There are two methods given by Flügge[29] for the preparation of keffir:
"In the first, the dry brown kefir grains of commerce are allowed to lie in water for five or six hours until they swell; they are then carefully washed and placed in fresh milk, which should be changed once or twice a day until the grains become pure white in colour and when placed in fresh milk, quickly mount to the surface—twenty to thirty minutes. One litre of milk is then poured into a flask, and a full tablespoonful of the prepared _körner_ added to it. This is allowed to stand open for five to eight hours; the flask is then closed and kept at 18° C. It should be shaken every two hours. At the end of twenty-four hours the milk is poured through a fine sieve into another flask, which must not be more than four fifths full. This is corked and allowed to stand, being shaken from time to time. At the end of twenty-four hours a drink is obtained which contains but little carbon-dioxide or alcohol. Usually it is not drunk until the second day, when, upon standing, two layers are formed, the lower milky, translucent; and the upper containing fine flakes of casein. When shaken it has a cream-like consistence. On the third day it again becomes thin and very acid. The second method is used when one has a good kefir and two or three days to start with. Three or four parts of fresh cows' milk are added to one part of this and poured into flasks which are allowed to stand for forty-eight hours with occasional shaking. When the drink is ready for use, a portion (one fifth to one third) is left in the flask as ferment for a fresh quantity of milk. The temperature should be maintained at about 18° C., but at the commencement a higher temperature is desirable. The grains should be carefully cleaned from time to time and broken up to the size of peas. The clean grains may be dried upon blotting-paper, in the sun, or in the vicinity of a stove; when dried in the air they retain their power to germinate for a long time."
_Leben._—In our earlier references to fermented milks in scriptural times, we observed that alcoholic fermented milks were not permitted to be presented at the altar. Such offerings, however, were quite allowable amongst the ancient Egyptians, the Arabs and Carthaginians,[30] and from remote antiquity these nations placed great value on this product. Leben, which is peculiarly associated with Egypt, is a soured milk prepared from the milk of buffaloes, cows, or goats. It is usually prepared by the boiling of the fresh milk over a slow fire, after which some fermented milk from a previous preparation is added to the warm article, and the fermentation takes place rapidly and is considered to be complete in about six hours.[31] The Egyptian leben is valued so highly that it is offered in hospitality to the passing stranger, and it is regarded as so much of a duty to present this milk, that in some parts of Arabia it would be looked upon as scandalous if any payment were received in return.[32]