UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 956 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



August 17, 1921 



A STUDY OF THE FACTORS AFFECTING TEMPER- 

 ATURE CHANGES IN THE CONTAINER DURING 

 THE CANNING OF FRUITS AND VEGETABLES. 1 



By G. A. JMagoon and C. W. Culpepper, Office of Horticultural and Pomological 



Investigations. 



CONTENTS. 



Page. 



Basis of the study 1 



.Review of the literature 2 



Methods and apparatus 6 



The steam retort 7 



The brass fitting 8 



Thermocouples 10 



The water bath . 10 



Preliminary experiments - 10 



Distilled water 10 



Brine 14 



Sugar solutions 14 



Starch solutions 16 



Single-period processing 17 



String beans 18 



Peas 21 



Lima beans 24 



Soy beans 25 



Asparagus 28 



Page. 

 Single-period processing — Contd. 



Sweet corn 29 



Pumpkin 34 



Sweet potatoes 30 



Tomatoes 39 



Cabbage . 41 



Factors affecting the change of 

 temperature at the center of 



the can 42 



Intermittent processing 45 



String beans 45 



Sweet corn „■ 47 



Soy beans 48 



Sweet potatoes 50 



Factors influencing the rate of 



change of temperature 50 



Summary 53 



Literature cited 55 



BASIS OF THE STUDY. 



Successful preservation of foods by canning is due primarily to 

 the fact that in the processing, or cooking, the bacteria and other 

 microorganisms which cause spoilage are destroyed. Since the 

 elimination of these microorganisms is dependent upon the use of 

 heat as a sterilizing agent, it becomes of paramount importance to 

 know just what temperatures and processing periods will destroy 

 them. If uniformly good results are to be expected, a sufficient de- 

 gree of heat must penetrate to all parts of the can or jar, and must 



1 The manuscript of this bulletin was submitted for publication on February 27, 1920; 

 circumstances of an incidental character interfered with its early issue. 



44900°— 21 1 



