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 w^ere 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 continuoiTsly in boiling water. 



(2) li 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 

 fOiLmci that the potato was bright and attractive in color, no caramel- 



78646—22 2 



