168 



ChumicaIv Composition 



some localities and at certain times of the year the best results 

 may be obtained with evaporated milk containing 28 per cent 

 solids. In other localities it may be difficult at certain seasons 

 of the year, to incorporate more than 24 per cent solids without 

 injuring or destroying the marketable properties of the product.^ 

 Butterfat. — The fat varies with the per cent of fat in the 

 fresh milk and with the degree of concentration. No fat is lost 

 during the process of condensing and sterilizing.^ It has been 

 claimed by some that in the process of manufacture, the volatile 

 fatty acids escape and that the evaporated milk therefore con- 

 tains less fat than the fresh milk from which it is made, times 

 the degree of concentration. If this were true the loss of fat in 

 the evaporated milk would not exceed .25 of 1 per cent. But 

 analyses show that the fat in the evaporated milk is entirely 

 normal in composition and contains the same proportion of 

 volatile fatty acids as the fat in the fresh milk. 



The Composition of Milk Fats in Evaporated Milk^ 



Date of 

 Manufacture 



August, 1908 



November, 1908 



Melting point of 

 mixed fats 



33.3 degrees C. 



33.4 degrees C. 



Melting point of 



insoluble 



fatty acids 



41.0 degrees C. 

 41.2 degrees C. 



In the evaporated milk there is a strong tendency for the 

 fat to separate out during storage and to churn in transportation. 

 This is largely avoided by the proper adjustment of the steriliz- 

 ing process and by use of the homogenizer. 



Proteids. — (The proteids vary with the per cent of total 

 proteids in the fresh milk and the degree of concentration. 

 Similar to the case of sweetened condensed milk there is a 

 tendency of a slight loss of proteids in evaporated milk due to 

 mechanical adhesion of a part of the precipitated curd to the 

 heating surfaces in the forewarmers and in the vacuum pan. 



Most of the coagulable milk albbumin is precipitated. Fresh 

 milk contains about .16 per cent of albumin that is not coagu- 

 lable by heat.^ The relation of soluble and insoluble curd is 



1 Hunziker, Indiana Agricultural Experiment Station, Twenty-first Annual 

 Report, 1908, pages 67-68. 



2 Hunziker and Spitzer, Indiana Agricultural Experiment Station, Bulletin 

 No. 134. 



= Hunziker, Indiana Agricultural Experiment Station, Bulletin No. 143. 



