320 COMPOSITION OF BUTTER 



fat, it is a more difficult problem approximately to control the 

 composition of butter. Churning cream at a high temperature 

 will invariably result in a high moisture-content and will also 

 result in an extreme loss of fat in the buttermilk. 



In churning cream of medium-high fat-content, it is advisable 

 to fill the churn only about half full, to churn at such a low tem- 

 perature that the butter will gather in about forty-five to fifty 

 minutes, and to churn the butter to granules about as large as 

 peas. A small variation in the components of butter affects the 

 quality very little, provided the butter has been properly made 

 and the components properly incorporated. In the same cream- 

 ery the composition of butter varies according to the season of 

 the year, from day to day or even from churning to diurning. 

 According to the present methods of manufacturing, water and 

 salt are the components most likely to vary. Casein will vary very 

 little if the butter is efficiently washed and churned in a condi- 

 tion in which it will gather firm. Normally, casein is estimated 

 at i per cent, occasionally it has been found to run as high as 

 4 per cent. It rarely exceeds 2 per cent, and seldom falls as 

 low as A of i per cent. A high curd-content will show itself in 

 the butter in the form of milky brine or in the form of white 

 specks. If there is less than 2 per cent present, the brine will 

 not be affected. 



One of our large creameries had an average casein con- 

 tent of .65 for a year. This was due to their method of washing 

 their butter a number of times. An excessive amount of casein 

 in butter is supposed to affect its keeping qualities. 



Curd and milk-sugar are incorporated from the milk into 

 the butter during the churning. In the manufacture of butter 

 for storage, these substances should be excluded from the butter 

 as thoroughly as possible. Milk-sugar and albuminoids consti- 

 tute the chief foods for bacterial growth. As deterioration of 

 butter has been demonstrated to be due chiefly to the action 

 of micro-organisms it becomes essential to restrain their growth 

 as much as possible by excluding the food necessary for their 

 growth. 



The average salt-content of butter is about 2\ per cent; 



