12 BULLETIN 1041, U. S. DEPAKTMENT OF AGEICULTURE, 



their yields, canning qualities, and other characters. These descrip- 

 tions may be found of value in choosing the variety or varieties best 

 suited for any particular purpose. 



COMPARATIVE CANNING TESTS IN 1920. 



There remained to be determined the comparative qualities of the 

 different varieties when canned as whole potatoes, and certain of the 

 problems connected with the canning of sweet potatoes required 

 further investigation. Moreover, several additional varieties were 

 made available for use. It was decided, therefore, to continue the 

 studies for another season in order to make the work as complete as 

 possible. 



Forty-three varieties and strains were grown especially for this 

 purpose. They were dug on October 14 and 15 and the main portion 

 of each cured and stored, as in 1919. From the Porto Rico, Xancy 

 Hall, Big-Stem Jersey, and Southern Queen varieties a sample was 

 canned immediately ; another at the end of 10 days' curing, when it 

 was transferred to storage ; a third sample after 10 days in storage ; 

 and a final sample after 20 days in storage. This was done to deter- 

 mine just what effect curing and storage have upon the canning 

 qualities of different types of sweet potatoes. These results will be 

 considered under the heading of "Consistency" (see page 16). 



The main variety canning tests were made from November 26 to 

 December 6. The handling of the potatoes differed from that of 

 the 1919 season in that they were packed in two forms, as pie stock 

 and as whole potatoes. For packing whole the potatoes were washed, 

 the largest roots cut into smaller sizes to facilitate cooking, when 

 necessar}^ ; placed on trays in a steam chamber ; and cooked in steam 

 at 100° C. for 30 to 40 minutes, or until done. They were peeled 

 rapidly by hand while still very hot, a towel being used to protect 

 the hands, the hot potatoes packed into No. 3 sanitaiy cans, and 

 sealed immediatelj". The potatoes being very hot and the cans well 

 filled, no exhaust was found necessary. The cans thus prepared 

 were then processed at 116° C. for one hour, at the end of which 

 time the}' wei'e removed from the retort and cooled in air. The va- 

 rieties canned as pie stock were handled as during the 1919 season, 

 the material after passing through the food grinder going directly 

 into No. 2 sanitary cans, then sealed at once, and processed imme- 

 diateh' at 116° C. for 45 minutes. 



On December 10 these samples of canned sweet potatoes, both in 

 the form of pie stock and as whole potatoes, were submitted to a 

 committee of judges, as in 1919. This committee was made up of 

 representatives from the Research Laboratory of the National Can- 

 ners' Association and of the States Relations Service, the Office of 



