MISCELLANEOUS 389 



toes. At harvest time none of the varieties bore a determinable amount 

 of reducing sugar except Bhss Triumph, and it bore only 0.7 mg per gram of 

 juice. When put into storage none of the varieties contained any reducing 

 sugar. After 59 days of storage at 5° C (41° F), all varieties had accumu- 

 lated more than 3.0 mg per gram of juice of reducing sugar. Even Chip- 

 pewa with 5.7 mg per gram contained almost twdce this amount, and many 

 of them bore several times this amount. Pride of Multnomah, the highest, 

 had nearly seven times the maximum allowable for good chips. After 68 

 days' storage at 7° C (45° F) many of the varieties bore less or httle more 

 than this maximum; and at 8.2° C (47° F) for 78 days' storage, few bore 

 this maxunum of reducing sugar. Bhss Triumph was the worst offender 

 with nearly twice the maximum. It is evident that varieties vary greatly 

 in the rate at which they accumulate reducing sugars at 5° C (41° F) and 

 even at the other two temperatures used and that those near the top of the 

 table belonging to the Rural group are least inclined to accumulate reduc- 

 ing sugars. It is also evident that the accumulation of reducing sugars falls 

 rapidly as the storage temperature rises from 5° to 8.2° C (41° to 47° F), 

 several varieties giving rather slow sugaring even at 7° C (45° F), and 

 that only a few varieties accumulate considerable reducing sugar at 8.2° C 

 (47° F). Storage temperature of 1° C (34° F) in contrast to 5° C (41° F) led 

 to still greater accumulation of reducing sugar .-^ 



Cane sugar. While the cane sugar content of potato tubers has no part 

 in giving bro^vn chips, it is of interest to note the cane sugar content of 

 tubers at harvest tune and the effect of storage temperatures upon its 

 accumulation, for it is an important nutrient for the growing plant and it 

 modifies the flavor of cooked potatoes. Table 40 shows these points. At 

 harvest time all 25 varieties contain measurable amounts of cane sugar, 

 unlike the situation with reducing sugar; also at the time of putting into 

 cold storage after a period of air-temperature storage, all varieties contain 

 measurable amounts of cane sugar. During air-temperature storage most 

 varieties fall in cane sugar content, but some rise. Storage at 5° C (41° F) 

 for 59 days causes a rise in cane sugar content of all varieties — a very 

 marked rise in some. Even storage at 7° C (45° F) for 68 days causes a 

 rise in cane sugar in all varieties, an even higher rise in some than was 

 caused by 5° C (41° F) for a shorter period. Storage at 8.2° C (47° F) for 

 78 days causes relatively little change in cane sugar content, a slight fall 

 in some, and a slight rise in others. As is the case with reducing sugars, 

 varieties differ greatly in their power to form cane sugar at low tempera- 

 ture, and this power falls greatly from 5° to 8.2° C (41° to 47° F) ; but for 

 some varieties there is a rise instead of a fall from 5° to 7° C (41° to 45° F). 



De-sugaring at High Storage Temperatures 



Reducing sugars. When potatoes have accumulated much reducing sugar 

 due to storage at low temperatures, they de-sugar more or less readily 

 according to variety when transferred to high-temperature storage, although 



