Many years ago, when fridges weren't yet, people had a difficult task: how to keep and process milk, its often large number, without fridge.
In a post or in the summer when there was surplus of milk, it was poured in big clay jugs. Such ware was made of very porous clay especially for milk. Then jugs put in a cellar. After a while milk turned sour, and in jugs sour cream and curdled milk were formed. Then, if these products couldn't be eaten, they were processed further. Sour cream was shaken up and received a desi which could be stored long – on cold, in the pottery which is filled in with serum.
Desi was also melted, and stored in such look in makitra – clay pots with a wide throat. Often added salt to a melted desi. Such oil could be stored several months and if from above it was filled in with the kindled pork fat – that longer. Buttermilk which turned out together with oil was given on a forage to cattle. If buttermilk could be used in food, on it kneaded dough, baked bread or pies.
Did cottage cheese of curdled milk, placing its baking plate bends. If cottage cheese needed to be kept for a long time, cottage cheese was "melted" several times to make it as it is possible for the land, then added some egg, baked to a rumyanost, stamped such cottage cheese in the form of pancakes in pottery, prisalivat, and filled in with the kindled desi. So cheese which could be stored and not spoil long turned out.
These ways allowed to process even a large number of milk and to keep useful and nutritious products for long time.