, S. aureus concentration should not exceed 1 CFU/g at the time of preparation.