ABSTRACT
Fermented foods usually have long storage lives and interesting nutritional values, which makes fermentation a very popular transformation technique all over the world, including for drink production. Even without sound scientific proof, consumers are generally encouraged by popular media to improve their health through fermented diets that bring a good amount of useful probiotics, making kefir increasingly fashionable. Milk kefir, thought to have its origins in the north Caucasus mountains, is still consumed by a lot of Russians. It is traditionally made by inoculating milk with kefir grains and keeping it in skin bags at room temperature for a day or more, depending on the conditions and fermentation level desired. Biochemical, metagenomic and metabolomic studies provide evidence of the large number of microorganisms in starting strains and the variety of possible bioactive compounds that could be formed during fermentation, and have to be followed by medical/clinical studies aimed at characterizing the potential health effects of regular kefir consumption.
