A STUDY OF SWEET POTATO VARIETIES. 9 
feet seal allowed the air to enter the jar during cooling, resulted in a 
reappearance of the discoloration; whereas in jars in which the seal 
was perfect the material remained bright for an indefinite period. 
It was therefore apparent that peeling while raw had no advantage, 
and in all subsequent experiments the potatoes were cooked in the 
skin and peeled afterwards. 
In order to determine the processing temperature and time periods 
which would yield the desired quality from the standpoint of appear- 
ance and flavor, the following experiments were carried out. 
Potatoes of the three varieties, Nancy Hall, Big-Stem Jersey, and 
Southern Queen, were washed, placed on trays in a steam chamber, 
and subjected to flowing steam for 30 minutes. At the end of this 
time they were removed from the chamber, rapidly peeled by hand, 
and then passed through a food chopper. This gave uniform material 
for the tests. One lot of No. 2 and No. 3 cans of each variety was 
sealed at temperatures ranging from 70° to 80° C, and then another 
lot was allowed to cool to room temperature and then processed. 
From each of these lots a series of cans was treated as follows : 
(1) 1, 2, 3, 4, 5, and 6 hours continuously in boiling water. 
(2) 11 hours in boiling water on each of three successive days. 
(3) 30, 45, 60, 75, 90, and 120 minutes in the steam retort at 109° C. (steam 
pressure about 5 pounds). 
(4) 30, 45, 60, 75, 90, and 120 minutes at 116° C. (steam pressure about 10 
pounds). 
(5) ' 30, 45, 60, 75, 90, and 120 minutes at 121° C. (steam pressure about 15 
pounds ) . 
Examination of the contents of these cans showed that for the 
present needs the most satisfactory results could be obtained under 
the conditions described with No. 2 cans processed at 116° C. for 45 
minutes and with No. 3 cans treated similarly for one hour. Satis- 
factory results as to quality were likewise obtained both by the inter- 
mittent processing in boiling water for 1^ hours and by continuous 
boiling in the water bath for three to four hours. 
The supply of many of the varieties available for this work hav- 
ing been exhausted, it was impossible during this first season to 
carry out complete comparative tests based upon the data thus far 
obtained. Such material as did remain, however, was canned, and 
comparisons were made with that handled earlier in the season. The 
method of preparation of this material was essentially as described 
under the last experiment, special care being taken that the cans 
were properly filled with the hot material and sealed at once. No. 2 
cans were employed and processing was done in the steam retort at 
10 pounds' steam pressure for 45 minutes. 
On opening these cans for the examination of the contents it was 
found that the potato was bright and attractive in color, no caramel- 
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