328 THE CHEMISTRY OF DAIRYING 



It has been shown (p. 322) that one sample of so-called 

 cream may contain four times as much fat as another. It is 

 obvious that the products prepared from substances which 

 differ so widely in composition cannot be even approximately 

 similar if not controlled in some way. When cream is 

 separated by the centrifugal apparatus, the percentage of fat 

 can be regulated within certain limits. The percentage of fat 

 can be easily estimated, and, if necessary, the cream can be 

 diluted with milk to a standard strength. 



The composition of whole milk is not nearly so variable 

 (p. 288), but it may easily happen that one sample contains 

 from 25 to 50 per cent, more fat than another. When cream 

 is added to whole milk it is impossible to obtain a uniform 

 product unless the composition of both is known, and the 

 quantities are duly adjusted. It is still more difficult to attain 

 uniformity by any process which consists in abstracting a 

 portion of the cream. The term skim milk cheese is rightly 

 applied to samples made from milk from which any part of 

 the fat has been removed ; but it is perhaps more frequently 

 applied to cheese made from separated milk which is practi- 

 cally devoid of fat. Such cheese is, however, somewhat 

 unpalatable, and is now rarely made in this country. Some- 

 times the separated milk is made into margarine cheese by 

 admixture of non-butter fats. 



Ordinarily, cheeses are divided into hard and soft kinds. 

 The latter includes the cream cheeses which are characterised 

 by the presence of a high percentage of fat. The ratio of fat 

 to casein in cream cheese is commonly about 10 or 12 to i ; 

 but in some cases it is as high as 25 to i, and in others less 

 than 2 to i. A ratio of 2 of fat to i of casein is often found 

 in other cheeses both hard and soft. The soft cheeses not 

 made from cream are characterised by a relatively large pro- 

 portion of water. In general they contain about 50 per cent, 

 or more of that ingredient, whereas hard cheeses as a rule 

 contain only from about 30 to 40 per cent, of water. The 

 cheeses made from partially skimmed milk are mostly of the 

 hard variety, but some, e.g. " York," are soft. In such skim- 

 milk cheeses the ratio of fat to casein is generally somewhat 



