Jan. 5, 1924 
Physiological Studies on Apples in Storage 
7 
one week before testing. Initial tests on these varieties were lower than 
those following, probably because of this treatment. Under conditions 
prevailing during these tests, Ben Davis, Winesap, and Rome Beauty all 
softened very rapidly, and Delicious somewhat more slowly. The month 
of September, 1922, was very warm and dry at Arlington, Va., and Octo¬ 
ber was practically without precipitation and moderately warm. Bur¬ 
roughs (5) found that Wagener apples growing on young trees in northern 
Pennsylvania softened only very slowly during September and October. 
These trees had received nitrate fertilizer and were very vigorous. It is 
not known whether the rate of softening while on the tree is primarily a 
variety characteristic or whether it varies largely with environmental 
factors. 
In general, the harder the fruit is at time of picking and placing in 
storage the firmer it will be when removed from storage and exposed to 
market conditions. A firm, hard fruit, sufficiently well colored to be 
attractive, and sufficiently well ripened to be of high quality, and to es¬ 
cape storage scald, is the ideal for storage. High quality and skin condi¬ 
tion associated with resistance to storage scald can be obtained only at the 
-expense of a softening of the fruit. There is much need for a more exact 
knowledge of the influence of such factors as temperature, soil moisture, 
fertilizers, age and vigor of the trees, size of crop, etc., upon the rate of 
softening of the fruit. It is highly desirable that the fruit when picked 
be as firm as it is possible to secure it. 
CHEMICAL CHANGES IN APPLES ASSOCIATED WITH RIPENING ON THE TREE 
Numerous analyses have been made of the chemical composition of 
apples and other fruits at various times during their development on the 
tree. While the actual percentages of the various constituents will vary 
widely, depending upon the variety, locality, cultural conditions, and 
many other factors, the general changes have been well established and 
will be briefly reviewed. These changes may be considered under the 
following subjects: (1) Changes in total acidity, (2) changes in the sugar 
and starch content, (3) changes in the pectin content, and (4) changes in 
the moisture content of the fruit. 
CHANGES IN TOTAE ACIDITY ASSOCIATED WITH RIPENING ON THE TREE 
For more than a century, acidity changes in fruits have attracted wide 
attention, and many conflicting opinions have been held concerning the 
source of fruit acids, as well as their disappearance. This literature has 
been thoroughly reviewed by Bigelow, Gore, and Howard ( 2 ). Because 
of the limited chemical knowledge and the widely varying conditions under 
which early writers on this subject worked, many of their results are un¬ 
trustworthy. Only the more recent contributions will be discussed here. 
Browne (4) analyzed Baldwin apples and found a marked decrease in 
acidity at intervals from August 7 until December 15, when recorded as 
percentage of the wet weight of the apple. Gerber (12) reported a similar 
decrease in percentage composition, but pointed out the fact that the total 
amount of acid per apple increases rather than decreases as the season 
advances, the apparent decrease being more than counteracted by the 
increase in size of the fruit. Finally Bigelow, Gore, and Howard (2) in a 
very complete series of analyses on both summer and winter varieties of 
apples, found the percentage of acid to drop very rapidly from June until 
