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 

 acidity there should be no difficulty in getting a good separation 

 at a temperature varying between 115° and 130° F. (46.11° and 54.44° 

 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 



