CHAPTER XI 



Methods of Testing Milk and Milk Products 

 for Adulterations 



Milk is commonly adulterated in one of the follow- 

 ing ways: (i) By addition of water, (2) by removal 

 of fat (skimming) or addition of skim-milk, (3) by 

 addition of substances not normally found in milk, 

 such as preservatives and coloring matter. All these 

 forms of adulteration may occur in the same milk. 



DETECTION OF ADDED WATER IN MILK 



Since water in milk is the same chemical compound 

 as the water found^ everywhere else, it is impossible 

 to identify added water in milk by any direct test for 

 special properties. The presence of added water in 

 milk can be learned with certainty only by indirect 

 means and even then not with certainty in all sus- 

 pected cases. An examination of milk direct from 

 the cow or herd, when this is possible, may settle the 

 question of watering. The lactometer, while unrelia- 

 ble as a sure means of detecting added water in milk, 

 may give a helpful suggestion, used as a preliminary 

 test. Thus, if a milk shows a specific gravity under 

 1.028, it is open to the suspicion of being watered, and 

 should then be carefully examined in other ways. 



Most states fix legal standards for the per cent, of 

 water, solids, fat, and solids-not-fat in milk, and any 



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