124 
Journal of Agricultural Research 
Vol. XXIX, No. 3 
were exposed to the low temperatures 
and were read every 24 hours. In this 
way an estimate of the temperature 
conditions in the whole lot was ob¬ 
tained. While this practice is not so 
satisfactory as readings at shorter inter¬ 
vals, the temperature changes in frozen 
apples while ice is being formed are 
rather slow at the freezing room temper¬ 
atures used, so the method proved satis¬ 
factory (Table XVII). 
of a thoroughly frozen apple. The 
acidity in a few instances shows a 
decrease from that found in unfrozen 
apples, but it is slight and irregular, 
and not significant. 
Since the differences noted above 
are small, although distinct enough so 
that they seem noteworthy, another 
series of experiments was made on 
apples subjected to temperatures which 
remained between 26° F. and 26.5°. 
Table XVIII.— Effect of freezing, at a temperature just below their freezing point , 
on the softening of Winesap and Yellow Newtown apples, as measured by the 
pressure tester, and on the acidity and amount of visual injury found 
Periods of exposure to freezing 
temperatures 
Period and temperature of subsequent 
storage 
Pressure in pounds 
necessary for 
puncture 
Percent¬ 
age 
acidity 
as malic 
acid 
Pared 
Unpared 
WINESAP 
None___ 
None____ 
13. 9 
19.0 
0. 560 
Do.... 
24 hours at 65° F.. 
13.2 
17. 6 
. 528 
24 hours__ 
_do__ 
13. 6 
18. 5 
. 548 
48 hours _ _ 
.do. ... 
12. 8 
17. 4 
. 550 
72 hours__ 
_do.. . 
13.1 
16.9 
. 557 
None ..... 
2 Yi weeks at 32°... 
13. 6 
17. 7 
.529 
24 hours_... _ 
-__I_do....... 
13.2 
17.2 
48 hours___ 
_do_____ 
12.6 
17. 5 
. 517 
72 hours . _ 
_do___ 
12.7 
17.6 
.550 
YELLOW NEWTOWN 
N one_ __ _ 
None_ 
16. 2 
23.4 
0. 570 
Do . . 
24 hours at 65° ___ 
15.7 
22.3 
. 514 
24 hours _ ___ 
_do___ 
15. 9 
23. 6 
. 519 
48 hours 
__do.____ 
14.8 
22. 6 
•. 543 
72 hours _ 
_do__ 
14.4 
21. 3 
. 558 
None _ 
2^ weeks at 32° .... 
13.8 
21.6 
.526 
24 hours _ _ _ _ 
.....do__- 
13. 6 
21. 2 
48 hours _ 
_do_ 
13.2 
21.0 
.499 
72 hours _ 
_do...... 
13.6 
21.3 
.513 
The average freezing point of the 
Winesap apples used in this experi¬ 
ment was 28° F. and of the Yellow 
Newtown apples 28.8°. The read¬ 
ings at the 72-hour period indicate that 
the apples were still at their freezing 
point at that time, or very near it, as 
they probably were also at the 48- 
hour period, though the amount of ice 
in the tissue had undoubtedly increased. 
Table XVIII presents the pressure 
test and acidity figures for sample 
lots of these apples withdrawn at 
24-hour intervals when the tempera¬ 
tures were read. The storage and 
testing procedure was similar to 
that used in other experiments of the 
same general character. No visual 
injury was detected. 
As in the experiments conducted at 
temperatures around 22° F., there is 
indication that the softening of apples 
is hastened by freezing. Although the 
differences are slight, the amount of 
ice formed in the apples held at a 
temperature just below the freezing 
point may be small, and none of the 
fruit was in the hard wrinkled condition 
Five Virginia varieties, which had 
been held at 32° F. about seven 
months, were used. Acidity determi¬ 
nations were made only for the first 
Table XVII.— Internal temperatures 
of 5 Winesap and 5 Yellow New¬ 
town apples exposed to a temperature 
just below their freezing point for 
different lengths of time 
Apple No. 
24-hour 
48-hou 
72-hour 
period 
period 
period 
WINESAP 
o F 
°F 
op 
I.... 
29.0 
28.5 
28.0 
2... 
29.0 
28.5 
28.0 
3... 
28.5 
28.5 
28.0 
4___ 
28.5 
28.0 
28.0 
5_ 
29.0 
28.0 
28.0 
YELLOW NEWTOWN 
1 ... __ 
29.5 
28.5 
28.5 
2.... 
29.0 
29.0 
28.5 
3--..... 
29.0 
29.0 
29.0 
4__ 
29.5 
29.5 
28.5 
5. 
29.0 
29.5 
28.0 
