A STUDY OF SWEET POTATO VARIETIES. 



19 



suiRcient to alter the plasticity to any marked extent. The Southern 

 Queen changed less rapidly than any of the others during curing, 

 but lost its firmness rapidly in storage, arriving at the end of the 

 test period in a very soft condition. Very marked changes took place 

 in the Nancy Hall and the Porto Eico during the curing period. 

 At the end of this time both were very soft. A continuous loss in 

 the case of the Nancy Hall and a slight increase in the Porto Rico 

 are noted, but they have no practical significance probably, as both 

 varieties had become very soft. 



All the different potatoes studied have been found to vary in some- 

 "what the same way, as is shown in the examples just given. Though, 

 as has been pointed out, some variations have been noted in the con- 

 sistency at the time of digging, all when freshly dug yield a com- 

 paratiA^ely firm product. Table 3 shows the results of consistency 

 tests upon these varieties made after curing and storage. The tests 

 were carried out in the same manner as in the tests just described. 

 The varieties are arranged in the order of their firmness as found 

 in these tests. 



'Table 3. — Relative plasticiti/ of different varieties of sioeet potatoes canned in 

 the form of pie stock after curing and storage. 



Variety. 



Grams. 



Variety. 



Grams. 



Variety. 



Grams. 



Early Red Carolina 



No. 11286 



210 



172 



158 



137 



125 



108 



105 



105 



97 



95 



89 



85 



82 



81 



78 



No. 11284 



75 

 71 

 68 

 64 

 62 

 60 

 60 

 58 

 52 

 50 

 50 



No. 39833 



42 



Triumph 



Key West 



35 





No. 10650 





34 









34 



No. 7980 



Florida 



Southern Queen 



30 



Yellow Jersey .... 



Early GaroUna 



Ballinger 's Pride 



30 







29 



Improved Big Stem 





White"Yam" 



29 



Red Brazil 



Creola 



28 



No. 10412 







28 



Dahomey . 



Catawba White 



1 Vineless Pumpkin 

 "Yam" 







Yellow Belmont 



No. 11285 



46 



25 



Gold Sldn 



45 

 45 

 45 



Nancy Hall 



20 



Haiti .. 



Vineless 







No. 49711 



No. 22437 











It will be seen that after curing and storage the plasticity varies 

 all the way from quite firm to very soft, all degrees of plasticity being 

 found. 



These observed changes in consistency during curing and storage at 

 once raised the question as to the cause, and the samples were sub- 

 mitted to chemical analysis to determine what substances were in- 

 volved. The analyses were carried out in the following way : Dupli- 

 cate samples of 100 grams were weighed out from the thoroughly 

 mixed material and enough 95 per cent alcohol added to give an 80 

 per cent mixture. This was thoroughly stirred, and after standing 

 for several hours the alcohol was decanted through an extraction cup 

 into a flask and more 95 per cent alcohol added to the material. This 

 was repeated three or four times. After decanting for the last time 



