TEMPERATUEE CHANGES EST CANNING FEUITS AND VEGETABLES. 



31 



^70 



'O. 





Figure 31 shows the record of cooling for a No. 2 tin can in 

 air and in water. The cooling in air is considerably slower than that 

 of string beans, but the 

 differences are not so 

 great as might be ex- 

 pected from the differ- 

 ences in the rise in tem- 

 perature. The cooling in 

 water, a 1 1 h o u g h v e r 3^ 

 much faster than the cool- 

 ing in air, is still verj- 

 slow in comparison to the 

 cooling of string beans in 

 water. It requires about 

 1 hour and 20 minutes for 

 the corn to fall to 30° C. 

 in these tests, whereas 

 string beans required only 

 10 to 15 minutes. These 

 differences in the rate of 

 cooling in air and in 

 water. It required about 

 tremely important when it 

 is remembered that high 

 temperatures seriously affect the appearance and flavor of the corn. 

 Attention is again called to the fact that when the steam is cut 



off at the end of the 

 processing* period the 

 temperature of the 

 jars falls from any 

 t em pe ra 1 1 1 re above 

 100^ to 100° C. as 

 rapidly as the tem- 

 l)erature in the re- 

 tort. This is impor- 

 tant, especiall}'^ in 

 substances like corn, 

 as sterilizing tem- 

 peratures aiv main- 

 tained for much 

 shorter periods than 

 in tiglitly sealed 

 cans. 



20 30 00 SO 60 70 SO 90 'OO 110 'SO 



r/Af£ m Mi/vures 

 Fig. 33. — Timc-terupcrature relations for sweet corn 

 (Maine stylo) when processed in pint glass jars 

 at 100°, 109°, 116°, and 121° C. These curves 

 were plotted from temperature readings made at 

 intervals of "i minutes. Rise in temperature when 

 proe(<ssed : A, At 100° C. (the proportion of corn 

 to liquor in this case, unfortunately, was less than 

 iu those processed at the higher temperatures) ; 

 B, at 109° C. ; C, at 116° C. ; D, at 121° C. 





10 zo JO 10 so 



Tiue IN MINUTES 



go so jOO I/O tiO 'JO '■to 



Fl(!. 



34. — Time-temperature relntious lur sweet corn 

 (Maine style) when processed iu t|u.irt glass jars at 

 100°, 109°, 116°, and 121° C. Th.-se curves were 

 plotted from leniperature readings made at intervals 

 of 5 minutes. Rise in temperature when processed: 

 A, At 100° C. (the proportion of corn to liquor in this 

 cas(\ unfortunately, was less than \\\ those processed 

 at tho higher tc-mperatures) : /;. it 109° C. ; C, at 

 116° C. ; D, at 121° C. 



VARIETAL DIFFERENCES. 



Other tests were 

 m a d e to determine 



