BACTERIA IN BUTTER AND OLEOMARGARINE. 



and the greater satisfaction in being able to control the process has 

 caused the wide adoption of starters among butter-makers. 



BACTERIA IN BUTTER. 



Although bacteria continue to grow during the ripening period, 

 their growth is practically stopped by churning and butter-making. 

 Many of them are removed with the butter-milk; others are washed 

 away during the washing and working of the butter. Large 

 numbers are still left in the butter. Ordinarily these bacteria do not 

 grow in the butter, though, if it is not salted, some of them may 

 grow and hasten its spoiling. Unsalted butter does not keep long, 

 and its destruction is largely due to bacteria. But if the butter is 

 salted, as is the rule in most countries, the salt checks the growth of 

 bacteria. As a result of this and the compact condition of the 

 butter, together with its small amount of water, the bacteria do not 

 find butter a favorable medium for growth, and they begin to diminish 

 in numbers. A very few hours' time shows a great reduction in 

 numbers, and this continues until, after a few weeks, the butter con- 

 tains comparatively few. They do not entirely disappear, for some 

 are found even in very old butter. The ordinary species of organ- 

 isms, which have been active agents in the cream-ripening, play no 

 further part in the changes which may occur in the butter. The 

 following figures of the number of bacteria in butter will illustrate 

 the facts. 



No. of Bacteria per Gram of Butter. 



Two hours old. One day old. Four days old. Thirty days old. 

 ' 54,000,000 26,006,000 2,000,000 300,000. 



It is well known that, if butter is not used immediately, certain 

 changes occur in it which continue slowly for many weeks. The 

 butter retains its fresh, delicate flavor and aroma for only a few 

 days; but if it is kept cool and away from the light, it may remain 

 sweet and good for many months. If, however, it is not kept very 

 cold, further changes soon begin to appear which slowly progress 

 and eventually ruin the butter. The most noticeable feature 

 is the appearance of rancidity. This change is accompanied by the 



