Bacteria in Sutler-Making. 147 



that of machine oil, a peculiarity that is transmitted 

 directly to butter made from affected cream. 



152. Bitter butter. Now and then butter develops a 

 bitter taste that may be due to a variety of different bac- 

 terial forms. In most cases, the bitter flavor in the butter 

 is derived primarily from the bacteria present in the 

 cream or milk. Several of the fermentations of this 

 character in milk are also to be found in butter. In ad- 

 dition to these defects produced by a biological cause, 

 bitter flavors in butter are sometimes produced by the 

 milk being impregnated with volatile, bitter substances 

 derived from weeds. 



153. Moldy butter. This serious defect in butter is 

 caused by the development of the common mold fungus 

 (Penicillmm glaucum) on the inside of butter packages. 

 Where tubs are made from green, sappy wood, the mold- 

 spores that are practically everywhere, find favorable 

 conditions for growth, especially, where moisture exists. 

 The result is that as the wood molds, the outer layers 

 of the butter are stained and at the same time acquire 

 a moldy taste. This defect can be easily obviated by 

 steaming the tubs thoroughly before packing. Butter 

 tubs should always be kept in a cool, dry place under 

 conditions unfavorable for the growth of the mold-spores. 



