TEMPERATURE CHANGES IN CANNING FRUITS AND VEGETABLES. 23 



Stirring the material during processing is of no advantage, be- 

 cause there is no difficulty in getting the heat to the center of the can. 



It must be remembered also that the cooling is much faster in air 

 than in the retort. If the cans are left packed in the retort to cool, 

 the temperature may remain above 100° C. for 1 hour or longer. 

 If the processing has been sufficient, a rapid cooling is of advantage, 



/30 



//o 

 /od 

 so 



ft 

 ^60 



SO 



to 



eo 



P 



/O 2.0 SO *K> SO 

 T/Af£ //V M//VUTES 



eo 



Fig. 16. — Time-temperature relations for 

 peas in 2 per cent brine when proc- 

 essed in No. 3 tin cans at 100°, 109°, 

 116°, and 121° C. These curves were 

 plotted from temperature readings at 

 intervals of § minute and 1 minute. 

 Rise in temperature when processed : 

 A, At 100° C. ; B, at 109° C. ; C, at 

 116 e C. ; B, at 121° C. 



/SO 



/eo 

 //o 

 /oo 



90 



SO 



1° 



\ 



SO 



<?o 



30 



2 °o 



T/ME /N M/NOTES 

 Fig. 17. — Time-temperature re- 

 lations for peas in 2 per cent 

 brine when processed in pint 

 glass jars at 100°, 109°, 

 116°, and 121° C. These 

 curves were plotted from 

 temperature readings made 

 at intervals of 1 minute 

 and 1 minute. Rise in tem- 

 perature when processed : 

 A, At 100° C. ; B, at 109° C. ; 

 O, at 116°, C. ; D, at 121° C. 





because the high temperature continues to alter the flavor and quality 

 of the product. 



Here, again, the temperature records shown are for the liquid fill- 

 ing the spaces between the peas, no attempt being made to measure 

 the temperature within the peas themselves. This could have been 

 done with suitable thermocouples, but it could not take more than a 

 very few minutes for the heat to be conducted from the surrounding 



