DAIRYING 



undoubtedly have a uniformly good flavor. Other kinds of 

 bacteria may also be beneficial for cream ripening, but little 

 definite information on this point is available at the present 

 time. Besides the beneficial and the indifferent bacteria, there 

 are other kinds which are directly responsible for defects in 

 butter, among these are the "digesters" and the "gas producers." 

 These may be present in such large numbers as to control the 

 fermentation of the cream and overcome the growth of those 

 bacteria which produce its normal souring. The buttermaker 

 should therefore make an effort to suppress the injurious bac- 

 teria and cultivate the beneficial ones. In order to do this suc- 

 cessfully an acquaintance with the conditions both favorable and 

 unfavorable to the growth of bacteria will be helpful. It is not, 

 however, the purpose of this description to discuss the subject 

 of bacteriology, but simply to give brief directions for the dairy- 

 man to follow in making a starter. 



529. In order to get good results in starter making, a butter 

 maker should understand that bacteria are microscopic forms of 

 life which are present nearly everywhere. The air of the barn 

 and dairy is full of them, and the milk utensil-s, which have not 

 been heated to the temperature of boiling water are "lined" with 

 germs. It is also claimed that 50,000 germs have been found on 

 one house fly. Bacteria multiply very rapidly and cause milk or 

 cream to sour by changing the milk sugar into lactic acid ; some 

 bacteria produce what are called spores and others do not. 

 These spores are not so easily destroyed ; it being necessary to 

 repeatedly or continuously heat milk containing some kinds of 

 spores in order to kill them. Spore-bearing bacteria are usually 

 most plentiful around dirty barns and other filthy places ; they 

 are the cause of a great many defects in dairy products. It is 

 necessary, therefore, in preparing skim milk for starter making, 

 to heat the milk to a high temperature, near the boiling point, 

 for one-half hour or more, in order to kill the spore-bearing bac- 

 teria present, which if not destroyed will grow and spoil the 

 starter. The effect of the putrifactive and other objectionable 

 products formed by the spore-producing bacteria may be largely 

 neutralized by getting the acid-forming bacteria to grow in the 



