16 
BULLETIN 319, U. S. DEPARTMENT OF AGRICULTURE. 
Hammarsten (31) shows in the following table the changes brought 
about in eow ? s milk by this fermentation : 
Chemical analysis of kefir. 
2 days 
old". 
4 days 
old. 
6 days 
old. 
Casein 
2.570 
.425 
.071 
3.700 
-4.619 
.641 
.665 
.230 
2.586 
.405 
.089 
2.238 
3.630 
.624 
.832 
.810 
2.564 
Lactalbumin 
.390 
.120 
Lactose 
1.670 
Fat 
3.626 
Ash 
.630 
.900 
Alcohol 
1.100 
It will be observed that the changes were confined almost entirely 
to the lactose and its by-products. The casein remained unchanged 
and the increase in the peptones was insignificant. The lactalbumin 
decreased slightly. The casein of kefir is, according to this chemist, 
not especially soluble, but may be more easily digestible because of its 
finely divided condition. The lactose diminished appreciably, and 
there was a corresponding augmentation of alcohol and lactic acid. 
A certain part of the lactose is consumed in the formation of carbon 
dioxid gas not included in this analysis. 
The following directions are given for making kefir when the 
grains are available: The dry grains are softened by soaking in 
warm water, which should be changed several times. TVTien the 
grains rise to the surface and become white and gelatinous they are 
ready for use. One part of these grains is used to three parts of 
milk which has been thoroughly heated to destroy the bacteria 
already present. The bottles in which the milk and grains are placed 
should not be stoppered but should be protected from the dust by 
cloths, inverted cups, or plugs of cotton. They are held at a tem- 
perature at or near 14° to 16° C. (57° to 60° F.), and stirred or 
shaken frequently. After eight to ten hours the milk is strained 
through cloth and put into tightly stopped bottles at the same tem- 
perature as before. The bottles should be shaken every few hours 
to prevent the formation of lumps of precipitated casein. The kefir 
is ready for use at the end of 21 hours ; if held longer than this it 
is advisable to keep it on ice to check the fermentation. The tem- 
perature at which the milk is fermented is important in controlling 
the relative amounts of alcohol and lactic acid. At higher tempera- 
tures the percentage of alcohol is increased, while as the temperature 
is lowered the alcoholic fermentation diminishes and the quantity 
of lactic acid formed is greater. After the fermentation is once 
started the grains may be discarded and new kefir made by adding 
one part of the fermented milk to three or four of fresh milk. In 
