SHELL SEALING OF EGGS
By T. S. KRISHNAN, Poultry Research Section, Indian Veterinary Research Institute, Izatnagar
(Received for publication on 16 June 1947)
(With one text-figure)
T HE efficiency of lime and water-glass for egg preservation under Indian conditions was studied
by Macdonald and Krishnan [1943]. The preservative action of these substancer is generally
attributed to the sealing of the egg shell pores; which ensues during the storage in their solution.
An attempt has been made to determine the minimum time required to effect this.
An increase in size of the egg air-cell is due to evaporation of water from the egg contents, which,
other factors remaining the same, depends on the porosity of the egg-shell. In this work it has been
assumed that the degree of shell-sealing is inversely proportional to the increase in air-cell depth,
i.e., the more complete the sealing, the smaller the increase in air-cell size and vice versa.
Day-old infertile eggs were soaked for varying periods in lime-water and water-glass, prepared
as usual [Macdonald and Krishnan, 1943], and then put into an incubator at 100°F. along with an
equal number of similar but untreated eggs. After seven days storage, lots of twelve eggs were taken
from each of the above series and the depth of the air-cell in each egg was measured (see Table I).
TABLE I
Average air-cell depth in eggs, treated in different ways, after seven days storage at 100°F.
Period of immersion in preserving liquid
6 hours
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12 hours
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13 hours
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24 hours
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48 hours
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72 hours
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96 hours
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120 hours
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Depth of air cell (mm.)
Lime-water
treated
6.5
5.8
5.2
5.3
5.1
5.3
5.1
5.1
Water-glass
treated
11.3
10.2
10.5
11.2
10.0
9.6
8.6
9.0
Untreated
10.9
11.0
10.8
11.2
11.2
10.9
11.0
11.2
N.B.—The initial depth of air-cell in fresh day-old eggs was 4.5 mm.
The untreated eggs showed an average increase of 6.5 mm. in air-cell depth after seven days at
100°F. Under similar conditions of storage, the increase in air-cell depth in eggs soaked in water-
glass for five days was. 4.5 mm., as compared with 2.0 mm., 1.3 mm., and 0.7 mm. observed in eggs
immersed in lime-water for 6, 12 and 18 hours respectively. Even after 120 hours soaking in lime-
water the increase in air-cell size was almost the same as after 18 hours immersion. Hence it seems
that the sealing action of lime-water was nearly complete in about 18 hours. Treatment for only
six hours with lime-water would appear to be much more effective than five days with water-glass.
Even after nine days immersion in water-glass the sealing was only partial as indicated by an increase
of 3.5 mm. in air-cell depth. It would therefore appear that the minimum time required for sealing
the shell pores in eggs steeped in lime-water is about 18 hours. The action of water-glass seems to
be comparatively very slow since only partial sealing resulted even after nine days treatment.
In the case of lime-water the sealing is perhaps due to the deposition in the shell-pores of insoluble
CaCO 3 formed by the interaction of Ca(OH) 2 of the lime-water and CO 2 present inside the egg. Since
this chemical action is completed quickly, shell-sealing in lime-water takes place rapidly. This
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