COMMERCIAL STORAGE OF FRUITS AND VEGETABLES 15 



Deglet Noor, the most important variety grown in this country, is 

 of the cane-sugar type. Dates of this variety, cured grade, keep well 

 until March at 28° to 32° F. and for a year at 24° to 26° or lower, 

 whereas the noncured grade requires 18° or lower for storage until 

 March, and 0° to 10° for a year. In Deglet Noor dates that have 

 become overripe or have been held under unfavorable storage condi- 

 tions the cane-sugar is inverted and the dates become soft, sirupy, and 

 darker in color. Such dates are commonly graded as "dark soft." If 

 properly cured they can be stored at 28° to 32° until Christmas with- 

 out becoming objectionably dark and sirupy, although a temperature 

 of 0° to 10° will be needed if they are to be stored until March. If 

 such dates are not cured a temperature of 0° to 10° is necessary for 

 even short- time storage (41). 



Halawy (Halawi), Khadrawy (Khadrawi), Zahidi, and Saidy dates 

 are all of the invert-sugar type, and the cured grades can be kept until 

 Christmas at 28° to 32° F. without forming sugar spots but require a 

 temperature of 18° or lower if stored until March. Noncured grades 

 of these varieties require 0° to 10° for even short storage. After 

 Christmas it is well to shift all dates of invert-sugar type remaining 

 in storage to "freezers" of 0° to 10° F. {2, 38). 



DEWBERRIES 



Short storage only. See Raspberries. 



GRAPEFRUIT 



(Relative humidity, 85 to 90 percent) 



Storage rooms for grapefruit should have a relative humidity of 85 

 to 90 percent. Lower humidities are favorable to pitting, and higher 

 ones may increase decay. 



For short-time storage, grapefruit can be held satisfactorily at a 

 temperature of 32° F. For longer periods the temperature to be used 

 will depend on the character of the fruit and the troubles most likely 

 to be encountered. For fruit grown in sections where stem-end rot 

 is prevalent, this disease is likely to be the determining factor; it will 

 generally be advisable to use a comparatively low temperature range 

 (32° to 34°). On the other hand if the fruit is grown in regions where 

 stem-end rot is not prevalent, the limiting factors are likely to be 

 storage pitting and watery break-down, which develop most seriously 

 at temperatures of 40° or lower. For such fruit a temperature of 45° 

 to 55° is satisfactory. The more rapid development of undesirable 

 high color and the increase in blue mold and green mold decay at the 

 higher temperatures have not been found as objectionable as the 

 pitting that results from storage at lower temperatures. 



Sound fruit that is not overmature nor likely to suffer from stem-end 

 rot can usually be held for 6 weeks without serious spoilage at the 

 higher temperature ranges mentioned above, and this storage period 

 can sometimes be doubled with satisfactory results. Weak or over- 

 mature fruit requires close watching from the time it is removed from 

 the tree, regardless of storage conditions. 



The percentage of stem-end rot in Florida and Texas grapefruit will 

 be greatly reduced if the fruit is properly treated with borax or sodium 

 metaborate, and pulled from the tree instead of being clipped. The 

 disbuttoning that frequently results from the ethylene treatment 

 is also effective in reducing loss from stem-end rot. As compared 



