MILK AS A FOOD 37 



The first milk drawn from the udder is commonly poor 

 in fat. This is known as "fore milk." The middle portion 

 contains about the average percentage of fat, and the last, 

 known as '* strippings," is always richest in fat. The stripe- 

 pings may contain as much as nine or ten per cent of fat 

 while the average milk contains but four per cent. The 

 reason that the fore milk is poorer in fat than the strippings 

 was formerly supposed to be due to the fact that the fat 

 rises in the milk stored in the cisterns of the udder, but is 

 probably accounted for by the fact that the fat sticks to the 

 sides of the ducts. Hence the method of milking by man- 

 ipulating the udder at the end of the flow secures an extra 

 quantity of fat. 



The cream layer is influenced by a number of factors. 

 It may be destroyed by heat, agitation, and other agencies. 

 As the cream line is one of the principal things that the 

 householder looks for, the dairyman is very careful not to 

 heat the milk too high in pasteurizing, and also guards 

 against undue agitation, both of which tend to destroy 

 this apparent evidence of richness. The richness of milk, 

 however, cannot be judged by the depth of the cream line. 

 There are several factors, not the least of which is the 

 narrow neck and thickness of the milk bottle, which gives 

 an exaggerated notion of the amount of cream. 



The cream does not always rise well in rich milk, even 

 after standing more than twenty-four hours. The large fat 

 droplets rise first and the very smallest may not rise at all. 

 A watered milk throws up its fat more quickly than a 

 normal specimen, although it does not contain as much. It 

 appears therefore that a milk of inferior grade may show a 

 deeper cream layer than a milk of unusual richness. Gen- 

 erally speaking, however, a rich milk will usually show its 

 quality on standing. 



The fat does not rise well upon heated milk. Milk may 

 be heated to 145 F. for one hour without markedly influ- 

 encing the cream line. If the milk is heated somewhat 



