Another disease consists in the predominance of certain butyric acid bacteria which impart an unpleasant rancid taste to the keffir (Podowyssozki). This is generally attributed to the use of rich milk, or too high a temperature during preparation.
_Koumiss._—Another product of the combined action of lactic acid and alcohol-producing organisms is called koumiss, kumys, milk-wine, lac fermentation, or vinum lactis. In the steppes of Southern Russia and Asia, as we have seen,[59] it is prepared chiefly from mares' milk, but occasionally from that of camels and jennets. The name is said to be derived from that of a tribe mentioned by Xenophon and Pliny, viz., the Kumanen, by whom its preparation was practised. After the war with the Tartars in 1215 its use was adopted by the latter people, and eventually spread to the Turkomanen, Kalmucks, Khirgiz, Mongolians, etc.
Rubruck, in 1253, records the use of a fermented drink—kosmos—prepared from mares' milk, and about the same time Marco Polo mentions the occurrence of a milk-wine, chumis or chemius, among the Tartars. The fact that the Tartars were seldom ill, and were almost invariably free from lung troubles, led to an influx of visitors from surrounding countries, until finally its use spread to Russia, Austria, and Germany. At the present time the best koumiss is that produced in the province of Orenburg; but specially equipped koumiss establishments, under the control of physicians, exist in Odessa, Samara, Ufa in the Urals, and other districts. The curative properties of koumiss have long been recognised and its use is indicated in cases of indigestion, chlorosis, scurvy, tuberculosis, etc.
Rubinsky states that, among the nomadic tribe, of Khirgiz and Kalmucks, a special leathern bottle (Turssuk, Orroth, or Soaba) is used for the preparation of koumiss, while wooden tubs (Tschiljak) similar in shape to the old-fashioned churn are used by the Bashkirs, and in koumiss establishments.
The fermentation is induced by the addition of koumiss to fresh mares' milk, in proportions which vary according to the cleanliness observed in the actual preparation. Where the process is carefully controlled, one part of koumiss to ten parts of milk is often used, but where gross infection from outside sources takes place one part of koumiss to three parts of milk is taken. The mixture is stirred at frequent intervals, and stored at a temperature of 73°-90° F. Weak koumiss is obtained after twenty to twenty-four hours in winter and twelve to fourteen hours in summer, but is scarcely ever consumed immediately, as it possesses a strong purgative action.