Purpose: In the present study, we investigated the microbiological contamination levels of small- and mid-sized dairy farms in Korea for suggesting managing and safety plans for the small- and mid-sized dairy farms. Also we verified effectiveness of teat washing and milk pasteurization as production process for control of microbiological hazard.
Methods: A total of 55 swab samples and 55 dairy products samples were collected between August and October 2014 from dairy farms located in Gyeong-gi and Jeon-la province. Mesophilic aerobic bacteria, coliforms and Escherichia coli were enumerated using 3M Petrifilm™. Salmonella, Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis and Enterococcus faecium were isolated according to the methods provided by Korean Food Code. In addition, the antibiotic susceptibility of isolated bacteria was determined by the disk diffusion method according to CLSI guideline.
Results: Mesophilic aerobic bacteria, coliforms and Escherichia coli were significantly reduced after teat washing and milk pasteurization. A total of 1 Salmonella, 12 S. aureus, 18 E. faecalis, and 18 E. faecium were isolated. Of these, 85.7% were from the samples collected samples obtained before teat washing and milk pasteurization. The difference in the antibiotic resistance patterns of milk isolates and cured cheese isolates was observed suggesting that cured cheeses contamination would occur after pasteurization production process.
Significance: Based on the results, we suggest that milk pasteurization and teat washing arethe most important processes for reducing the microbiological hazard in final dairy product. Furthermore, it is needed to prevent post-pasteurization contamination to ensure the safety of final dairy products.