COLD STORAGE FOR APPLES AND PEARS 13 



ing is not desirable, however, the only recommendation that can be 

 made is to limit the storage season as much as possible and keep the 

 fruit under refrigeration. 



Pears 



Pears have a slightly lower freezing point than apples and, not 

 being subject to such low-temperature diseases as soft scald and brown 

 core, can be stored at slightly lower temperatures, 29° to 31° being 

 recommended. 



As pears are rather susceptible to shriveling, it is important to 

 keep the relative humidity of the storage room above 85 percent, 

 preferably about 90 percent. 



Pears are more responsive to high temperature than most varieties 

 of apples, so that it is very important that heat be removed as rapidly 

 as possible immediately after harvesting. They have a high rate 

 of respiration, and the heat of respiration is an important consider- 

 ation in storage, especially during the cooling period. For suc- 

 cessful storage, therefore, the fruit at the center of packages must 

 be cooled approximately to the storage temperature within a period 

 of 48 hours before the packages are stacked in the permanent stor- 

 age piles. This is usually done by circulating air at temperatures 

 of 26° to 31° F. through widely spaced stacks of packages imme- 

 diately after they are packed. After this initial cooling, packages 

 should be stacked so as to provide air channels for the continuous 

 removal of the heat of respiration and for uniform refrigeration 

 throughout the piles. Stacking away from the walls and on strips or 

 floor racks is necessary to prevent the conduction of heat to the fruit. 



Pears may be held in cold storage and subsequently washed and 

 packed without serious injury or disfigurement, provided ripening 

 has progressed only slightly. The prevalence of scratches and other 

 friction marks often found on fruit thus held depends on the stage 

 of ripeness rather than being due to the influence of refrigeration. 

 Holding the fruit for 2 or 3 weeks prior to washing and packing is 

 safe if the fruit is kept at 30° to 31° F. from the time it is harvested. 



LOSS OF RIPENING CAPACITY 



Following prolonged storage, certain varieties of pears may seem 

 to be in excellent condition but when taken to high temperatures they 

 fail to ripen. Although the color of the fruit may become yellow 

 in the ripening temperatures, the flesh does not soften or become 

 juicy. Bosc, Cornice, and Flemish Beauty exhibit this characteristic 

 and do so earlier in the season when stored at 36° F. rather than at 

 30° to 31°. It is important that these varieties be stored at optimum 

 low temperatures and for periods not longer than the varietal storage 

 season. Following storage, ripening must proceed promptly at opti- 

 mum ripening temperatures. 



OPTIMUM RIPENING TEMPERATURES 



Commercial varieties of pears grown in the United States do not 

 ripen satisfactorily for eating while held at 29° to 31° F. Some vari- 

 eties gradually become softer at these temperatures, while others 



