HANDLING APPLES FROM TREE TO TABLE 



11 



of these containers, however, included liners and pads, as well as oiled 

 wraps or shredded oiled paper. The eastern crate contained 20 percent 

 more apples and was the tighter package; after 10 days the fruit in its 

 center had cooled only 22°, while that in the standard box had cooled 

 34°. 



The results of the tests should not be interpreted to mean that use of 

 pads, liners, and other packing material is undesirable, but rather that 

 these materials insulate the fruit and increase the requirement for re- 

 frigeration if properly packed apples are to be cooled as quickly as is 

 desirable. 



In precooling apples, air at a temperature below 32° F. is used to 

 rapidly lower the temperature of the fruit. The greater the difference 

 between the temperature of the apples and that of the air, and the more 

 rapid the rate of air movement, the more rapid the rate of cooling will be. 

 However, as the temperature of the fruit approaches that of the cooling 

 medium the rate drops (fig. 4). 



60 72 84 96 108 



ELAPSED TIME (HOURS) 



168 



Figure 4. — Rates of cooling of apples packed in bushel baskets and stored at 32° F. 

 in still and in moving air. Velocity of the moving air was approximately 200 feet 

 per minute. The thermometer was placed in centermost fruit in each container. 



Some persons believe that when apples are cooled too rapidly the 

 quick change in temperature may produce shock to the fruit, with con- 

 sequent ill effects. Only varieties that are susceptible to soft scald are 

 likely to be injured by fast cooling in storage. With other varieties 

 the more rapidly fruit can be cooled to the proper storage temperature, 

 the more quickly will deteriorating processes of ripening be arrested 

 and the longer the fruit can be kept in good condition. 



While apples are not commercially precooled to the same extent 

 as are peaches, pears, plums, and certain other fruits, in many cases it 

 would undoubtedly be beneficial to precool them, Delicious in particular 

 because this variety is so prone to become mealy and overripe. Records 

 of fruit temperatures, if taken in many storages, would disclose that 

 most of the fruit is not cooled to 32° for several weeks after harvest. Mean- 

 while, the rate of ripening is being arrested only in proportion to the rate 

 of cooling. The slow cooling is often due to lack of sufficient refrigerating 

 capacity of the cold-storage plant, but it may also be due to faulty stow- 

 age in the room, particularly failure to leave space for air circulation 

 through the stacks and to spread out large receipts of warm fruit. 



Records taken in packages held at 32° F. and stowed as they would 

 be in commercial practice showed that the rate of cooling was faster in 

 the top layers of the stacks because the air could circulate more freely 

 there. The apples cooled more in the first 12 hours than in the next 12 

 and the rate of cooling fell off progressively thereafter as the temperature 



