20 



BULLETIN 202, TJ. S. DEPARTMENT OF AGRICULTURE. 



EFFECT OF HOLDING THE MILK AT DIFFERENT TEMPERATURES. 



The temperature at which the milk is held would, of course, 

 affect the length of time before the alcohol test becomes positive. 

 To show the effect of temperature we held samples of raw and pas- 

 teurized milk at 9° C. and also at room temperature, and examined 

 them in the same manner as in the preceding experiment. The 

 results are shown in Table 16. In order to have about the same 

 bacterial content in the milk held at the different temperatures, a 

 quart of milk was thoroughly mixed and placed in sterilized pint 

 bottles. 



The results show clearly that the temperature at which milk is held 

 has a marked influence on the time when the alcohol test will be posi- 

 tive. Also, as shown by sample of raw milk C, the bacterial content 

 of the milk is an important factor. In all the samples it will be no- 

 ticed that the bacterial counts show an exceedingly high number 

 when the 68 per cent alcohol test was positive. 



Table 16! — Comparison of the alcohol tests with milk held at 9° C. and at 24° C 



Temper- 

 ature at 

 which 

 held. 



Days 

 held. 



Raw milk A. 



Pasteurized milk B. 



Acid- 

 ity. 



Alcohol test. 



Bacteria per 

 cubic centi- 

 meter. 



Acid- 

 ity. 



Alcohol test. 



Bacteria per 

 cubic centi- 

 meter. 



75 

 per 



cent. 



68 

 per 



cent. 



44 

 per 



cent. 



75 

 per 

 cent. 



68 

 per 



cent. 



44 

 per 

 cent. 



9°C... 



Room 

 tem- 

 pera- 

 ture 12 







1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



17 







l(9a.m.) 

 l(3p.m.) 



1.85 

 1.85 

 1.90 

 1.80 

 1.79 



- 



- 



= 



1,600 



1.65 

 1.60 

 1.60 

 1.70 

 1.71 



= 



= 



- 



139,000 



















1.85 

 1.90 

 1.80 



1.80 



= 



= 



= 





1.60 

 1.80 

 1.65 



! + S 



— 



- 



















1.72 

 2.00 







197,000,000 





2.70 

 4.1 



1.85 

 1.90 

 3.1 



+L 

 +L 



+ L 



+M 



+L 



+L 



+L 

 + L 



400,000,000 



2.3 



+L 



+M 



- 



960,000,000 



440,000,000 

 2,900 



4.3 



1.65 

 1.85 

 3.70 



+L 



+s 



+L 



+ L 



+L 

 + L 





146,000 

 32,600,000 

 694,000,000 



534,000,000 



1 See footnote under Table 1. 



2 About 24° C. 



