Aug. 1, 1924 
Freezing Injury of Aggies 
101 
the tissues. Mtiller-Thurgau was the 
first to insist that ice formation in the 
tissues was a necessary precedent to 
injury, and this opinion is held quite 
generally. It seems true, also, that a 
certain amount of ice formation can 
occur in apples (6) without injury. 
In other words, there must be a distinc¬ 
tion made between apples which are 
frozen and those which are frozen to 
death, as apparently there are various 
degrees of freezing injury in frozen ap¬ 
ples. 
In the undercooling experiments, 
apples of several varieties were sub¬ 
jected to low temperatures and left 
undisturbed, so that undercooling took 
place. Temperatures were read at 
intervals until the desired low tempera¬ 
ture had been reached, after which the 
apples were removed and allowed to 
become warm without ice formation 
ever having taken place. 
Table II .—Data showing temperatures 
to which apples were undercooled, 
temperature of the air surrounding 
the apples, and number of apples 
showing visual injury 
Tem¬ 
Air 
Tem¬ 
Air 
f 
pera¬ 
tem¬ 
pera¬ 
tem¬ 
i 
| 
ture 
to 
pera¬ 
ture 
Visual 
injury 
ture 
to 
pera¬ 
ture 
1 
j Visual 
which 
at 
which 
at 
injury 
under- 
under¬ 
under- 
under¬ 
cooled 
cooling 
cooled 
cooling 
i 
WINESAP FROM YAK¬ 
YELLOW NEWTOWN 
IMA, WASH. 
FROM 
HOOD 
RIVER 
0 F. 
o p 
1 
oreg. — Continued 
23.5 
20*7 
None. 
op 
op 
23.5 
20.6 
None. 
24.0 
22.2 
None. 
23.5 
20.4 
None. | 
24.0 
21.9 
None. 
23.4 
23.0 
None. 
23.8 
22.8 
Noge. 
23.4 
23.0 
None. ! 
23.4 
23.0 
None. 
23.0 
22.4 
| None. 
23.4 
23.0 
None. 
22.8 
20.4 
None. 
23.0 
22.4 
None. 
22.6 
20.4 
None. 
23.0 
22.3 
None. 
22.6 
17.1 
None. 
23.0 
22.2 
None. 
22.5 
19.6 
None. 
23.0 
21.4 
None. 
22.3 
19.2 
None. 
22.9 
22.4 
None. 
22.2 
20.4 
None. 
22.6 
21.9 
None. 
22.2 
20.4 
1 None. 
22.5 
21.9 
None. 
22.0 
20.5 
i None. 
22.5 
21.9 
None. 
21.8 
18.0 
None. 
21.8 
• 
None. 
21.5 
20.5 
None. 
21.6 
None. 
21.3 
20.0 
None. 1 
20.3 
16.5 
None. 
21.2 
15.5 
(°) 
DELICIOUS FROM OP¬ 
21.0 
15.0 
None. 
PORTUNITY. WASH. 
20.2 
20.2 
20.0 
20.0 1 
None. 
None. 
22.2 
22.0 
21.8 
21.8 
None. 
None. 
YELLOW NEWTOWN 
21.9 
21.8 
None. 
FROM 
HOOD 
RIVER, 
19.8 
15.2 
(“) 
OREG. 
25.0 
23.0 
None. 
GRIMES 
GOLDEN FROM 
ARLINGTON. 
VA. 
25.0 
25.0 
25.0 
22.6 
22.5 
22.3 
None. 
None. 
None. 
23.7 1 
23.1 | 
23.6 j 
22.3 i 
None. 
None. 
25.0 
21.3 
None. 
ROME 
BEAUTY 
FROM 
24.7 
23.0 
None. 
ARLINGTON, 
VA. 
24.0 
23.6 
None. 
22.2 
21.4 
None. 
24.0 
23.0 
None. 
22.7 
21.4 
None. 
24.0 
22.9 
None. 
° Some injury not near thermocouple. 
With two exceptions, no injury re¬ 
sulted, and in these the damaged area 
was not immediately adjacent to the 
thermocouple. Examination of sup¬ 
posedly frozen apples has shown that 
there may be frozen areas in various 
parts of the fruit, separated by areas 
in which apparently little or no ice 
has formed. If the thermocouple is 
located in one of the latter, it may not 
record exactly the condition of ice 
formation throughout the apple. 
Though no visual injury was apparent 
in such apples, changes which could 
not be detected by careful inspection 
might nevertheless be taking place. 
The low temperature to which apples 
can be undercooled without injury, 
provided they are not disturbed, is 
very striking. Inoculation of apples 
sometimes takes place with compara¬ 
tive difficulty, so it is possible to 
bring their temperature seven or eight 
degrees below their freezing points and 
to hold them there for some time with¬ 
out the formation of ice. Since apples in 
transit are subjected to motion most 
of the time, the possibility of any con¬ 
siderable undercooling is slight. As 
the temperature drops below their 
freezing points it may be that such 
apples begin to freeze gradually, pos¬ 
sibly by successive inoculations or dis¬ 
turbances producing small increments 
of ice in the tissues. Such a phenome¬ 
non is occasionally observed in apples 
which are entirely undisturbed, but 
this involves other causes not now defi¬ 
nitely known. 
EFFECT OF UNDERCOOLING AS DETER¬ 
MINED BY THE PRESSURE-TEST 
METHOD 
Since data from other experiments 
show that one effect of freezing apples 
is to make them softer and more mealy, 
apples of two varieties were under¬ 
cooled and tested with a pressure¬ 
testing apparatus similar to that de¬ 
scribed by Murneek ( 8 ), which deter¬ 
mines the hardness of the fruit. In 
tests with this apparatus the skin of 
the apple was removed from an area 
of about three-quarters of an inch in 
diameter at three equidistant points 
about the circumference of the fruit, 
and the test made of the number of 
pounds of pressure required to force 
a smoothly rounded plunger seven-six¬ 
teenths of an inch in diameter into the 
flesh of the fruit for a distance of five- 
sixteenths of an inch. Tests were also 
made on the same apples with the 
skin intact; but it has been found that 
tests directly on the flesh of the apple 
are a more accurate index of the real 
condition of the fruit as regards rela- 
