2 BULLETIN 661, U. S. DEPARTMENT OF AGRICULTURE. 
and probably can obtain greater efficiency through quality rather 
than quantity. When a good grade of cream is received, not only 
can a high-quality butter be made, but the buttermilk can be more 
profitably utilized. 
In the past skim-milk casein is the only kind that has been made 
in large quantities. However, many creameries have a considerable 
quantity of buttermilk, which is not disposed of to the best advan- 
tage, and this by-product can be made to realize a profit to the 
creamery and produce greater returns to the farmer if it is made 
into a good grade of casein. It is possible to make profitably a good 
grade of casein from buttermilk when good raw material is received, 
provided the buttermilk does not bring exceptional prices for food. 
It is, of course, advisable to convert the buttermilk into food prod- 
ucts when proper markets can be obtained, as greater profits usually 
can be derived from it in that form. It is not always possible to 
utilize all the buttermilk to the best advantage as a food product, 
and it is important to be able to turn the surplus into casein, which 
is a good-keeping product and finds a ready market. As dried casein 
of good quality can be marketed in unlimited quantities, its manu- 
facture acts as a safety valve in utilizing any surplus buttermilk or 
skim milk. 
THE MANUFACTURE OF CASEIN FROM BUTTERMILK. 
The recovery of casein from buttermilk by the method to be out- 
lined is dependent upon the normal acidity of the buttermilk. Sweet 
buttermilk must be ripened until the proper degree of acidity has 
developed. The sour buttermilk from the churn, or that which has 
developed the required acidity by ripening, is heated sufficiently 
to cause a rapid separation of the curd and whey. Owing to the 
fineness of buttermilk curd every precaution must be taken to pre- 
vent it from being broken up any finer, which makes handling 
more difficult. Turning steam directly into the buttermilk has too 
great a tendency to break the curd up and make handling more 
difficult. The method devised for heating the buttermilk to obtain 
a rapid and clear separation of the curd in such manner as to give 
favorable conditions throughout the rest of the process consists in 
running it through a steam jet or ejector. In this way the desired 
temperature can be obtained in a rapid and efficient manner and 
with very little agitation of the curd. With buttermilk of sufficient 
acidit} T there should be no difficulty in getting a good separation 
at a temperature varying between 115° and 130° F. (46.11° and 54.41° 
C). (See fig. 1.) The proper temperature to get the characteristic 
clear and rapid separation of the curd from a given lot of butter- 
milk can readily be ascertained at the start of a run by catching 
