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in the second test. The remaining boxes cooled slightly slower than the pallet 

 loads of standard apple boxes. 



In both tests all types of boxes approached the air temperature closer 

 than one degree F. This is considered satisfactory performance. In general, 

 the approach temperature is very similar to that encountered with pallet loads 

 of standard apple boxes. 



Pallet Box Construction Recommendations 



Although there are some types of boxes in the test that require 3 times 

 as long to cool as others, the half-cooling time of the slowest is not prohib- 

 itive of use. Previous studies made by the Department of cooling rates of 

 apples wrapped and packed in standard boxes have showed the half-cooling time 

 for these boxes on pallets to range from 45 to 66 hours. In these same tests 

 packed apples stacked in individual rows with air circulation space between 

 each row required a half-cooling time of from 27 to 50 hours. From these 

 figures, it appears that the poorest cooling in pallet boxes is generally 

 faster than all but the very best performance of standard pack from "hot" 

 fruit as it comes from the field and then is placed in cold storage. 



While it appears from the present cooling studies that all of the pallet 

 boxes tested could be recommended as giving results as good as a standard pack 

 of "hot" fruit, it must be remembered that investment in equipment for refrig- 

 erating a plant is expensive. Every possible means should be devised for 

 using the refrigeration machinery as efficiently as possible. It is only 

 logical to select and use those features of pallet box construction that give 

 greatest economy of refrigeration equipment. Some pallet boxes will use less 

 refrigeration than others because the faster cooling rapidly reduces the heat 

 of respiration given off by the fruit so that less total heat is generated and 

 less total heat needs to be removed. 



These tests indicate that a pallet box constructed with either sides or 

 bottoms having approximately 8 to 11 percent free area will provide excellent 

 cooling characteristics. A box constructed with this much free area in both 

 sides and bottom will have substantially better cooling characteristics than 

 the present standard container. When the apple industry adopted palletization, 

 it accepted some penalty in cooling performance. Unpacked apples in standard 

 boxes stacked in individual rows enjoy a half-cooling time about 50 percent 

 of that required when placed in pallet loads. It is possible that proper 

 pallet box design offers an opportunity to regain some of the cooling performance 

 that was lost when palletized handling was adopted. 



The test indicates that side ventilation may be as effective as bottom. 

 Yet, this conclusion is subject to some qualification. The pallet box with 

 spaced sides and solid bottom, and the box with solid sides and spaced bottom, 

 representative of these two situations, differ somewhat in dimensions and 

 percent of free area, and the difference in both cases favors the box which 

 has the side ventilation. However, the performance of the box with side 



