CHAPTER X. 



THE ANALYSIS OF MILK. 



Introduction. In addition to the data obtained from the 

 sanitary inspection of dairies, the health officer should be in a 

 position to inform himself as to the composition of the milk as 

 sold. It is with a view to supplying such necessary aid that 

 these two chapters are here presented. It is not intended to 

 offer full and complete details for the analysis of milk but rather 

 to give some simple and at the same time accurate and reliable 

 tests for ascertaining not only the fat content but also whether 

 or not a milk has been in any way sophisticated. For further 

 details the reader is directed to the standard works mentioned 

 at the end of the chapter. 



Composition of milk. Normal cow's milk contains water 

 and the four nutrients, protein, fat, carbohydrate and ash or 

 mineral matter. 



Protein. Casein is the chief proteid of milk, constituting 

 fully 80% of the total amount, the next in importance being 

 albumen present to the amount of 15%. The remaining 5% 

 consists of different nitrogenous compounds, as lactoglobulin, 

 galactin, fibrin, etc. 



The protein content of normal herd milk does not vary 

 greatly, but that of individual cows has been known to range 

 from 2.07% to 6.69%. 



Fat. This is the most variable ingredient of milk. It does 

 not occur in solution but is found suspended in the, form of 

 minute globules. These vary in size not only with the milk of 

 the different breeds but also with the same breed or individual 

 during the period of lactation. It is a well known fact that 

 the Channel Island breeds. Jerseys and Guernseys, yield milk 

 showing the highest fat content and the Holstein-Friesian 

 cattle as a rule produce milk of a low fat content. 



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