A. J. MACDONALD AND T. S. KRISHNAN 31
specks of blood. From the market standpoint
such eggs, though not of the highest quality, can
be considered as edible.
SHRINKAGE
Shrinkage in eggs is brought about by the loss
of moisture and is regulated by the temperature
and humidity of the atmosphere. In commercial
marketing it is impossible to determine the shrink-
age direct, but an indirect measurement of shrink-
age can be made by studying the size of the air
space as seen by means of the candling lamp. The
maximum permissible air cell depth for Agmark
as laid down in the Agricultural Produce (Grading
and Marking) Act (1937) is three-eighths of an inch
[Report on Marketing, 1938]. As judgment of the
air cell depth under the candling lamp is somewhat
empirical, 240 fertile and 240 infertile eggs were
broken and the size of the air cell measured by
means of a spherometer Plate III, Fig. 2). The
various measurements for the depth of the air cell
and the percentage losses of weight from the
original weights as measured by actual weighings
are recorded in Table II.
TABLE II
Shrinkage
Period of
storage
Fresh . .
3 days . .
7 days . .
10 days . .
14 days . .
Place of
storage
...
Cooler .
Room .
Cooler .
Room .
Cooler .
Room .
Cooler .
Room .
Hour-old eggs
Depth of
air cell
mm.
1.1
4.9
6.1
6.3
8.6
7.1
9.9
7.6
12.5
Loss of
weight
per cent
...
0.78
1.76
1.91
3.99
2.54
5.73
3.39
9.24
Day-old eggs
Depth of
air cell
mm.
4.3
5.2
7.0
6.8
9.6
7.3
11.2
7.8
13.2
Loss of
weight
per cent
0.55
1.68
1.59
4.61
214
6.94
2.92
9.90
At hour-old the average depth of the air cell
was only 1.1 mm. whereas in day-old eggs stored
under room conditions the corresponding figure
was 4 3 mm. In all cases the depth of the air
cell increased with storage; the figures for the
hour-old and day-old eggs held under room condi-
tions for 14 days were 12.5 and 13.2 mm. res-
pectively. The increase in the depth of the air
cell under cabinet conditions was much less and
after 14 days of storage the corresponding figures
were 7.6 and 7.8 mm. for the hour-old and
day-old eggs respectively.
The percentage loss of weight followed much
the same trend as the air cell depth for at each
stage the hour-old and day-old eggs in the cabinet
had shrunk less than those under room conditions.
At 14 days storage the percentage losses in weight
in the hour-and day-old eggs were 9.24 and 9.90
whilst the corresponding figures for the cabinet
stored eggs were only 3.39 and 2.92 respectively.
Shell thickness determinations were made on all
the stored eggs in order to find out if there was any
correlation between the thickness of the shell and
the percentage loss of weight. Micrometer screw
gauge readings of the thickness of the shell were
made on each egg at each pole and at a point mid-
way between the poles and these figures were
averaged to get the shell thickness. A critical
examination of the results obtained revealed no
close relationship between the shell thickness and
percentage loss of weight with shells ranging in
thickness from 0.22 to 0.45 mm.
Table III gives comparative figures for the
percentage losses in weight for a dozen selected
pairs of eggs. Both eggs in each pair were treated
identically. The figures showed that the per-
centage loss in weight is not correlated with the
thickness of the shell. This is in agreement with
the findings of Romanoff [1937].
TABLE III
Relation of shell thickness to percentage loss in
weight
No.
1
2
3
4
5
6
7
8
9
10
11
12
Shell thickness
mm.
0.26
0.26
0.27
0.27
0.29
0.30
0.31
0.32
0.33
0.34
0.34
0.34
0.34
0.35
0.34
0.36
0.34
0.38
0.36
0.43
0 37
0.38
0.38
0 38
Loss of weight
per cent
1.57
3.02
5.42
7.62
6.21
7.62
9.28
13.00
4.89
9.06
2.90
4.94
1.22
2.10
4.87
9.79
4.39
10.04
5.65
8.65
3.55
6.39
4.58
10.58