40 



BULLETIN 956, U. S. DEPARTMENT OE AGRICULTXJEE. 



it requires about 1 hour and 30 minutes to approach the temperature 

 of the bath. At 109° C. it requires about 1 hour and 20 minutes, 



/30 

















O 































/ 



^ 









C 



' 















































/OO 



S3- 



60 

 ■50 

 ^O 

 JO 

 20^ 











/ 





^^ 



J^ 





























1 



/ 



/ 



^ 





/?, 





































/ 



1 



/ 



y 



^ 



^' 































/ 



/ 



/ 



































/j 



V 



































J 



/ 



































/ 



/ 



/ 

































1 



L 



1/ 



































Uf 





































■} n 



7 £ 



V ^ 



O 'H 



7 <S 



&. 



? 7< 



7 3 



7 Si 

 T/Mt 



/C 





O /so /30 /'^O /SO /60 /■P'O /BO I90 



Fig. 46. — Time-temperature relations for tomatoes wheu processed in Ko. 3 tin cans at 

 100°, 109°, 116°, and 121° C. These curves wore plotted from readings made at 

 intervals of 5 minutes. Rise in temperature when processed : A, At 100° C. ; B, at 

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



at 116° about 1 hour and 10 minutes, and at 121° it requires 1 hour 

 to reach the processing temperature in a No. 2 tin can. Similar 



results are noticed in the No. 

 3 tin cans and in tlie pint and 

 quart glass jars. A shorter 

 time is required to reach the 

 temperature of the retort at 

 121° than at any lower proc- 

 essing temperature. With 

 many vegetables and fruits 

 there is a slowing down in 

 the rate of rise as the tem- 

 perature goes higher, owing 

 to the going into solution of 

 starch, protein, or other ma- 

 terial, which changes the vis- 

 cosity of the material. This 

 change in viscosity interferes 

 with convection, and so the 

 process is slowed clown. A 

 change of exactly the oppo- 

 site character is taking place 

 in the tomato. The tomato 

 fruit is very succulent, and 

 its tissues are easily broken 

 down at high tempera- 



/so 

 /so 





























/■ 



/^ 









//o 















4 



-/" 



•^ 



^^ 







so 

 ""so 



\- 



,50 

 .30 



eo 







/ 



f 



/^ 



'2^ 



' 











1 



// 



V 















k 



Y 















/ 



1 

















/ 



f 

















// 

















J 



/ 

















^ 



7 



































'/ /c 



-> 2 



S 



'PC 

 T/M£. 



//V A- 



6C 



r//vu7 



? 7C 



? sc 



? 30 



Fig. 47. — Time-temperature relations for to- 

 matoes when processed in pint glass jars 

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

 were plotted from readings made at intervals 

 of 5 minutes. Rise in temperature when 

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

 C, at 116° C. ; D, at 121° C. 



