36 BULLETIN 1022, U. S. DEPARTMENT OF AGRICULTURE. 
These curves represent individual tests and hence probably vary 
somewhat from the average. They show how the temperature at the 
center of the can continues to rise after taking from the retort for 
from 5 minutes in the case of the can processed for 90 minutes to 15 
. minutes in the can processed for 30 minutes. They show, further, 
the length of time the corn remains above critical temperatures for 
sterilizing purposes. For instance, the temperature is seen to remain 
above 100° C. for 20 minutes when the processing is continued for 
30 minutes and remains above 100° C. for 95 minutes when processed 
for 90 minutes. These values obviously would be different for curves 
starting at different initial temperatures. The curves give a definite 
idea, however, of the rate and the nature of the temperature changes 
when corn 1s eed for various periods and then air cooled. They 
in value such curves as 
are illustrated in figure 
21 may be, for they area 
record of a continuous 
- processing at a definite 
temperature until the 
temperature of the can 
zo reaches the temperature 
fila ohaaemesnetia 
Ce 
CARA 
5 = a 
TEMPERATURE (N DEGREES CENTIGRADE 
OD p 
° 10 20 30 40 50 60 70 80 90 100 110 
TIME IN MINUTES 
Fig. 23.—Experimental time-temperature curves for : s 
‘‘Maine style’’ corn in No. 2 tin cans, starting at a with corn in actual 
uniform temperature of 80° C., processed for different . i : 
periods of time at 116° C., and cooled in water at practice the jBEU Cos E s 
about 25° C. Proportion of corn to liquor, 4:1. The period 1s less than the 
arrows indicate when cans were taken from the retort 
and put into water. Curve for can processed: A, 
For 30 minutes; B, for 45 minutes; C, for 60 min- can to reach the tem- 
utes; D, for 70 minutes; H,-for 90 minutes. perature of the retort, 
curves such as are shown in figure 21 give an actual record only so 
long as the can is in the retort, but tell nothing beyond that point. 
It is important to have a record of the temperature after the can is 
removed from the retort, which can be obtained best from curves 
made under conditions of actual practice. Since the behavior of the 
temperature of the contents of the can after removal from the retort 
varies with the processing period and with the cooling conditions, it | 
makes the calculation of the record of one processing from another 
of a different length very difficult. 
Figure 23 shows the time temperature curves for No. 2 cans of corn 
starting at 80° C.; processed at 116° for 30, 45, 60, 70, and 90 minutes, 
and then cooled in water. 
When the cans are removed from the retort and placed in cold 
water the rise in temperature is almost immediately stopped and the. 
cooling curves drop rapidly. In corn, therefore, when the cans are 
show how very limited — 
of the retort. Since | 
time necessary for the 
