8 BULLETIN 1041, U. S. DEPAETMEXT OF AGEICLLTURE. 



(3) Placing the cooked potatoes at once into No. 3 sanitary tin cans, using a 

 wooden plunger to pack closely and firmly. 



(4) Placing cans thus filled in the cooker and steaming in flowing sreani for 

 15 minutes. 



(5) Crimping on the covers, thus tightly sealing. 



(6) Processing for 70 minutes at a steam pressure of 15 pounds and cooling 

 by placing cans in tiers on the floor of the laboratory. 



The varieties and strains used in tliese tests included the Florida, 

 Belmont, General Grant, White " Yam," Pierson, Miles, Early Caro- 

 lina, Yellow Strasburg, Early Red Carolina, Eed Brazil, Yellow 

 "Yam," Purple "Yam," Dooley, Triumph, Porto Rico, Mullihan, 

 Norton, Haiti, Gold Skin, Japanese " Yam," Ballinger's Pride, Big- 

 Stem Jersey, Catawba White, Catawba Yellow, Nancy Hall, Southern 

 Queen, and a number of unnamed strains. 



Upon opening the canned material for examination the product 

 from all the varieties was found to be quite firm. The so-called moist 

 types were somewhat softer than the dry mealy varieties, but these 

 differences were not very marked. As will be shown later, this was 

 in striking contrast to the findings upon potatoes canned after curing 

 and storage. On the basis of observations made at this time the Miles 

 appeared to be the best among the light-colored varieties, while the 

 Dooley, Nancy Hall, and Mullihan were best among those with deep- 

 yellow flesh. The Early Red Carolina was best among those inter- 

 mediate in color. 



The necessity of a full pack and a thorough exhaust was made evi- 

 dent by these tests. Cans which were slack filled and processed with 

 the others showed upon opening a marked oxidation of the exposed 

 surface and the material immediately underlying it. Those portions 

 from which the air was excluded remained bright, as did also that in 

 the cans properly filled and exhausted. Upon storage the contents of 

 those cans insufficiently exhausted became in most instances entirely 

 black, accompanied with ver}^ marked corrosion of the cans. 



Close comparison of the canning quality of the varieties could not 

 be made from this material, since the processing, which was found too 

 severe, had caramelized some of the sugar, causing a distinct brown- 

 ing in the normally light-fleshed varieties and imparting to all of 

 them a somewhat undesirable caramel flavor. Sweet potatoes packed 

 in glass jars and processed in boiling water for one hour on each of 

 three successive days gave a product far superior to that just de- 

 scribed. It was apparent, therefore, that the matter of the length and 

 temperature of processing would have to be more thoroughly investi- 

 gated before much progress could be made. 



In the intermittent test just mentioned it was observed that the dis- 

 coloration of the cooked potatoes when exposed to the air promptly 

 disappeared when they were packed in glass jars, partially sealed, 

 and processed in boiling water. Exposure to air. as when an imper- 



