Reducing Sugar 



As shown in figure 4, reducing sugar in the six varieties of mature 

 apples ranged from approximately 34 to 50 percent of the total solids 

 before storage and from 41 to 58 percent after 7 months of storage. 

 Delicious apples were highest in reducing sugar at all times. Stayman 

 apples were lowest in reducing sugar before storage and after 3 months, 

 whereas after 5 and 7 months Rome Beauty and Winesap apples 

 were nearly like Stayman in reducing-sugar content (range of 43 to 

 49 percent). Immature apples had 34 to 55 percent reducing sugar 

 with the same varieties outstandingly low or high. 



REDUCING SUGARS 



Percent of Total Solids 



32°F* 



50 



- 40 



30 - 



40°F* 



Delicious 

 ^— ^— Golden Delicious 

 -• — • — »- Jonathan 

 ••••••• Rome Beauty 



^"•X^~ Stayman 

 »«•.—.» Winesap 



MONTHS 



*STORAQE % TESTED IN FIRST YEAR ONLY 



U.S. DEPARTMENT OF AGRICULTURE 



NEG. 5579-58(10) AGRICULTURAL RESEARCH SERVICE 



Figure 4. — Reducing-sugar content of six varieties of mature apples before and 

 after storage at 32° and 40° F., mean values for 2 crop years combined. 



In nearly all tests, the six varieties of mature apples showed in- 

 creases in reducing sugar with each increment of storage time. Snyder 

 (4-0 reported that invert sugar results from the conversion of starch 

 and sucrose in apples and thus apples become sweeter during storage. 

 Vecher and Bukin (49), who are in agreement with his findings, 

 found that other compounds such as pectins and hemicelluloses were 

 also responsible for the increase in invert sugar. 



Although all varieties appeared to increase in reducing sugar more 

 rapidly at 40° F. than at the lower temperature, differences related 

 to storage temperature were significant only in the second year for 

 both mature and immature apples. 



The coefficient of correlation between values for reducing sugar 

 and total acidity was —0.62 and between reducing sugar and pH, 

 + 0.70. Both were highly significant; in other words, 38 percent of 

 the variation in total acidity and 49 percent of the variation in pH, 

 respectively, were associated with the reducing-sugar content of 

 apples in this study. 



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