PASTEURIZATION OF MILK AND CREAM 109 
Next is the heavy line marked with crosses, which 
indicates the time and temperature at which the cream 
line becomes affected. Thus it will be seen that one 
minute’s exposure at 155° affects the cream line. At 
145° the cream line does not become affected until ex- 
posed for 35 minutes. 
The balance of the chart indicates the time and tem- ~ 
perature at which some of the common disease pro- 
ducing bacteria are destroyed. Most resistant of the 
disease bacteria is the tubercle bacillus whose thermal 
death point is shown by the heavy line marked like a 
railroad track. An exposure of one minute at 176°, or 
20 minutes at 140°, will kill this bacillus. The typhoid 
bacillus is destroyed at an exposure of 150° for one 
minute, or 140° for ten minutes. Streptococci 
and the bacteria causing diphtheria are both destroyed 
by heating for one minute at 150°; an exposure of 10 
minutes will destroy both at less than 140°. 
The two parallel light lines marked “red line” and 
running midway between the two heavy dark lines, in- 
dicate the line of safety in pasteurizing milk and cream, 
Going much below this line will not kill the tubercle 
bacillus and going much above it will affect the cream 
line. 
Dr. North properly draws the conclusion from this 
table that a temperature of 145° maintained for 25 
minutes is about the most ideal. ; 
Other Considerations in Pasteurization. While the 
foregoing chart, together with what has been said in 
regard to the lack of uniformity of heating, clearly con- 
demns the “flash” process as an unsafe and undesirable 
method of treating milk, there is another matter to con- 
sider which makes the “flash” process seem still more 
