COMPOSITION OF BUTTER-FAT 



15 



fats, the fats with a low melting-point would melt first, and leave 

 the remainder in an unmelted condition. Such is not the case. 

 Butter-fat in this respect behaves a good deal like different 

 metals with different fusing-points. When they are melted and 

 mixed together, cooled and then remelted they assume a common 

 melting-point. Butter-fat behaves in the same way. It melts 

 at a temperature of 91 to 96 F. 



As the body temperature of cows (about 101 F.) is above this 

 temperature, the fat globules are present in the milk in liquid 

 form when it is first drawn. A peculiarity about these fat- 

 globules in milk is that the milk and fat may be cooled below the 

 melting-point of the fat of butter without the fat-globules in milk 

 being solidified. It requires a temperature of between 60 and 

 78 F. before the fat-globules in milk begin to solidify. When 

 these small fat-globules are caused to unite, as during the churning 

 process, they solidify at a higher temperature. This behavior of 

 the fat in milk evidently must be due to a relative change in the 

 position of the molecules of fat during the process of cooling and 

 warming. No definite explanations, so far as is known, have been 

 given for this condition of the fat. 



The non-volatile fats found in butter-fat are practically the 

 same as those found in other animal fats. 



Composition of Butter-fat. In his " Dairy Chemistry," 

 Richmond gives the following composition of butter-fat, repre- 

 senting the mean results obtained by different observers: 



Per Cent 



( Butyrin 3 . 85 



8 per cent volatile \ Caproin 3 . 60 



{ Caprylin 55 



Fat.. 



92 per cent non-volatile. 



Caprin 1.9 



Laurin 7.4 



Myristin 20 . 2 



Palmitin 25.7 



Stearin 1.8 



Olein 35 



Richmond also gives the percentage of glycerine and fatty 

 acids in each of the different fats, as follows: 



