Aug. i6. 1920 Ripening and Storage of Bartlett Pears 489 



RELATION OF SUCROSE) TO REDUCING SUGAR DURING STORAGE 



There is a marked increase in sucrose during the time between picking 

 and the full ripening of the same fruit. This is shown by a comparison 

 of the distance between curves i and 2, representing the sucrose in the 

 fruit fresh from the tree, and between curves 3 and 4, showing the 

 sucrose in the same fruit when ripe. There is a very marked increase 

 in sucrose during storage in the earlier pickings, and this increase is 

 even more marked in the late pickings. The late pickings show very 

 little increase in reducing sugar between the time of picking and the 

 time the fruit was ripened, while the increase in sucrose was very marked, 

 being sufficient to make the total sugar increase between the time of 

 picking and full ripeness practically as much in late-picked as in early 

 picked fruit. There seems to be little relation between temperature and 

 kind of sugar in the fruit, the 70°, 40°, and 30° F. storage lots being 

 quite similar in the proportion of sucrose to reducing sugar. 



A review of all the curves indicates that, whereas in the early picked 

 fruit almost all of the sugar is in the form of reducing substances, the 

 increase in reducing sugars in successive lots, as the season progresses, 

 is much less marked than is the increase of sucrose. In all the lots, 

 reducing sugar in the late picks seemed to run to between 7 and 8 per 

 cent of the green weight of the fruit, after which there was very little 

 increase in reducing substances, while sucrose continued to increase 

 rapidly until after the last pickings were made. 



RELATION OF ACIDITY TO TIME OF PICKING 



In the relation of acidity to the time of picking there is not so distinct 

 a correlation in all cases as there is for the sugars. Fruit from different 

 districts seemed to respond somewhat differently in this regard, though 

 certain general tendencies hold for all regions. Figures 5 to 8 summarize 

 the results on acidity, computed as malic acid in terms of percentage 

 of wet weight of the fruit. Curve i in each plot represents acid in the 

 green fruit, curve 2 in fruit ripened at 70° F., curvx 3 in fruit ripened 

 at 40°, and curve 4 in fruit ripened at 30°. 



In fruit from Suisun, Calif., (fig. 6) there is a constant decrease in 

 acid in the green fruit from the time of the first picking until the last. 

 On the other hand, in fruit from Sacramento (fig. 5) there is a slight 

 rise until July 5, about the opening of the picking season, followed by 

 a drop toward the end of the season. In fruit from the more northern 

 sections, however, there is an increase in acid instead of a decrease. 

 The increase is rather slight in the Medford pears (fig. 7), but very 

 marked in those from Yakima (fig. 8). It is interesting to note that, 

 whereas the acidity of the fruit decreased in the California sections, 

 fruit from the Medford section showed a slight increase, and that from 

 the still more northern Yakima section showed a very marked increase 

 183719°— 20 2 



