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UNITED STATES DEPARTMENT OF 



RECEIVED 



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DEPARTMENT BULLETIN No. 1133 



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Washington, D. C. 



Issued February 28, 1923 

 Revised May, 1929 



THE FREEZING TEMPERATURES OF SOME FRUITS, 

 VEGETABLES, AND CUT FLOWERS 



By R. C. Wright, Physiologist, and George F. Taylor, formerly Biophysicist, 

 Office of Horticultural Crops and Diseases, Bureau of Plant Industry 



INTRODUCTION 



There is an ever-increasing demand from persons interested in the 

 growing, shipping, and handling of produce for exact data on the 

 freezing points, or the temperatures at which various products freeze. 



The extent of damage due to the freezing of produce in transit 

 naturally varies from year to year, but it is usually very heavy, 

 aggregating frequently several hundreds of thousands of dollars 

 during a year. This in general applies not only to such products as 

 apples and potatoes, most of which are grown in the North and har- 

 vested and shipped in the late fall and winter, but to products which 

 are grown in the South and Southwest during the winter and shipped 

 to the northern markets. This latter group includes citrus fruits, 

 strawberries, tomatoes, lettuce, string beans, cabbage, cauliflower, 

 eggplant, etc. Cars of these food products often leave the shipping 

 point under refrigeration and in 24 to 36 hours may pass into a zone 

 of freezing temperatures. As they approach the more northern 

 markets they may be exposed to temperatures ranging several degrees 

 below their freezing point. Under certain conditions when harvested 

 in warm weather some of these products are precooled — that is, rapidly 

 cooled to a refrigerating temperature, either immediately before or 

 directly after they are placed in the car for shipment, in order to delay 

 maturity and consequent deterioration. Where precooling is practiced, 

 it is, of course, essential to know the temperatures to which the prod- 

 uct can be lowered with absolute safety. 



It is of great importance to the commercial cold-storage man to 

 know the exact freezing points of fruits and vegetables that he 

 handles. In most cases fruits and vegetables other than dried or 

 prepared products when placed in cold storage are alive, and the 

 problem is to keep them alive and healthy throughout their storage 

 period. Since various fruits and vegetables freeze at different 

 temperatures, there is more or less doubt in the minds of those inter- 

 ested as to the proper and safe temperatures at which to hold these 

 various products in storage. One of the problems in the storage of 

 many of these products is to hold them at a temperature low enough to 

 slow down the living processes in order to prolong their storage life 



41676°— 29 



