42 CIRCULAR 2 78, U. S. DEPARTMENT OF AGRICULTURE 



those decayed and seriously bruised and cracked. Investigations in 

 Oklahoma (15) indicated that refrigerated storage at 50° F. after a 

 curing period is best for the early crop. Some evidence has been 

 obtained, however, that, if early potatoes are to be used for chipping 

 purposes, a storage temperature of 60° to 70° is better than one of 50°. 

 The relative humidity should be the same as that for the late crop. 

 If refrigeration is not available, an underground storage cellar or 

 cave is next best if the temperature can be held below 70° and a fairly 

 moist atmosphere maintained to avoid excessive shrinkage. (See also 

 49.) 



It almost goes without saying that under the conditions suggested 

 the storage period would never be so long as is possible with late-crop 

 potatoes. 



LATE CROP 

 (Temperature, 38° to 50° F. ; relative humidity, 85 to 90 percent) 



Potatoes are stored either in cold or common storage, but the greater 

 part of the crop that is stored is held in common storage ((20). Like 

 most other vegetables that can be held for relatively long periods in 

 common storage, potatoes can be successfully kept through the fall 

 and winter months only in those sections where a sufficiently cold 

 winter climate prevails. In either cold or common storage a temper- 

 ature of 40° F. is as low as table or seed stock need be kept during the 

 first few months after harvest. At temperatures below this, there is 

 a tendency for potatoes to become undesirably sweet. However, if 

 sweetening occurs, a few days' exposure to ordinary living-room tem- 

 perature will partly restore the natural flavor. Potatoes should always 

 be kept in the dark to prevent greening. At 40° potatoes will remain 

 dormant 5 to 8 months after harvest, depending on the variety. If it 

 is desired to keep them longer than this, as is often the case with seed 

 stock, the temperature may be lowered to 38°. at which they should 

 remain dormant indefinitely. A storage temperature as low as 32° is 

 not only unnecessary but detrimental. 



Investigations have indicated that potatoes stored at 50° to 60° F. 

 have better texture, color, and flavor when cooked or made into chips 

 than the same stock stored at lower temperatures (64, 120), although 

 the higher temperatures are not suitable for long-time storage. When 

 potatoes are stored at these higher temperatures, sprouting will occur 

 more quickly. A limited amount of sprouting does not injure potatoes 

 for food purposes, but it makes the stock difficult to market because 

 usually only dormant potatoes are wanted. If sprouting has started it 

 can be checked by lowering the storage temperature. 



Potatoes that have been kept at 40° F. for a long time are seldom 

 suitable for processing, such as chip making, french frying, or dehy- 

 drating, without first being conditioned to reduce the quantity of sugar 

 that has accumulated. This is accomplished by holding the potatoes at 

 70° to 80° until trial cooking tests show that they have recovered suffi- 

 ciently for use. The length of the conditioning period will depend on 

 the variety and the amount of sugar that has accumulated: usually, 

 however, this will be 1 to 3 weeks (123) . 



