CHAPTER III 

 PROPERTIES CF MILK 



Color. The coloring matter of milk is associated with the fat. 

 According to extensive investigations, made by Eckles and 

 Palmer at the Missouri Station, this color is due to carotin, so 

 called because it is the coloring matter of the carrot. It is found 

 in green plants and is closely associated with the chlorophyl, 

 which hides its presence. It is not manufactured by the animal. 

 Animals which produce milk rich in fat, in the form of large fat- 

 globules, possess the ability to utilize this coloring matter to a 

 greater degree than do animals which produce milk having a lower 

 fat content and smaller fat-globules. This explains the downward 

 gradation of the color of the fat in the milk as we pass from the 

 Guernsey and Jersey to the Shorthorn, Ayrshire and Holstein 

 breeds. 



Flavor. Milk has a sweet flavor, and a faint odor. Fresh 

 milk has a peculiar taste and odor, which pass off when it is 

 exposed to the air. The flavor is affected by foods and con- 

 ditions of the cow, as mentioned under u Abnormal Milk." 



Opacity of Milk. Milk is opaque, except when seen in very 

 thin layers; then it is slightly transparent. The opacity of milk 

 is due to the presence of the fat and nitrogenous matter. When 

 these substances are filtered away on a fine clay filter (the Cham- 

 berland), the filtrate which passes through is clear and trans- 

 parent. It has been maintained that the fat in milk is the chief 

 cause of its opacity, and that the percentage of fat could be 

 determined according to the degree of opacity and transparency 

 of milk with an instrument named pioscope; but it was soon found 

 out that the size of the fat-globules, as well as the number, had 

 considerable influence upon the degree of opacity of milk. For 

 that reason, this method of determining the amount of fat in 



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