88 GUIDE TO DAIRYING IN SOUTH AFRICA 



below 3 per cent, or rise to 6 per cent, or more. 

 The first milk drawn from the cow may register as 

 low as 0*5 per cent, while the strippings may go as 

 high as 10 per cent. The " solids not fat " are not 

 liable to such variation. 



Milk fat is held in suspension in the form of 

 tiny fatty globules so small that 100 to 150 million 

 are present in a single drop of milk. The size of 

 the fat globule varies with the breed the Jersey 

 giving the largest fat globule and the Ayrshire 

 giving the smallest. It was at one time thought 

 that these globules were enclosed in a membrane, 

 and that in churning the membrane would have to 

 be broken before the globules would unite together, 

 but this is not the case, for no membrane exists. 

 The form and individuality of the globules is main- 

 tained by surface tension which, pressure being 

 equal on all sides, causes the globules to assume a 

 spherical shape. Milk fat is really a mechanical 

 mixture of a number of different fats, and the physical 

 properties of butter to be made from it are largely de- 

 pendent upon the proportion in which these fats are 

 present. The composition of milk fat is as follows : 



Butyrin . 6 per cent. \ 



Caprin . 



Caproin 



Caprillin 



Laurin . 

 Stearin . 

 Palmitin 

 Myristin 

 Olein 



Milk fat. 



5 



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