Abstract: A lid that is used in household devices for preparing kefir using kefir grains. The lid comprises a rotating means located in the lid, a stirring rod connected to the rotating means, a container with holes for placing grains for fermentation within it and equipped with a cap and mounted on the stirring rod, and a control unit connected to the rotating means. The lid assembly is characterized in that the container with holes is affixed on the stirring rod in such a way that the axis of symmetry of the container is not aligned with the vertical axis of rotation of the stirring rod.