FREEZING INJURY OF FRUITS AND VEGETABLES 5 



at least the most exposed parts of the pack. The length of expo- 

 sure varied from 3 or 4 hours to several days. Details of the tests 

 are given in table 1. Brief descriptions of the symptoms of freez- 

 ing injury in the various commodities appear in the text. In many 

 instances statements about freezing injury in the particular com- 

 modity as observed on the market are also given. Information as 

 to the temperature of the produce at different positions in the 

 package was obtained by means of thermocouples and a potenti- 

 ometer. The thermocouples were thrust into the produce to a depth 

 of 1 or 2 inches ; hence they did not show the temperature at the 

 surface. Statements concerning the time of the first occurrence of 

 freezing of each commodity are usually based on evidence obtained 

 by visual and manual examinations. 



The wraps used for apples, grapefruit, lemons, and oranges 

 were of the kind commonly used for these fruits in commercial 

 operations. 



In these tests it was possible to determine within rather narrow 

 limits the time when freezing occurred in a given commodity, espe- 

 cially in the more exposed parts of the package. It should be 

 clearly understood, however, that the periods given in table 1, 

 columns 6 and 7, are to be accepted as only approximate if it is de- 

 sired to apply them in the handling of other packs and kinds of 

 packages of the same commodities under various commercial 

 conditions. 



Apples 



experimental observations 



Apples in two eastern boxes were held in an 18° F. room for 51 

 hours ; those in one box were individually wrapped and those in the 

 other were not wrapped. The boxes were not papered over the 

 outside, but both were lidded. (For rate of cooling of these two 

 lots see figure 1.) When the fruits were examined immediately 

 after removal from the freezing room, freezing was found to 

 extend to the center of both boxes. 



After a week at 31° F. it was found that the severest injury was 

 in the unwrapped lot. The apples in that lot showed numerous 

 water-soaked bruises, with browning underneath, extending deep 

 into the flesh, and the flesh was generally dry and mealy. The 

 bruises occurred where the apples had touched each other or the 

 box, although they were not under pressure from the lid. Some of 

 these bruises were similar to those that can be produced by jolting 

 apples under pressure ; others extended so deep and the flesh was 

 so much browned that the injury could have been caused only by 

 freezing. A few fruits in this box were brown throughout, mushy, 

 and clearly frozen to death. The same symptoms, to a much 

 smaller degree, occurred in the wrapped apples, except that none 

 were brown throughout, watery, or mushy. 



Apples in two unpapered eastern boxes were held in a 21° to 24° 

 F. room for 54 hours. Those in one box were individually wrapped 

 and those in the other were not wrapped. On removal from the 

 freezing room, fruits were found frozen in all parts of both boxes 

 but not all fruits were frozen. When the fruits were cut, bruising 



