Aug. 1, 1924 
Freezing Injury of Apples 
123 
fruit necessarily include the resistance 
of the skin to rupture, which may 
possibly not be affected even in severe 
cases of freezing injury. 
The data indicate a progressive 
softening in apples that have been 
frozen for increasingly longer periods 
of time, both when they were tested 
after 24 hours and when they had been 
in cold storage a month. Comparison 
of the pressure tests and the amount of 
visual injury show that appreciable 
softening can be detected at periods 
when visual injury is quite negligible in 
any particular lot. This indicates that 
apples are actually softened by the ice 
formation incident to freezing, and are 
softer and more mealy following thaw¬ 
ing, even though no visual injury has 
with Yellow Newtown apples discussed 
above, except that at each removal 
hour one sample lot was placed in 65° 
for a week (Table XVI). 
The data are similar in character to 
those obtained for the Yellow Newtown 
apples, and show that as the periods 
during which the apples are frozen and 
held at freezing temperatures are 
lengthened, the fruit is softer upon 
thawing. It probably is also true that 
softening during subsequent storage is 
hastened by the freezing injury. It is 
noticeable that the visual injury and 
the pressure-test figures do not show 
increases of similar degree, and that 
softening occurs when visual injury is 
not present. The increase in acidity 
noted during storage is probably only 
Table XVI.— Effect of freezing at temperatures around 22° F. on the softening of 
Ben Davis apples in lots of 20, as measured by the pressure tester, and on acidity 
and amount of visual injury found 
Period of exposure 
to freezing tem¬ 
peratures 
Period and temperature 
of subsequent storage 
None 
None _ __ _ 
Do. 
24 hours at 65° F_ 
8 hours „ _ 
__do -_ ___ 
16 hours . 
__do_ 
24 hours 
do_ ___ 
32 hours 
do_ 
41 hours 
do _ 
48 hours _ 
...do_ 
None_ 
1 week at 65°. _ _ 
8 hours_do 
16 hours_do. 
8 hours_do_ 
16 hours_do_ 
24 hours_do_ 
32 hours_do_ 
41 hours_do_ 
48 hours_do_ 
None_ 1 month at 32° 
8 hours_do_ 
16 hours_do_ 
24 hours_ do_ 
32 hours_ do_ 
41 hours_do_ 
48 hours_,do_ 
Pressure in pounds 
necessary for 
puncture 
Percent¬ 
age 
acidity 
as malic 
acid 
Number of apples show¬ 
ing visual injury 
Pared 
Unpared 
None 
Trace 
Severe 
12.1 
12.4 
15.6 
17.4 
0.412 
.396 
11.1 
15.5 
.425 
16 
2 
0 
11.5 
15.5 
.435 
16 
3 
1 
9.7 
13.7 
.411 
17 
3 
0 
11.1 
14.6 
.433 
20 
0 
0 
10.7 
14.6 
.436 
20 
0 
0 
10.7 
11.0 
15.3 
16.3 
.448 
.349 
16 
4 
0 
11.1 
15.4 
.450 
20 
0 
0 
10.8 
14.3 
.397 
14 
4 
2 
10.7 
14.6 
.406 
13 
2 
5 
10.3 
14.0 
.418 
16 
1 
3 
9.8 
13.7 
.421 
16 
1 
3 
8.5 
10.5 
12.6 
15.3 
.308 
10 
3 
7 
10.7 
14.5 
.407 
20 
0 
0 
10.5 
12.9 
.377 
14 
3 
3 
10.0 
13.5 
.375 
12 
3 
4 
9.8 
12.9 
.356 
16 
0 
4 
1 9.6 
13.3 
11 
1 
7 
1 9.1 
11.7 
.378 
14 
1 2 
1 
4 
occurred. This means that frozen 
apples are nearer to the end of their 
storage life. They can not be held so 
long as unfrozen fruit and be in good 
condition for merchandising after re¬ 
moval from storage. 
The acidity changes show a distinct 
but irregular decrease with freezing in 
the case of the Yellow Newtown apples. 
This irregularity may be due to varia¬ 
tions in the samples, for distinct 
variations occur even in unfrozen lots. 
Another experiment was carried out 
with Ben Davis apples which had been 
held about five months in 32° F. They 
were subjected to freezing tempera¬ 
tures at about 22° for different periods 
of time. The procedure was the same 
as that employed in the experiments 
apparent, and may result from a loss of 
water from the tissues, since the acidity 
is calculated to the wet weight of the 
tissues. 
The above experiments were carried 
on at temperatures distinctly below the 
freezing points of the fruit used. In 
order to determine whether changes oc¬ 
cur at temperatures just below the 
freezing point, tests were made on Wine- 
sap and Yellow Newtown apples grown 
in Virginia which had previously been 
in storage at 32° F. nearly six months. 
The two varieties were tested at the 
same time, with the freezing room held at 
temperatures ranging from 27° to 28°, 
except for a short period of 26° at the 
beginning. Fruit thermometers were 
inserted in scattered apples when they 
