12; 



Butter Fat and Butter Fat Constants 



By George SnxzER. 



I. 



When the greater portion of fat i.s removed from milk by skimming or 

 separating, and the resulting cream subject to powerful mechanical treat- 

 ment, the milk fat passes from the licjuid into the solid state, by cooling the 

 mixture below the melting point of butter fat. The fat globules thus collect 

 and are formed into grains. By washing and working, the geater portion 

 of buttermilk i.s removed and the substance called butter is left. Salt in 

 suitable ciuantity is added according to the demands of the consumer. The 

 analysis of butter, known as proximate analysis, consists in determining the 

 per cent, of moisture, salt, proteids and fat. 



The analysis of butter has reached a degree of great importance. The 

 proximate analysis does not indicate whether the sample has been adulter- 

 ated, but indicates its present condition, and may give some information as to 

 the method of manufacture. 



Since the enactment of the Pure Food Law, butter containing K) per cent, 

 or more moisture is held as adulterated butter. The com.pojition of butter 

 is a variable one, the proportion of different constituents, as fat, moisture, 

 salt, etc., are variable, depending on methods of manufacture. Butter is then 

 only a mixture of the above constituents, or properly speaking an emulsion 

 of butter fat and water, containing salt, curd, and milk sugar. But when v.e 

 treat of butter fat we have a substance of definite characteristic chemical 

 composition. Both solid and liquid fats are formed by the combination of 

 glycerol and fatty acids. Glycerol is a trihydric alcohol and consequently 

 behaves as a trihydric base. It can then combine with the radicles of fatty 

 acids expressed as follows : 



fOH HOO C(CH.)ni CH3 foO C(CHOn, CH, 



CHs <! OH HOO C(CH.,)n. CH,, = C3H5 <[ 00 CfCH^ln, CH3 + 3 H,0 

 LOH HOO CfCHOns CH3 [OO C(CH.,)n,3 CH3 



forming an ester of mixed fatty acids, also called mixed triglyceride. From 



