A STUDY OF SWEET POTATO VARIETIES. 5 
canned product it is extremely desirable to know something about 
them. Shiver (18), McDonnell (15), and Keitt (11, 12, 13) have 
shown that the sweet potato has a high starch content, with some- 
what variable quantities of cane sugar and dextrose. The analyses 
I of these writers show the content of starch to vary between about 
10 and 29 per cent in the freshly dug potatoes, the average being 
approximately 20 per cent. Considerable differences in this respect 
are noted in the varieties at the time of digging. Keitt (12, 13) 
has given special attention to the moisture content and to the pro- 
portions of the various carbohydrates in sweet potatoes when dug 
at different stages of maturity. He notes that in the small potatoes 
the moisture content is comparatively low, while the starch and 
sugar are high; then comes a period of rapid growth, during which 
the water increases and the starch and sugars decrease; and as the 
potatoes approach maturity the tendency is for the starch to in- 
crease and the total sugars and water to decrease. The relative 
proportions of cane sugar and dextrose are shown to vary greatly, 
dependent apparently upon meteorological conditions. The total 
sugars during the periods of the tests varied between about 2 and 
6 per cent. 
During the curing process and in storage physiological changes 
take place which transform part of the starch to sugars and inter- 
mediate products. These transformations have been followed care- 
fully by several investigators. Harrington (7) was the first in- 
vestigator, apparently, to note these changes. In a study of 16 
varieties, covering a period of a little more than four months, this 
worker found that the average water content decreased from 71.35 
to 63.5 per cent, the invert sugar increased from 3.17 to 4.63 per 
cent, and the total sugars increased from 6.27 to 12.31 per cent. 
Taking as the cane-sugar content the difference between the total 
sugars and the invert sugar, it is found that the cane sugar increased 
from 3.1 to 7.68 per cent during this period. Shiver (18) obtained 
similar results, but noted a slight increase in the moisture content 
during storage. He showed, however, that there may be either an 
increase or a decrease in the moisture content, depending upon the 
storage conditions. Hasselbring and Hawkins (8, 10) have studied 
the chemical changes taking place when sweet potatoes are stored 
at different temperatures. They find a very great decrease in the 
starch and dextrose and a very great increase in the cane sugar when 
the potatoes are stored at low temperatures. These authors (9) 
have also measured the respiration of sweet potatoes during storage 
and have found some loss in reducing sugars through this cause. 
Miyaki (17), in studies upon the nature of the sugars found in 
sweet potatoes, concluded that the reducing sugars consisted of both 
