TURK 2025

This study aimed to investigate the growth and survival of Escherichia coli O157:H7 ATCC 43894, Listeria monocytogenes ATCC 7644, and Staphylococcus aureus NCTC 10654 in koumiss produced from raw mare’s milk during fermentation. The pathogens were individually inoculated into raw mare’s milk (Group 1: E. coli, Group 2: L. monocytogenes, Group 3: S. aureus) and also as a mixture (Group 4), each at a level of 10⁶ cfu/mL. Fermentation was initiated by adding previously fermented koumiss as a traditional starter culture, and all groups were incubated at 25°C. Samples were taken at 0, 1, 5, and 24 hours, as well as on days 2, 3, 4, and 5, for microbiological and chemical analyses. During fermentation, pH, dry matter, and protein content decreased, while titratable acidity and alcohol content increased. A positive correlation was observed between the growth of total aerobic mesophilic bacteria, psychrophilic aerobic bacteria, Lactobacillus spp., and the pathogenic microorganisms. In contrast, a negative correlation was found between the pathogens and yeast and mold counts. The number of pathogenic microorganisms declined over time and was completely eliminated by the second day of fermentation. It is concluded that the inhibition of pathogens was associated with the increase in titratable acidity and alcohol content, and the decrease in pH. Since koumiss produced from raw mare’s milk may pose a public health risk before the second day of fermentation, it is recommended that producers adopt better hygienic practices and raise their awareness regarding food safety.
Note: This study was produced from the author’s doctoral dissertation.