Purpose: This study was to assess the microbial contamination of retail beef in Seoul, Korea, and to predict its shelf life via the growth modeling of inert microbes present in retail beef using a mathematical quantitative model.
Methods: The quantity of beef specimens was 100. Total aerobic bacteria, coliform bacteria, Escherichia coli, Bacillus cereus, Staphylococcus aureus, E. coli O157:H7, Salmonella spp., and Listeria monocytogenes present in beef specimens were quantified using plate count methods. To investigate the growth of inert microbes present in retail beef, beef specimens were stored at 5, 10, 15, 20, and 25°C, and total aerobic bacteria in beef specimens were counted. The growth characteristics of total aerobic bacteria present in beef specimens were analyzed with a mathematical quantitative model (modified-Gompertz equation).
Results: The average value of total aerobic bacteria for 100 retail beefs was 4.57 log CFU/g. Coliform bacteria and E. coli were detected in 84 and 19 out of 100, respectively, but no other pathogens were detected. The analysis of the growth characteristics of inert aerobic bacteria in retail beef reveals that its microbial safety could not be guaranteed if beef, contaminated with bacteria at the level of 4 log CFU/g, was stored longer than 5 days at 5°C.
Significance: This study provided substantial information on the microbial safety of retail beef in Seoul, Korea, which enabled for the prediction of the shelf life of beef at refrigerated temperature.