334 MILK AND MILK PKODUCTS. XIV. 



to the churning and the rapidity with which it has been raised 

 or lowered. Richmond gives the following as most suitable : 



Recently separated cream (quick churning)... 8 C. 



(slow churning) ... 13 C. 



Sour cream (in summer) ... ... ... 13 C. 



(in winter) ... ... ... 18 C. 



Fleischmann recommends 13 for sweet cream, 16 for sour 

 cream. 



If churned at too high or too low a temperature the butter 

 contains a higher proportion of water. According, however, to 

 American experiments, the optimum temperature for churning 

 varies with the breed of cows and also with their food, being 

 higher when cotton seed or cotton- seed meal is used. It 

 seems to be generally admitted that "ripened," i.e., sour, 

 cream, gives a higher yield of butter and churns more readily 

 than sweet cream. 



Opinions greatly differ as to the relative quality of butter 

 from sweet and from ripened cream, but it is generally agreed 

 that the best flavour and aroma in butter can only be obtained 

 from the use of properly ripened cream (v. infra), though 

 disagreeable flavours are also liable to be produced owing to 

 the products of undesirable micro-organisms. Moreover, if the 

 cream be very sour, and especially if it be sour before removal 

 from the milk, the resulting butter will contain a large amount 

 of casein, and on this account probably will more readily 

 become rancid. 



Salt is usually added to butter both as a condiment and also 

 to check decomposition. The amount used varies greatly, 

 from a mere trace up to 7 % being found. 



It is difficult to give any average composition of such a 

 variable product ; usually it varies between the following 

 limits : 



Fat ... ... ... 78-0 to 94-0 



Water ... ... 5-0 to 16-0 



Casein ... ... 0-5 to 3-0 



Ash ... ... ... 0-1 to 4-0 



Sugar ... ... 0-2 to 0-7 



