Microbiological and physicochemical characteristics of cow's milk kefir produced with grains obtained from domestic cultivation

Kefir is a traditional fermented drink originating from regions of the Caucasus and Eastern Europe, produced by directly adding kefir grains to milk. The study aimed to evaluate the microbiological and physicochemical characteristics of beverages made with grains obtained from domestic cultivation. Beverages were prepared by inoculating the grains in UHT whole milk in a 1:15 (w/v) ratio, fermented for 24h, and filtered to separate the grains. Lactic bacteria were quantified on MRS Agar and yeast counts on BDA Agar. Enumeration of total and thermotolerant coliforms was performed using the multiple tube technique in Broth VB and EC, respectively. The titratable acidity was determined by titration with 0.1N NaOH solution. The lactose content was determined by the Fehling method. The presence of total coliforms was found in three samples and thermotolerant coliforms in just one. Lower levels of lactose were observed in samples with higher growth of lactic acid bacteria and yeasts. Higher levels of titratable acidity were observed in samples that presented lower pH values and higher growth of lactic acid bacteria. Most samples meet the established parameters for counting lactic acid bacteria. Two samples showed yeast count < 10 CFU/mL. The presence of coliforms in three samples reveals flaws in the hygienic conditions during the continuous transfers or even in the handling or storage stages. It is important to emphasize adopting of good hygienic practices when obtaining the grains and making the drink, aiming at a safe product for consumption.