26 CITY MILK SUPPLY 



has been condensed in the ratio of 2.5 parts of fresh milk to 1 of condensed. 

 In the process the milk is not heated high enough to kill the moulds and 

 bacteria that are in the milk but the syrupy consistency of the finished 

 product usually keeps them from developing. However, when the milk 

 is diluted for use they may grow. The addition of sugar to the milk 

 before it is condensed makes this sort of milk radically different from 

 cow's milk. 



In manufacturing evaporated milk no sugar is added. The milk is 

 condensed in the ratio of about 2.5 : 1 and is afterward sterilized at 228 

 to 236F. or at even higher temperature. This high temperature gener- 

 ally makes the milk sterile but it precipitates most of the albumin in the 

 milk and very probably affects the milk sugar so that the evaporated 

 milk, too, is quite different from cow's milk. 



Milk powder is a recent comer to the market but it has found a ready 

 market and many believe that it will have an important influence on the 

 city milk trade. The chief difficulty that it has had to meet is that the 

 less stable fatty acids of butterfat decompose in light and air with the 

 production of a tallowy flavor. Powdered skim-milk does not have to 

 contend with this obstacle and so is a success. Milk powders are not 

 sterile but they are protected against the action of microbes by their 

 lack of moisture. As they absorb moisture on exposure to the air they 

 are kept in parchment-lined cartons or barrels. 



Sources 



LEACH, "Food Inspection and Analysis." 2nd Ed., 1909, pp. 124-208. 



WING, "Milk and its Products," 1913, pp. 16-34. 



WARD, "Pure Milk and the Public Health," 1909, pp. 174-185. 



VAN SLYKE, " Modern Methods of Testing Milk Products," 1913. 



FARRINGTON and WOLL, "Testing Milk and its Products," 1912. 



WILCOX, "Production and Inspection of Milk," Hawaii Ag. Expt. Sta., 1912. 



INGLE, "Manual of Agricultural Chemistry," 1902, pp. 197-233. 



SAVAGE, "Milk and the Public Health," 1912, pp. 1-16. 



" Hygienic Laboratory Bulletin 56," U. S. Public Health and Marine Hospital 



Service, 1909. 



RICHMOND, "Dairy Chemistry," 1914. 

 MICHELS, "Market Dairying and Milk Products," 1912. 

 BARNHART, J. M., "The Composition of Milk." 

 ANDERSON, "Studies in the Range of Variation of the Per cent, of Butterfat in 



Milk of Individual Cows," Bull. 71, Mich. Ag. College. 

 ECKLES, "Influence of Fatness of Cow at Parturition on Per Cent, of Fat in Milk," 



Bui. 100 Missouri Ag. Expt. Sta. 

 ECKLES and SHAW, "Influence of Stage of Lactation on the Composition and 



Properties of Milk," Bui. 155 B. A. I., U. S. Dept. of Ag. 

 SHAW and ECKLES, "A Chemical and Physical Study of the Large and Small Fat 



Globules in Cow's Milk," Bui. Ill, B. A. I., U. S. Dept. of Ag. 

 ECKLES and SHAW, "The Influence of Breed and Individuality on the Composition 



and Properties of Milk," Bui 156, B. A. I., U. S. Dept. of Ag. 



