Probiotic beverages are becoming popular among consumers as instant sources of gut-friendly bacteria. Natural kefir is such a traditional natural fermented product with several benefits on human health.

The conventional production process of kefir is done by adding kefir grains to fresh milk and allow the milk to be fermented and acidified at least for 24h. The Kefir grains are complex microbial communities and the exact interactions within these Kefir consortia is not yet completely understood. One obstacle in grain application is their slow growth in milk and possible changes of the microbial community during successive production cycles over time. This quite complicated and time-consuming traditional method of producing kefir with kefir-grains is not feasible at an industrial scale, which requires consistently controlled and efficient high growth rates of the microbial components to receive an end product (kefir) of consistently good and reliable quality at high production rate.

Two species L. kefiranofaciens and L. kefiri represent the most important and abundant bacteria of the natural kefir microbial community in kefir grain-based beverages. However, these two are very slow growing species and thus not used in industrial relevant starter cultures.

This invention provides a method to use these two species in a way that making the production of a synthetic kefir feasible for industrial scale production reassembling the organoleptic and health-benefiting characteristics of home-made kefirs more closely than current industrial kefirs.