Aug. i6. 1920 Ripening and Storage of Bartlett Pears 477 



storage seasons. For storage at 60° or above — that is, ccmmon storage — 

 the earliest pickings gave the longest storage season; but when the lower 

 temperature was used the maximum season was obtained in the later 

 picks of more fully matured fruit. This agrees with Stubenrauch and 

 Ramsey in their precooling work. No important correlation could be 

 established between specific gravity of the juice and time of picking, or 

 between starch, as shown by iodin test, and time of picking. Chemical 

 analyses for sugar, acid, and moisture, made under rather unfavorable 

 conditions, were also rather conflicting in results but showed a tendency 

 toward an increase in sugar as the season advanced. 



Further work {16) carried on in the Rogue River region gave further 

 detailed evidence of marked increase in size of the fruit during the picking 

 season. The influence of time of picking and temperature of storage 

 upon keeping quality correlated closely with that obtained the year 

 before. A "pressure test," or the measure of the amount of pressure 

 necessary to make a depression of certain size in a pear at various stages 

 of development and maturity was followed through the season; and a 

 marked correlation was established between the time of picking and the 

 resistance of the fruit to pressure, the resistance growing less the longer 

 the fruit remained on the tree. 



Some work has been done recently on the effect of storing Bartlett 

 pears at high temperature. Shamel {14) placed a box of pears in a lemon- 

 curing room, held at a temperature of about 90° F. and at a humidity 

 averaging 85° to 90°. The pears kept perfectly and without ripening for 

 a month. Upon removal from the storage they ripened normally and 

 were of good quality. Shamel attributed these results to the high 

 humidity. 



Taylor and Overholzer {16), following Shamel's work, stored small lots 

 of Bartletts at temperatures ranging fron 69° to 104° F., with one lot at 

 32° storage as a control. High humidity and normal dryness of air were 

 compared at each temperature. Fruit held at 69° to 85° ripened most 

 quickly. When the storage temperature was above 85°, the ripening of 

 the fruit was retarded. Fruit stored at 104° was two to three weeks later 

 in ripening than that stored at 85°. Humidity had no effect other than 

 that of preventing shriveling at the high temperatures. 



From a summary of all the storage work that has been done on Bartlett 

 pears it is apparent that the lower the temperature used, down to 31° or 

 32° F. — the lowest temperatures of storage used in these experiments — the 

 longer the storage season will be. Most rapid ripening is attained at a 

 temperature of 70° to 80°, while either higher or lower temperatures tend 

 to retard ripening. It is not definitely known just why these higher 

 temperatures should retard ripening, but it is of interest to note that 

 many of the processes concerned v/ith the ripening of fruit are chem- 

 ical reactions brought about by enzym action. It is well known that 

 there are minimum, optimum, and maximum temperatures for enzym 



