If the kefir becomes very acidic, the milk protein begins to coagulate and the whey settles: two layers form: a white, thick layer, which is the curd, and a yellowish, watery layer, which is the whey.
In this case, you can simply stir vigorously or hang the kefir through a cloth and make fresh cheese. To get your kefir lumps out of the thick curd, you can carefully pass it through a coarse-meshed sieve with a spoon.
If you don't want the kefir to separate again the next time, make sure that there is not too much acidity, e.g. by:
- Allow the kefir to ferment for a shorter time and stir regularly.
- Use fewer nodules in relation to the milk (1 tbsp nodules per 1 l milk) and/or
- Let the kefir ferment a little slower in a slightly cooler place.