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Abstract

Kefir is a symbiotic fermented milk composed of lactic acid bacteria, acetic acid bacteria and yeasts. It is considered a functional-food, with many benefits to consumer health. Usually, kefir is home fermented with shared grains. Consequently, successive inoculations and manipulation of kefir grains could change the microbiota, decreasing its microbiological identity and quality. One indicator of quality and food safety is the coliform group, a member of Enterobacteriaceae family that can ferment lactose producing gas at 35ºC, and are very easily inactivated by sanitizer and thermals treatment. The thermotolerant coliforms are considered a total coliform subgroup, because these bacteria can ferment lactose producing gas at 45ºC. Escherichia coli is the main representative member of the thermotolerant coliforms and it is considered a possible fecal contamination indicator in fresh food. The present study aimed to assess the microbiological quality in kefir samples. Potential participants were reached through advertisement in the most popular Brazilian social networking sites and through instant messaging application for mobile devices. A total of 20 samples of fermented milk were obtained from people in Londrina city and evaluated for total and thermotolerant coliforms by the most-probable-number (MPN) method at the Laboratório de Inspeção de Produtos de Origem Animal of Universidade Estadual de Londrina. Among the 20 samples analyzed, six (30%) showed total coliform results above 100 MPN, the maximum limit established by the Identity and Quality Technical Regulation of Fermented Milk determined by the Ministério da Agricultura, Pecuária e Abastecimento. None sample showed more than 10 MPN for thermotolerant coliforms, standard allowed by statutory Brazilian regulation. The contamination found in this study is indicative of poor hygienic conditions, manipulation or environmental cross-contamination, suggesting that the hygienic sanitary conditions during preparation and conservation of kefir can be improved. Despite the low contamination for thermotolerant coliforms, it should be pointed that some non-E. coli coliforms may be potential enteropathogens. It can be concluded that most of kefir samples showed good hygienic/sanitary parameters and safety regarding some enteropathogenic bacteria. However, a considerable proportion (30%) of samples requires special attention, and it is worthwhile to invest on further studies that track the kefir preparation actions.

Institutions
  • 1 Centro de Ciências Agrárias / Universidade Estadual de Londrina
Track
  • Food Microbiology
Keywords
fermented milk
MOST PROBABLE NUMBER
food safety