18 DEPARTMENT BULLETIN 319, U. S. DEPT. OF AGRICULTURE 
the extent of the alcoholic fermentation. Theoretically about one- 
half of fermented sugar may be converted into alcohol ; that is, milk 
to which 1 per cent of cane sugar has been added may contain after 
the fermentation 0.5 per cent of alcohol. The quantity of sugar 
added should be governed by the amount of carbon dioxide it is 
desired to have in the finished product. This should be sufficient to 
make the kefir distinctly effervescent and impart to it the peculiar, 
sharp taste of charged water, but should not be developed enough 
to blow the fluid out of the bottles when the stoppers are removed. 
Experience shows that 1 to 1.5 per cent of sugar will give the proper 
amount of gas. This may be approximated by adding sugar in the 
proportion of 2 even teaspoonfuls of sugar to each pint of milk. 
When the buttermilk and the yeast culture are ready, the sugar is 
dissolved in the buttermilk. 
The yeast culture is added to the buttermilk in the proportion of 
1 teaspoonful to 1 quart of buttermilk. 
The buttermilk is mixed thoroughly and bottled. The bottles 
should be ver}^ strong, as sufficient gas pressure is sometimes gener- 
ated to break ordinary bottles. The heavy bottles used for ginger 
ale or other carbonated drinks answer this purpose very well. They 
should be carefully cleaned and boiled or steamed before being filled 
and then stoppered tightly. The stoppers should be wired or tied 
securely in place. 
The product is put in a cool place to ferment. If the fermentation 
is too active the kefir will have a yeasty taste, and the curd is likely 
to become lumpv and filled with large gas bubbles. A temperature 
of 18° to 21° C, (65° to 70° F.) will be found satisfactory for 
kefir which is to be used on the third or fourth day. The floor of a 
cool cellar is a convenient place to ferment kefir made in the home. 
The bottles should be shaken as often as may be necessary to keep the 
curd in a finely divided condition. The finished product should be 
smooth and creamy, effervesce rapidly when poured from the bottle, 
and have the pleasant, acid taste of buttermilk, with the added sharp- 
ness caused by the gas and the trace of alcohol. Kefir 2 or 3 days 
old may have a 3 7 easty taste, but if it has been properly made this 
will disappear as the fermentation of the sugar nears completion; 
made under these conditions, it should be used when 3 to 5 days 
old, but if put on ice it may be held for a week or even longer. 
KUMISS 
The missionary monks and other wanderers who first penetrated 
ihe undulating, treeless plains of European Russia and central and 
southwestern Asia brought back descriptions of a fermented drink 
which in the light of more recent investigations is easily recognized 
as kumiss. These vast prairies are inhabited by tribes of nomads 
who live in tents or squalid huts in the winter and wander during the 
summer, seeking pasture for their horses, their herds of cattle, or 
flocks of sheep. They are all horsemen, and by a process of selection 
in which they have probably played only a passive part they have 
developed an exceptionally hardy race of horses. The mares give 
much more than the ordinary quantity of milk, which constitutes 
almost the entire food of the people during the summer. This is 
never used in the fresh condition but is fermented to make kumiss. 
