118 EVAPORATED MILK HEATING 



casein to curdle, tends toward the formation of a hard, unshak- 

 able coagulum during sterilization, and makes the manufacture 

 of a marketable product difficult. Abnormal milk of this type 

 may come from cows approaching parturition, or too soon after 

 calving, or milk from cows suffering from disease, generalized 

 or local, or from cows in poor and abnormal physical condition; 

 which may be brought about by poor care, over-feeding, feeding 

 the wrong kinds of feed, or feed in poor condition, exposure to 

 abnormally hot weather and flies, or any other condition which 

 disturbs the physiological functions of the animal and thereby 

 affects the physical, chemical, and physiological properties of 

 the milk; or it may be due to improper care of the milk, causing 

 it to be excessively contaminated with germ life, or to be rel- 

 atively high in acid. All such milk renders the quality of the 

 finished product uncertain and may result in heavy loss. 



In view of these facts it is obvious that the greatest care 

 should be exercised on the receiving platform, inspecting every 

 can of milk, using the most reliable means, as recommended in 

 Chapter III on "Control of Quality," to detect suspicious milk, 

 and rejecting all m'ilk that fails to reach the sanitary standard 

 adopted by the factory. 



Standardizing. -In order to insure in the finished product 

 the percentage relation of fat to solids not fat that meets with 

 the Federal Standard or with any other standard desired, the 

 fluid milk should be accurately standardized. For this purpose 

 each batch of fluid milk must be correctly tested for per cent fat 

 and per cent solids not fat. On the basis of these tests, the 

 amount of cream or skim milk which it is necessary to remove 

 or to add, as the case may be, can then be readily calculated. 

 For detailed directions on standardizing the milk to any desired 

 standard see Chapter XXIX on "Standardization." 



HEATING THE MILK. 



The equipment for heating the milk should be such as to 

 enable the factory to heat the milk with the least possible delay 

 so as to avoid the development of acid, or to make possible the 

 prompt cooling of the milk upon its arrival to a temperature at 

 which bacterial development is checked. In the manufacture of 

 evaporated milk, the batches of condensed milk in the vacuum 



