An adapter medium (3) comprising a nutritive medium adapted to the development of kefir grains (1) and an enzymatically digestible substrate in a nutritive medium, is new. The weight ratio between the nutritive medium and the substrate is 1:1 in term of dry matter in the adapter medium. The chemical composition of the substrate is identical to the nonlacteous food. A receptacle (2) is used to retain the grains, and to allow an exchange of matters between grains and medium external to the receptacle, carries out the adaptation of the grains by immersing the grains in the adapter medium. An adapter medium (3) comprising a nutritive medium adapted to the development of kefir grains (1) and an enzymatically digestible substrate in a nutritive medium, is new. The weight ratio between the nutritive medium and the substrate is 1:1 in term of dry matter in the adapter medium. The chemical composition of the substrate is identical to the nonlacteous food. A receptacle (2) is used to retain the grains, and to allow an exchange of matters between grains and medium external to the receptacle, carries out the adaptation of the grains by immersing the grains in the adapter medium. The adapter medium is prepared by mixing the nutritive medium and a suitable quantity of a composition that dries corresponding to the target medium and prepared with the nutritive medium corresponding to minimum medium and with the substrate from soya, corn, corn, colza, barley, lupin, pea, beet, potato, carrot, cabbage, apple, apricot, pineapple, plum, kiwi, melon, cereal plant, oleaginous plant, proteagineous plant, vegetable, fruit, dairy ice cream, product of bakery or pastry making. The minimum medium is glucose (2 g/l), cysteine (2 g/l), glycine (25 mg/l), tryptophan (10 mg/l), epsom salt (15 mg/l), manganese sulfate (0.3 g/l), ferrous sulfate (0.1 g/l), sodium acetate (0.05 g/l), bipotassic phosphate (5 g/l), riboflavin (0.5 g/l) and thiamin (1 g/l). The adapter medium is prepared with a solid n
