222 AERATING OR BLOWING CREAM 



are, therefore, present to a greater extent in intensely fer- 

 mented and sour cream than in cream of good quality and with 

 low acidity. Hence the reduction of the acidity due to pasteur- 

 ization must be greater in cream of poor quality, and especially 

 in yeasty cream, than in cream of good quality and cream that 

 comes fresh and sweet from the separator. 



AERATING OR BLOWING CREAM. 



Purpose. By aeration of cream is understood the inten- 

 tional and systematic exposure of the cream to air. The pur- 

 pose of such aeration is to facilitate the escape from the cream 

 of objectionable volatile substances, gases, that harbor unde- 

 sirable odors and flavors. In short, the object of aeration is 

 to improve the flavor of cream and butter. 



Methods. The aeration may be accomplished in three 

 different manners, i. e. 1. By exposing the cream in a thin 

 layer to the atmospheric air. 2. By blowing air through the 

 cream. 3. By drawing the air and gases out of the cream by 

 suction. 



The first method usually consists of running the hot cream 

 from the pasteurizer over a surface-coil cooler. The cream 

 flowing over the cooler in a very thin film, conies in contact 

 with a relatively large amount of air, facilitating the escape 

 ^of gases and objectionable odors. The heat of the pasteurized 

 cream further enhances the expulsion of these gases. The re- 

 moval of the escaping gases may be further hastened by the 

 installation of a ventilator over the aerator-cooler and the effi- 

 ciency of the ventilator may be augmented by equipping it 

 with a mechanical fan. In this form of aeration, it is important 

 that the atmosphere in which the cream is aerated and to which 

 it is exposed, be free from foul odors and bacterial pollution, 

 otherwise the cream will absorb these odors and become re- 

 contaminated with germ life. 



The second method of aeration, the blowing of air through 

 the cream, is an intensified form of aeration. Its purpose is 

 to not only bring the cream in contact with the maximum 

 amount of air, but to cause this air to blow through the cream 

 and thereby mechanically force the gases out of the cream. 

 The blowing is accomplished by the use of a centrifugal fan. 



