J52 STATE BOARD OF AGEICULTURE 



The variations in temperaturo of Tvater and milk corresponded exactly witli 

 tlie two previous cases. Tlie following lessons may be drawn from the above 

 experiments: 



1. Any method which is controlled entirely by the temperature of the Avater is 

 iinreliable. 



2. Any method whicli allows the water and milk to stand for twenty minutes 

 Avhen the water has reached 68° C, without further application of heat, is varia- 

 ble and uncertain. 



3. Tlie temperature of the water is no indication of the temperature of the 

 milk, and the only way safety can be guaranteed by the temperature of the 

 water is to heat the water to a sufficiently high degree to render the temperature 

 of the milk safe beyond doubt. 



4. There is much variation in the temperature of unstirred water or milk. 

 Milk should be stirred when pasteurized at 68° C. {155°F.) 



Manv do not dislike the cooked flavor and odor which is produced when milk is 

 heated' above 70° C. (158° F.), and they always heat the milk to a higher point 

 than that discussed in this bulletin. The lactalbumin is easily coagulated and 

 the casein may be rendered less responsive to rennet, thus making the action of 

 the pepsin and pancreatin less effective. With many children, this chemical 

 change of the milk would pass unnoticed, but with others it would work apparent 

 injury. If due care is taken in the preparation and modification of the milk, it 

 maybe that the latter class would be somewhat reduced. Should harm result 

 from the heating of the milk to a high temperature, the pasteurization ought to 

 be carried out at G8° C. (155° F.). 



In case the heating of milk to a high temperature does not injure or prove 

 objectionable, a much easier method of pasteurization may be resorted to. To 

 establish some standard to follow whicu will yield good results, a few experiments 

 have been undertaken. Experiment 1: A vessel is placed on the stove with a pie 

 tin in the bottom. Upon this are placed bottles of small diameter filled with milk 

 and plugged with cotton wool. The water in the vessel should equal the height 

 of the milk in the bottles. This method of preparation is practically that recom- 

 mended by Dr. Schweiuitz. The water in the pail or vessel is heated to the boil- 

 ing point," the heat removed and the milk and water allowed to stand for thirty 

 minutes, at tlie end of which time it is cooled. 



To test this method, milk artificially infected with tuberculous material was 

 used. 



Guinea pigs, Nos. 256 and 266 were inoculated intra-abdominally with 1 c. c. 

 each of the milk before it was pasteurized as above. 



Both of these animals developed general tuberculosis in a few- weeks. 



Guinea pigs, Nos. 267 and 268, from bottle 1; 269 and 270, from bottle 2: and 

 271 and 272, from bottle 3; were inoculated intra-abdominally with 5 c. c. each 

 after the milk had been pasteurized. 



No traces of tuberculosis could be found in any of these when they were chloro- 

 formed at the time the controls 256 and 266 were examined. 



Experiment 2. The same apparatus was used as in experiment one and handled 

 (except the heating) in the same way. This lot was heated to the boiling point, 

 held there for five minutes, then cooled. 



