82 Condensed Milk and Milk Powder 



curdle, tends toward the formation of a hard, unshakable 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 

 fiies, or any other condition which disturbs the physiological func- 

 tions 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 relatively 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," p. 28, to detect suspicious milk, and reject- 

 ing all milk that fails to reach the sanitary standard adopted by the 

 factory. 



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. In the manufacture of evaporated 

 milk, the batches of condensed milk in the vacuum pan must be rel- 

 atively small. This milk foams more in the pan than the heavier 

 sweetened condensed milk. Also, it is not condensed to as high a 

 degree of concentration. These factors reduce, therefore, the ca- 

 pacity of the pan. If the milk is heated in the hot wells, either by 

 steam jackets or by turning steam direct into the milk, it is advis- 

 able to use numerous small wells, rather than but one or a few 

 large ones. These small wells fill rapidly and the milk can be heated 

 without delay. This system makes it possible to render the bacteria 

 inactive and harmless practically as soon as the milk arrives, min- 

 imizing the danger of acid formation. 



Steam may be saved if the milk is forewarmed by running it 

 through coils inclosed in a chamber of exhaust steam, but the coils 



