32
An Egg-cooling Cabinet
INTERIOR QUALITY
The question of the interior quality of the yolk
and white, apart from embryo development, was
also investigated. The quality factors studied
were albumen index, percentage thick white and
yolk index as described by Macdonald and
Krishnan [1942, 1943]. Table IV gives data for
hour-old eggs stored in May and Table V gives data
for day-old eggs stored in June. As the average
temperatures both in the room and cabinet were
somewhat higher in June than in May, the two
tables cannot be regarded as strictly comparable.
Under room conditions the yolk index figures for
the fertile hour-old eggs decreased from an initial
0.433 to 0.229 at seven days. During the same
period the rate of decline in the infertile eggs also
was very similar. From seven days onward the
rate of decline in the yolk index figures was
greater in the case of the fertile than the infertile
eggs. Whilst it was possible to make yolk index
determinations on all the samples of infertile eggs
stored at room conditions for 10 and 14 days, it was
only possible to make two determinations in the
case of the fertiles at 10 days and none at 14 days.
The yolk index figures for the fertile and infertile
eggs were fairly comparable under cooler conditions.
Yolk index determinations were made on all 12
samples of fertile eggs held in the cooler for 14
days. The yolk index figures at each stage of
storage were higher in the cooler than in the room.
In the case of the day-old eggs the yolk index
figures were similar for fertile and infertile eggs held
for three days under room conditions. However at
seven days and at each subsequent period under
room conditions all the fertile eggs had burst yolks
whereas it was possible to record all the yolk
index figures of 7 and 10 days and 8 out of 12 at 14
days of the infertiles held under the same
conditions.
As in the case of the hour-old eggs the day-old
eggs stored under cooler conditions gave better
results as judged by yolk index than the eggs
stored under room conditions. In the case of
fertile eggs it was possible to determine the yolk
index of all eggs at seven days in the cooler
whereas no readings were possible at this stage on
fertiles held under room conditions.
The albumen quality factors, viz. albumen
index and percentage thick white show that the
conditions in the cooler were not so favourable
to their preservation as in the case of the yolk
index. There was also less difference in the be-
haviour of the fertile and infertile eggs both under
room and cooler conditions of storage. Readings
for the albumen index were often impossible on
account of rupture of the thick white layer.
Rupture of the yolk in fertile eggs also seriously
interfered with the recording of data. The thick
albumen layer was ruptured in nearly all the fertile
eggs at three days in the day-old lot and at seven
days in the hour-old lot, when held at room tem-
perature. The fertile eggs in the cooler had the
thick albumen intact for about 3 days longer than
those in the room. Under the cabinet conditions
the albumen index figures were somewhat better
than those obtained under room conditions.
TABLE IV
Interior egg quality—hour-old eggs
Period of
storage
Fresh
3 days .
7 days
10 days .
14 days .
Place of
storage
. .
Cooler . .
Room . .
Cooler . .
Room . .
Cooler . .
Room . .
Cooler . .
Room . .
Yolk index
Fertile
0.433
0.386
0.349
0.314
0.229
0.284
(2)
0.140
0.239
Infertile
0.433
0.401
0.330
0.350
0.234
0.292
0.179
0.271
0.165
Albumen index
Fertile
0.096
0.056
0.041
(6)
0.050
(1)
0.025
(4)
0.036
(2)
0.024
Infertile
0.103
0.048
0.044
(7)
0.036
(5)
0.032
(7)
0.032
(4)
0.030
(2)
0.034
(1)
0.046
Percentage thick white
Fertile
63.5
53.8
54.1
47.8
52.1
49.6
..
39.9
..
Infertile
65.0
52.4
51.8
52.8
52.4
47.7
46.4
42.4
40.8