224 AERATING OR BLOWING CREAM 



the oxidation of one or more of the constituents of cream and 

 butter. Atmospheric air is an active oxidizing agent. Its 

 presence in cream and in butter, hastens deterioration, and the 

 greater the amount of air present, the more rapid and the 

 more intense the destructive action. 



To run the hot cream over a surface coil cooler, where it 

 is freely exposed to the air, is detrimental to the keeping qual- 

 ity of the resulting butter. The damaging action of the air in 

 this case is greatly intensified by the heat of the cream, and 

 the copper of the aerator over which the cream flows. Heat 

 alone enhances all forms of oxidation. The heat and acid of 

 the cream act on the copper and copper is a most active oxi- 

 dizer and catalizer. Even very minute quantities of copper 

 salts in butter, resulting from the action of hot, slightly sour 

 cream in the presence of air, have a very intense deteriorating 

 effect on the butter. 



To blow air into and through the cream obviously in- 

 fluences the keeping quality in a similar unfavorable manner, 

 and if the cream is blown while hot, the action is correspond- 

 ingly greater. The blowing of cream, therefore, is -a very 

 questionable expedient, as a means to improve the permanent 

 flavor of the butter. 



These facts can leave but little doubt that, while surface 

 aeration and blowing do temporarily improve the flavor of 

 cream and of butter, they are positively dangerous to the keep- 

 ing quality of butter, and since keeping quality is the crucial 

 and final criterion of butter acceptable to the trade, these forms 

 of aeration cannot be recommended as beneficial processes in 

 the manufacture of butter. 



The drawing of air out of the cream, on the other hand, 

 has distinct merits, as far as it is practicable. It not only 

 improves its flavor, but it assists in removing from cream one 

 of the destructive agents air and thereby tends to enhance 

 the stability of the finished product. 



If it were mechanically and economically feasible to handle 

 the cream and to manufacture the butter under reduced pres- 

 sure, in a partial vacuum, the keeping quality of butter would 

 be greatly benefitted and such a process of so-called aeration 

 might logically be looked upon as the last word on ideal butter 

 manufacture. 



