600 MILK 



Chemical analyses of butter have given the following com- 

 position : 



Thompson, Shaw, Lee and 



and Norton. Bamhart. 



Per cent. Per cent. 



Fat 82.41 83.20 



Water 13-90 13.54 



Salt 2.51 2.25 



Curd 1.18 0-9 



Of course, these figures are average ones. There is consider- 

 able variation in the composition of market butter, especially in 

 the moisture content. Butter makers aim to incorporate as much 

 water as the law permits— 16 per cent.— but must exercise judg- 

 ment, since the moisture is not evenly distributed and may exceed 

 the legal hmit in some places. Soft butter retains water in greater 

 measure than hard butter. Raw cream butter usually contains 

 more water than butter made from pasteurized cream; large 

 churnings and those at high temperature have a similar effect. 

 During storage some of the moisture is lost, more- from salted 

 butter than from sweet butter. 



The mineral content of butter varies considerably, depending 

 largely upon the amount of salt worked into it. The object of 

 adding salt to butter is chiefly to render it more resistant to de- 

 composition, and incidentally the salt covers up off-flavors to a 

 limited extent. The presence of salt, fm-thermore, adds to the 

 palatability of the butter. The amount of salt added varies up 

 to 5 per cent. 



Although it is possible to make butter from milk, by far the 

 largest amount is made from cream. Cream churns more easily 

 than milk; in fact, the richer the cream, the more readily does it 

 churn. 



Cream is separated from milk in one of two ways: either by 

 gravity — this is gravity cream — or by means of a centrifugal 

 separator. 



Gravity cream is obtained either by the "shallow pan sys- 

 tem" or by the "deep-setting system." In the former case the 

 milk is placed in pans 2 to 4 inches deep and kept at 60° F. in 

 pure air to avoid bacterial contamination as far as possible. 

 The cream is finally skimmed off, leaving a skimmed milk con- 

 taining from 0.5 to 1 per cent. fat. Better results are obtained 

 by the deep-setting system. Four-gallon shotgun cans, or spe- 

 cially constructed cans with a piece of glass to observe the cream 

 hne, are filled with milk and kept at 55° F. or lower. The cream 

 separates in about twenty-four hours and is then skimmed off, 

 or the skimmed milk is removed if the can is provided with a faucet 

 at the bottom. This skimmed milk may contain as little as 0.2 

 per cent. fat. 



