Koumiss is a fermented milk, prepared by both lactic acid and alcoholic fermentation. It is made from the milk of a certain breed of mares in South-eastern Russia; it is also made from cow's milk, to which an artificial ferment has been added. The milk is mixed with a koumiss ferment, the lactic acid ferment changing some of the sugar into lactic acid, while another part of the sugar is converted into alcohol and carbonic acid. Koumiss is an acid effervescing drink, with an agreeable bitter taste, and contains from I to 2 per cent, of alcohol. The strength of koumiss varies with the duration of fermentation, as shown in the following table. It is very sensitive to temperature changes, and its composition is always changing, unless the fermentation is controlled by extreme cold. It is very easily digested, being much more digestible than milk (see also p. 540).

Koumiss - Duration Of Fermentation