Determining the safety of kefir grains for public health

Abstract

In this study, kefir grains and kefir produced from contaminated grains were investigated in terms of food safety. For this aim, traditional kefir grains were collected from distinct parts of Turkey, and their pathogenicity was examined. Typical and non-typical colonies were isolated on Violet Red Bile Agar and identified for the first time at species level. Antibiotic resistance and hemolytic activity of the isolates were also determined. Coliform and pathogenic bacteria was found in 19 out of 30 kefir grains tested (63.33%). Although Hafnia paralvei was the predominant group, Klebsiella oxytoca, Citrobacter freundii, Serratia liquefaciens, and Escherichia coli were also identified among the 27 strains as the pathogenic bacteria. It was found that the bacterial count of kefir produced from two kefir grains containing pathogenic bacteria was 8.44 log CFU/mL and 8.20 log CFU/mL at the end of the 10th day. All isolates were sensitive to ciprofloxacin, nalidixic acid, meropenem, and ertapenem but resistant to ampicillin and vancomycin. Furthermore, all strains were found to be β-hemolytic in that study. As a result, it was determined that traditionally produced kefir can be risky in terms of food safety due to contaminated kefir grains and this risk continues throughout consumption.