208 MISC. PUBLICATION 5 4 0, U. S. DEPT. OF AGRICULTURE 



SWEETPOTATOES 



Sweetpotatoes rank next to potatoes in importance as material for 

 dehydration, and are an important crop in the South and in the Middle 

 Atlantic States. Approximately 707,000 acres of sweetpotatoes were 

 harvested in 1942. Georgia, with 100,000 acres, or 14 percent of the 

 total, ranked first in acreage harvested, as well as in total production. 

 The 1942 production of 1.8 million tons was only one-sixth as much 

 as the potato production in that year. In the years 1930-39 the com- 

 bined production of nine Southern States, which outranked all other 

 States, averaged 1.6 million tons or 80 percent of the total. The har- 

 vesting of this crop extends from as early as June to August in 

 Georgia, and from as late as September to November in many of the 

 other sweetpotato-growing States. The average yield per acre for 

 all States was 2.5 tons in 1942. 



Both the moist "yarn" and the so-called dry-flesh varieties are 

 suitable for drying. The products, however, are different, and the 

 two types should not be mixed. Numerous varieties are grown, but 

 those that are of commercial importance are less than a dozen in 

 number, and of these not more than four or five are of importance. 

 Porto Rico and ^Nancy Hall are the chief varieties in the South. In 

 New Jersey, Maryland, Missouri, and Kansas, members of the Jersey 

 group — Big-Stem Jersey, Maryland Golden, Yellow Jersey, Orange 

 Little Stem, and Vineland Bush — are of chief importance. These 

 are not all equal in suitability for dehydration, and because of varietal 

 differences, as well as differences in soil and climatic conditions, tests 

 should be made prior to the establishment of a plant in a given area, 

 to determine (1) the operating conditions that make the best dried 

 product, (2) the acceptability of the product, and (3) the yield of 

 dried product obtainable from the material. 



Rather extensive trials have shown that Nancy Hall and Nancy 

 Gold yield dried products of the highest quality. Porto Rico, Orange 

 Little" Stem, Maryland Golden, Big-Stem Jersey, and Yellow Jersey 

 all gave equallv good dried products very close in quality to Nancy 

 Hall and Nancy Gold. 



Sweetpotatoes require special handling to prevent loss during stor- 

 age. Only well-matured stock should be used, and it should be cured 

 for 10 to 14 days at temperatures of 80° to 85° F. with a relative humid- 

 ity of 85 to 90 percent. This may necessitate the use of artificial 

 heat. After curing, the temperature is allowed to drop to about 55° 

 with a relative humidity of 75 to 80 percent. Short periods at tem- 

 peratures of less than 50° will do no harm, but exposure to low 

 temperatures for long periods may cause certain types of decay, fre- 

 quently characterized by the formation of dark spots which may show 

 in the raw material or develop only during the drying process. Pro- 

 longed storage of sweetpotatoes causes deterioration of the raw stock, 

 with resulting poor quality of the finished product when dehydrated. 

 Slatted crates, bushel baskets, or shallow bins are used for storage. 

 The roots should be handled as little as possible while stored, 



Sweetpotatoes are first washed and then steamed for 10 minutes to 

 facilitate peeling. Following washing, grading to size should be 

 performed if abrasion peeling is used, since grading results in con- 

 siderably reduced waste. Abrasive peelers cause a heavy loss when 



