VEGETABLE AND FRUIT DEHYDRATION 199 



spinach.) The weight of material lost through trimming and sort- 

 ing is less than for other greens and is usually about 30 to 40 percent. 

 Information on blanching and dehydration is contained in tables 21 

 to 25. Dried mustard greens can be rehydrated and tested for qual- 

 ity by the method used for other greens. 



ONIONS 



The leading onion-producing area is in New York, where the 1912 

 commercial production was 163,000 tons. The national average yield 

 per acre in 1942 was 7 tons, and the yield was several tons higher in 

 areas of heavy commercial production. During the early stages of 

 growth the temperature should be fairly cool and the moisture supply 

 ample. In the early-producing States, the onion harvest begins in 

 April and ends in June. The intermediate States harvest this crop 

 during the summer months, and the late States— eastern, central, and 

 western — from August to October. The marketing period for late 

 onions lasts 6 or more months after the final harvest, and extends to 

 the late spring of the following year. 



In New York the most popular varieties of onions are Early Yellow 

 Globe and Ebe-nezer : in Colorado, Mountain Danvers ; in Texas, Yellow 

 Bermuda. The most common fault found with dehydrated onions is 

 their lack of pungency. The Ebenezer, Barnett, Southport Yellow 

 Globe, White Portiigah Red Creole, White Creole, and Yellow Danvers 

 Flat are very strong onions and make excellent dried products. The 

 White Portugal makes an excellent dried product, but the yield of 

 onions per acre is low. Sweet Spanish, the various Bermudas, and 

 similar types of onions are too mild for dehydration. Some of the 

 more pungent varieties, for example Australian Brown (Oregon 

 Brown or Buckskin), may yield a bitter-flavored dried product under 

 certain drying conditions, but under other conditions they make good 

 products. Australian Brown has a high percentage of dry matter, 

 is an excellent keeper, and could be used to extend the season of opera- 

 tion, but it is difficult to peel. There is considerable variation in per- 

 centage of dry matter among varieties of onions ; in this respect the 

 mild varieties are low, and the pungent varieties high. 



In the northern States, onions are held in common storage during 

 the winter months. Part of the crop in this section is cold-stored, 

 because after March there is likelihood of sprouting. The Ebenezer, 

 Australian Brown, Creole and various Globe varieties are the best 

 keepers. The most important requirement in storage is controlled 

 relative humidity, ranging from 70 to 75 percent. Higher humidities 

 may cause root groAvth and decay in the form of neck rot. A tem- 

 perature of 32° F. is sufficiently low to keep onions dormant and 

 reasonably free from decay, provided they are in sound condition and 

 well cured when stored. Good ventilation should be provided. If 

 the onions are packed in sacks, they should be set off the floor 2 to 4 

 inches with space provided around each sack. Sacks are usually 

 stacked in pairs laid crosswise, five or six sacks high, and sometimes 

 placed on a framework of shelves to provide ample ventilation. In 

 some districts onions are stored in slatted crates. Good storage stock 

 can be kept 6 to 8 months. 



