TREATMENT OF CKEAM PREVIOUS TO THE CHURNING. 227 



ripening, since the time during which the cream may be 

 infected with bacteria is thus only increased. 



In rapid ripening greater watchfulness is necessary 

 and the progress of the fermentation must be repeatedly 

 examined, for the rapidity of the process greatly increases 

 the danger of its progressing too far. It may be added, 

 that if the cream turns too acid, lumps of casein will sepa- 

 rate out and later on be taken up by the butter, which will 

 then not keep well, casein, as is well known, being very un- 

 stable and easily attacked by putrefactive bacteria. When 

 ripe for churning, the cream should not contain any sepa- 

 rated lumps of casein. 



The cream must not, on the other hand, be ripened too 

 little, as the taste will then not be as desired; the souring 

 will continue in the butter and will there take place under 

 wholly new conditions, the regulation of which we have 

 not in our power. A good acidity, not too mild and not 

 too strong, is most desirable for the production of a well- 

 keeping butter.* 



* It would be of great advantage to butter-makers, and more 

 especially to novices among them, to possess a method by which the 

 proper acidity of the cream could be accurately determined. In 

 laboratory- work and in investigations conducted by dairy chemists 

 the method of titration of the cream by means of an alkali has long 

 been practised, but it was not adapted to factory purposes in our 

 country until 1890, when Dr. Manns published (Bull. 9, 111. Exp. 

 Station) what is known as Manns' Acid Test. The method rests on the 

 principle that the compound phenol phtalein gives an intensely red 

 color to alkaline solutions ; a solution of an alkali (either potash, soda, 

 lime, or baryta may be used) of known strength is added until the 

 liquid assumes a permanent red color, and the acidity of the cream can 

 then be calculated. The description of the Manns test is given as 

 follows : 



Directions for the Use of Manns' Test: I. Stir the cream thor- 



