26 BULLETIN 240, U. S. DEPARTMENT OF AGRICULTURE. 



2. Bottles should be steamed at least two minutes before being 

 filled with milk in order to destroy heat-resistant types of organisms 

 which might survive the pasteurizing temperature and thereby in- 

 crease the bacterial count. 



3. Care must be taken to record the temperature in the bottom of 

 the bottle during the heating process. When milk at an initial 

 temperature of 50° F. is heated in bottles without agitation in water 

 at about 146° F. the temperature of the milk in the top of the 

 bottle will reach 140° F. about nine minutes before that in the bot- 

 tom. The temperature of the milk during the process of pasteuriz- 

 ing in the bottle should be recorded by placing a thermometer in a 

 control bottle with the bulb of the thermometer about one-half inch 

 from the bottom. The milk should be heated for 30 minutes at 

 145° F. 



4. When bottles are heated and cooled under water care should 

 be taken not to use bottles with chipped or otherwise imperfect tops, 

 since the seal caps may allow leaks during the process of pasteuriz- 

 ing. It is advisable for the users of patented seal caps to assure 

 themselves that the caps are water-tight, since leaking caps may 

 cause dangerous infections, particularly if the cooling water is pol- 

 luted. 



5. The process of bottling pasteurized milk while hot in hot 

 steamed bottles causes equally good bacterial reductions as does 

 pasteurization in bottles. .Even with the same length of exposure 

 of 30 minutes and the same temperature of 145° F. the bacterial 

 reductions are often much greater than those produced by pas- 

 teurization in bottles. 



6. In the process of bottling hot, bottle infection is eliminated, 

 even when several cubic centimeters of old, sour milk are added to 

 bottles before filling. The two-minute steaming period to which 

 the bottles are subjected before filling with hot milk is sufficient to 

 destroy the contamination, at least so far as bacteriological methods 

 can detect. 



7. Laboratory experiments indicate that milk may be pasteurized, 

 bottled hot, capped with ordinary cardboard caps, and cooled by a 

 blast of cold air. 



8. It is probable that if milk is cooled from 145° to 50° F. within 

 five hours no more bacterial increase will take place during the slow 

 cooling than would take place if the milk were cooled immediately 

 to 50° F. Whether or not this will be true under commercial con- 

 ditions can be determined only by future experiments. 



9. So far as the laboratory experiments indicate, when milk is 

 heated to 145° F. for 30 minutes, the bottling of the hot pasteurized 

 milk followed by slow, gradual cooling has no more appreciable 



