. A study of the factors affecting temperature changes in the container during the canning of fruits and vegetables . 100°, 109°, 116°, and 121° C. These curves were plotted from read- ^aac atintervals of 5 minutes. Rise in temperature when processed : A, A ^00° C. ; B, at109° C. ; C, at 116° C. ; D, at 121° C. at 116° about 1 hour and 10 minutes, and at 121° it requires 1 hourto reach the processing temperature in a No. 2 tin can. Similar results are noticed in the tin cans and in the pint andquart glass jars. A shortertime is required to reach thetemperature of the retort at121° than at
. A study of the factors affecting temperature changes in the container during the canning of fruits and vegetables . 100°, 109°, 116°, and 121° C. These curves were plotted from read- ^aac atintervals of 5 minutes. Rise in temperature when processed : A, A ^00° C. ; B, at109° C. ; C, at 116° C. ; D, at 121° C. at 116° about 1 hour and 10 minutes, and at 121° it requires 1 hourto reach the processing temperature in a No. 2 tin can. Similar results are noticed in the tin cans and in the pint andquart glass jars. A shortertime is required to reach thetemperature of the retort at121° than at any lower proc-essing temperature. Withmany vegetables and fruitsthere is a slowing down inthe rate of rise as the tem-perature goes higher, owingto the going into solution ofstarch, protein, or other ma-terial, which changes the vis-cosity of the material. Thischange in viscosity interfereswith convection, and so theprocess is slowed down. Achange of exactly the oppo-site character is taking placein the tomato. The tomatofruit is very succulent, andits tissues are easily broken down at high tempera-. te *?0 SO 60 70 80 SOT/Af£ //V M/NUTES Fig. 47.—Time-temperature relations for to-matoes when processed in pint glass jarsat 100°, 109°, 116°, and 121° C. These curveswere plotted from readings made at intervalsof o minutes. Rise in temperature whenprocessed: A, At 100° C.; B, at 109° C.;C, at 116° C.; D, at 121° C. TEMPERATURE CHANGES IN CANNING FRUITS AND VEGETABLES. 41 tures. There is very little starch, pectin, or other readily solublecolloidal material in the tomato. It consists of organic acidsand sugars, with insoluble cell tissues and a large amount of a high temperature is reached the tissues begin to collapse, leav-ing a free liquid in which convection can take place. This explainsthe greater rate of temperature change at the higher processingtemperature than at the lower. Such high temperatures as 109°, 116°, and 121° C. are not neces-
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectcanning, bookyear1921
