498 Journal of Agricultural Research voi. xix. no. 10 



to hold the fruit for only a few weeks, somewhat higher temperatures 

 are permissible; but even for short storage periods a low temperature, 

 followed by the removal of the fruit and ripening at outside air tempera- 

 ture, gives a better product. 



(6) The cooling capacity of the storage plant should not be overtaxed. 

 It is possible in the case of Bartlett pears to "store on the tree" to a very 

 marked extent. Two weeks' time on the tree makes only a small differ- 

 ence in the length of time pears will remain sound after removing from 

 the tree, so for cannery trade it is not necessary to pick the entire crop 

 within a very short time. Of course, other factors, such as amount of 

 drop, load on the trees, etc., must be considered. 



The foregoing suggestions presuppose a very close working agreement 

 between producer, canner, and cold storage; and this is essential for 

 successful handling of Bartlett pears through cold storage. The fruit 

 must be sent to the storage plant quickly if it is to be held in storage, and 

 the cooling capacity must be such that the fruit can be cooled down 

 within a short time. The temperature and storage recommendations 

 apply only to Bartlett pears, since other varieties have been found to 

 give different responses under storage treatment (8, 9). 



For the dehydration of Bartlett pears, if a drying plant is used, the 

 same principles apply as for canning. On the other hand, if sun drying 

 is used, the problem is much simplified, as the fruit can be handled in 

 almost any quantity within a short time. For drying, however, it is 

 of twofold importance that the fruit remain on the trees as long as 

 possible, for the quality is not only improved but the accumulation of 

 sugars gives an increase in the weight of dried product per pound of 



green fruit. 



SUMMARY 



There is a marked and quite uniform increase in total sugar in Bartlett 

 pears from early summer until after the time of the close of the commer- 

 cial picking season. The increase during the latter part of the season is 

 mainly due to an accumulation of sucrose, while the earlier increase is 

 due mainly to reducing sugar. 



A distinct relationship was found between the total amount of sugar 

 present in the ripe fruit and the temperature of the storage at which it 

 had been held from the time of removing from the tree until ripe. Pears 

 ripened at 70° F. contained the highest percentage of sugar, those ripened 

 at 40° possessed the lowest total sugar content, and those held at 30° for 

 from 6 to 14 weeks and then ripened at room temperature were inter- 

 mediate in amount of total sugar. There was no marked relation between 

 temperature of storage and relative amount of sucrose and reducing 

 sugar. 



Percentage of titratabie acid in the fruit tended to decrease in fruit 

 from the California sections as the season advanced, while it tended to 



