258 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



When a month or so has elapsed after the freezing, the segments 

 of fruit begin to pull apart because of the drying of the frozen tissue 

 (figs. 3 and 4). This condition is best seen in cross-section. It shows 

 first in fruit which was exposed to the morning sun where it may 

 appear within ten days after the freezing. Sometimes, especially with 

 fruit inside the tree, this breaking down may not begin for three 

 months. 



How to Determine the Extent of Fruit Injury. It is frequently 

 of importance soon after a freeze to be able to determine the extent 

 of the fruit injury. The external and internal character shown by 

 frozen fruit are given in the preceding sections. 



Another method of recognizing fairly quickly the good from the 

 frozen fruit was found in the changes in specific gravity that took 

 place in fruits that were picked and stored. Good fruit increases in 

 specific gravity by the drying out of the skin causing a decrease in 

 volume without much loss of the interior juices. Frozen fruit, how- 

 ever, rapidly decreases in specific gravity as the interior juices pass 

 out into the skin readily, and are evaporated without producing much 

 change in volume. 



In an investigation conducted by Professor John S. Burd and Mr. 

 W. H. Dore of the College of Agriculture it was found that these 

 changes could be greatly hastened by picking and storing the fruit 

 in a warm atmosphere. The following statements prepared by them 

 will show the possibilities of this method. 



The following typical data illustrate the relative changes in specific gravity 

 of unfrozen and frozen fruit over several time intervals when stored in a cool 

 room. The figures in every case represent the average of a number of individuals. 



FRUIT STORED IN COOL BOOM 



After After After 



Initial 4 days 8 days 16 days 



Unfrozen oranges 0.857 0.865 0.876 0.894 Maximum 50 days 0.951 



Frozen oranges 0.838 0.836 0.828 0.787 After 40 days 0.689 



Unfrozen lemons 0.942 0.955 0.967 0.981 Maximum 50 days 1.023 



Frozen lemons 0.806 0.747 0.615 



When sound and frozen fruit are stored in a room at a temperature of 95 F., 

 the specific gravity changes are similar in character to those observed in the cold 

 room fruit, but the rate of change is about three times as great in the warm room 

 as in the cold, as shown in the following data. 



DIVISION OF SUBTROPICAL HORTICULTURE 



COLLEGE OF AGRICULTURE 



BERKELEY, CALIFORNIA 



