THE PASTEURIZATION OF MILK 



full of dust or foul odors. In most milk plants, 

 however, the air is so moist that little dust is flying 

 about, and recent investigations by Ruehle and 

 Kulp * of milk contamination by stable air indi- 

 cate that even under unfavorable conditions the air 

 contamination is not as serious a matter as we have 

 supposed. Of course, milk coolers can be en- 

 closed by tightly fitting metal covers, or they may 

 be located in separate rooms or compartments, and 

 so be protected from contact with air which is 

 questionable. If a separate room is provided, 

 suitable ventilation should be secured for carrying 

 off steam, and the opening for the admission of air 

 should be so protected that the incoming air will 

 be filtered. 



Since it is difficult to clean and sterilize metal 

 covers for coolers, it seems more desirable that the 

 milk be protected by enclosure in separate rooms. 



The complete sterilization of this open type of 

 cooler is a rather difficult matter. The reason for 

 this is that the cooling surface cannot be subjected 

 to the action of steam under pressure. The usual 

 method employed is to direct live steam from a 



*Bul. 409. N. Y. Agricul. Exp. Sta. 

 158 



