A PRELIMINARY NOTE ON SOME INDIGENOUS METHODS OF EGG
PRESERVATION
By T. S. KRISHNAN, B.A., M.Sc., A.I.C., Poultry Research Section, Imperial Veterinary Research
Institute, Izatnagar
(Received for Publication on 29 April 1942)
(With Plate X)
FOWLS do not, as a rule, lay eggs at an even
rate throughout the whole year. In northern
India, the highest production generally occurs
from January to April. Thereafter, the rate
declines with the approach of summer months
and, though there may be a slight rise in the
monsoon (July and August) if the birds are pro-
perly protected from the rains, there is a tendency
for a general decline in production until they stop
laying during the moult. The moulting period
varies somewhat with the breed but in North
India it generally occurs between the months of
September and December. Pullets begin to lay
at different times according to their date of hatch
but, on the average they do not come into maxi-
mum production until about February. The older
birds, too, starting to lay after the moult, reach
their peak production at about the same period.
In many northern countriew ith a well organized
and thriving poultry industry, the egg production
during the spring months is generally in excess of
current requirements. On the other hand, during
autumn and early winter months the production
is usually less than the demand. Consequently,
eggs are much more expensive during the latter
period than the former. Taking advantage of
this price variation, marketing agencies in those
countries put the surplus eggs of the spring months
into cold storage and release them later when
prices are high, thus making available a regular
supply of good eggs all the year round. In India,
however, there is no large seasonal surplus in
production and consequently the average price of
eggs is not subjected to violent fluctuation.
During the hot months of May and June the
demand is generally low, owing to the common
belief that eggs constitute an unsuitable diet in
hot weather and also to the very poor quality of
the average market egg. Consequently, the prices
are not high in spite of the comparatively low
production at this season. The prices during the
period of high production (January to March) are
generally better than during the hot weather,
probably because of the heavy demand and the
better quality of the eggs. Hence, there is little
scope in India, under existing conditions, for large-
scale cold storage of eggs as practised in many
other countries.
Nearly all eggs are of excellent quality when
new-laid but they are highly perishable and
deteriorate rapidly unless proper precautions are
taken to conserve their initial quality. If eggs
are kept under ordinary atmospheric conditions,
they develop enlarged air cells due to a loss of
moisture and the shrinkage of the internal con-
tents. In the hot weather especially, the thick
jelly-like albumen deteriorates and becomes
watery. At the same time water from the albu-
men begins to enter the yolk causing it to increase
in size and weakening the surrounding vitelline
membrane. On account of these changes, the
yolk, which should stand up well-rounded in the
centre of a compact layer of firm albumen, flattens
out or even ruptures in an egg which has been left
too long in a warm atmosphere. Since the carbon-
dioxide tension in the outside atmosphere is lower
than that inside a new-laid egg, there is a gradual
loss of this component from the egg, with the
result that the albumen becomes more alkaline.
This hastens the rate of the deteriorative changes.
Also, if the temperature at which the egg is stored
is above 68°F., the embryo in fertile eggs begins
to develop. Since the temperatures prevalent in
the plains of India during the hot weather are
very high, being not far from the optimum in-
cubation temperature of eggs, rapid embryo
development occurs in fertile eggs under normal
storage conditions. During this season, if fertile
eggs are left at ordinary room temperature for
even a week, they generally become inedible on
account of embryo development.
All the above-mentioned physical and chemical
changes are considerably slowed down by keeping
the eggs at a temperature below 60°F., embryo
development ceasing below 68°F. Though humi-
dity, air circulation, carbon-dioxide concentra-
tion, cleanliness of eggs and packing materials also
affect the keeping quality of eggs, the most im-
portant consideration is the provision of a properly
adjusted cool temperature in the storage room.
Since the vast bulk of eggs marketed in India
are fertile, the importance of keeping them cool
during the hot weather to prevent large scale
damage by embryo development is obvious.
Since, however, the poverty of the producer as
well as the low price of eggs make the use of a
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