BUTTER DEFECTS 477 



13. Store the butter in a clean, dry room and keep the 

 temperature as low as possible. Molds grow best in a moist 

 atmosphere and at a temperature around 50 to 60 F. 



14. Make the butter from cream of low acidity (.3% acid 

 or below). Molds prefer an acid medium for growth. 



15. Keep the air in the creamery well ventilated and the 

 sewers and floors well scrubbed. A stagnant, impure atmo- 

 sphere is often pregnant with mold spores. 



16. Spray the walls, ceilings and floors of butter storage 

 rooms with formaldehyde, at reasonable intervals. Do not per- 

 mit the appearance of mold specks on walls and ceilings. 



For additional directions for the treatment of liners and 

 wrappers see Chapter XII on ''Packing Butter." 



Yeasty Flavor and Foamy Cream. This flavor is the re- 

 sult of a yeast fermentation of the cream. It is most preva- 

 lent in summer, particularly during the hottest summer weather, 

 when both, the days and the nights are hot and when the cream 

 is exposed to the summer heat for a considerable length of 

 time. Yeasty flavored butter seldom scores better than a "Sec- 

 ond." It represents a very objectionable flavor defect which 

 no now-known process of manufacture is capable of entirely 

 removing. Nor does it disappear while the butter is held in 

 cold storage. This flavor stays in butter until the butter is 

 consumed. 



Yeasty cream, therefore, should be culled out at the cream- 

 ery by rigid grading, and churned separately, if it is accepted 

 at all. The adoption and practice of an efficient system of cream 

 grading and paying on the basis of quality is the creamery's 

 most effective immediate weapon to minimize receipts of yeasty 

 cream, accompanied by a systematic effort to acquaint the 

 farmer with the fact that the reason why he received a lower 

 price was that the cream was yeasty, and by instructions of 

 how to best avoid the recurrence of this defect. 



The fundamental cause of yeasty and foamy cream lies in 

 the presence in cream of yeast cells. Most, if not all, cream 

 contains some yeast cells, but at moderate or low temperatures 

 they fail to gain the ascendency and therefore do not develop 

 a yeasty flavor in the cream nor cause the cream to foam. 



