Quick study of egg preservation and processing

1. PRESERVATION AND PROCESSING
OF EGGS
Date: 25.02.2021

2. Preservation of Eggs
• As egg is fragile and perishable commodity ,it
should be handled carefully and marketed as
soon as possible.
• The method of preservation of shelled eggs are
based on the principle of retarding the microbial
growth by sealing the pores of the shell to
minimize the evaporation of moisture and gases,
thus reducing the physico-chemical changes in
the egg contents for a reasonable length of time.

3. Shell egg preservation
• Dry packaging : Eggs are kept in earthen pots with
clean dry packing material and pot is buried in
wetland. This method is practiced in remote areas
particularly rural villages where the access to
modern method of preservation is very poor.
• Thermal treatment: This method involves the
application of heat and includes flash heat
treatment and thermostabilization.Sometimes the
latter is followed by simultaneous oil coating for
more effective preservation.

4. • Flash heat treatment: The eggs are immersed
for five seconds in boiling water.
• The advantage of this method is that it
destroys some of bacteria present on shell
surface and does not require any thermostatic
control to maintain specific temperature.
• In this method a thin film of albumen
coagulates beneath the shell membrane
which seals the shell pores internally

5. • Thermo stabilization:
• This method is good for fertile eggs since it
kills the embryos and therefore is also known
as defertilization method.
• It essentially consists of immersing shell eggs
in hot water at 130 degree Fahrenheit/45
degree celsius for 30 minutes, 54 deg celsius
for 15 minutes or 56 deg celsius for 10 min or
56 deg celsius for 10 min or 60 deg celsius for
5 min which tend to coagulate the albumin
and eggs are cooled under tap water

6. Immersion in preservative solutions
• Lime water
• Water glass method
• Oil coating

7. Lime water
• Lime water is prepared by mixing about 0.5 kg
of quick lime (calcium oxide) in about 1 litre of
boiling water.
• The mixture is left to settle overnight and
clean supernatant, liquid is poured into jar.
• Sodium chloride 112 gms per litre may also be
added to increase the specific gravity of water
and minimizes chances of breaking of eggs

8. • To this solution 2.5 litres of cold water is
added and filtered through muslin cloth.
• Eggs meant for preservation should be kept in
a jar or earthen pot and pour the lime
solution over the eggs till all the eggs are
completely immersed.
• A little mineral oil may be added over this
layer to prevent evaporation.
• Eggs have to kept for 24 hours in this solution

9. • After 24 hours they are taken out,dried and
arranged in filler flats.
• Eggs can be stored in this method for 2-3
months in a good edible condition at normal
ambient temperature.
• The preservative effect of lime water is mainly
due to the deposition of a thin film of calcium
carbonate on the shell surface which partially
seals the pores.

10. Water glass method
• At 10 per cent solution of sodium silicate is prepared in
hot water and allowed to cool.
• The cooled solution is then poured into a jar containing
eggs till they are immersed completely.
• The jar is covered and kept in a cool place where the
temperature should not be above 70 deg F.
• The eggs are dipped for 12 hours in this solution,then
taken out and dried at room temperature
• In this process a thin precipitate of silica deposited on
the surface of the shell seals the pores.

11. Oil coating
• It preserves the egg by forming a thin film of
oil in the surface of the shell to seal the pores.
• The eggs should be oil treated within few
hours of laying so as to retain better interior
quality.
• Dirty eggs should be washed before oil
coating.

12. • The oil used for coating must be
colourless,odourless and having sp gravity
about 0.855 to 0.870 at 15 deg C,viscosity
should be between 70-90 and it should
remain liquid at low temperature.
• Vegetable oil such as cotton seed,linseed and
groundnut oil mixed with an antioxidant
Butylated Hydroxy Toluene(BHT) at 125 ppm
level is a good sealing agent.

13. • The commercial egg treatment oils are :Heavy
paraffin oil,Liquid paraffin,Coconut oil
• The rate of CO2 escape is considerable
reduced in oil immersed eggs and eggs are not
likely to absorb foreign odours.
• Egg can be coated by dipping in oil or spraying
with it.

14. • In oil dipping,eggs held in wire baskets and
dipped in a bath of oil preheated to 45 dg
celsius for 5 to 7 seconds
• The baskets are then taken out and excess oil
is drained off before storage of eggs
• The egg coating oil preheated to 55 deg
celsius ,is sprayed on the broader end of egg
shell where pores are in abundance.

15. Over-wrapping
• For over wrapping of eggs ,polythene
,cellophane ,polyvinylidene and other
transparent ,thin but sufficiently strong films
are used.
• These films should be impervious to gases
and moisture.

16. Cold storage
• An egg storage centre with cold storage
facilities should be prepared designed and
always keep clean.
• It has main sections such as receiving area for
egg brought from the farms ,processing area
for grading and packaging and cold stores for
storing graded and packaged eggs.

17. Pre storage treatment
• Prior to cold storage ,clean eggs are separated
from the dirty egg.
• The latter are washed ,graded and packed
separately.
• All eggs are candled and those having cracked or
unsound shell and interior quality defects should
not stored.
• Eggs of different grades are packed separetely,as
described earlier, first in filler flats and then in
corrugated cardboard egg boxes which are
stacked on the shelves provided in cold store.

18. Cold storage and duration of storage
• The quality of eggs prior to storage as well as
temperature and relative humidity of cold
room determine the period of storage.
• Eggs intended for short storage i.e,about a
month of storage should be stored at 10-12
deg celsius with 75-80 % RH ,whereas long
tem (3 months) they should be stored at 4-6
deg celsius with same RH.

19. • Cold storage temperature should be below -2
deg celsius in order to prevent freezing of
albumen and assisted cracking of shell.
• Similarly,RH of cold store room should not
exceed 85 % to prevent mold growth.

20. Post storage care of eggs
• The egg held in cold store particularly at low
temperature(<8 degree celsius) show
condensation of water on shell surface which is
known as sweating
• Hence, they should be placed in an ante room
maintained at a temperature of 15 to 20 deg
celsius for about 8-12 hours before release to the
market.
• Cold stored eggs should preferably be marketed
within 5 days while oil coated eggs within 10 days
after removal from cold store.

21. Liquid egg preservation
• Freezing and dehydration are the common methods of
preserving quality of liquid egg in terms of frozen and
dried egg products
• Freezing : Low temperature inhibits microbial growth
and some physico chemical reactions and thereby
retains the quality of liquid egg.
• For the manufacture of frozen egg products ,egg liquid
is homogenized, filtered ,pasteurized ,filled in metal
cans or plastic cartons /bags of 2 to 5 kg capacity and
quick frozen at -3o to -40 deg celsius in a blast freezer
before storage at -18 deg celsius for 6-8 months

22. Dehydration
• The removal of water from food inhibits the
growth of micro organisms and slows down
the chemical reactions in the constituents of
food and thus preserved its quality.
• This principal is applied in the production of
dried eggs products from albumen,yolk and
whole egg separately depending upon usages
in food and non food industries.

23. Preparation of Egg Melange
• The process of conversion of shell eggs into
dried egg products consists of washing of
eggs, breaking them individually in cups by
hand or machine, inspection for odour and
blood spot etc,collection of contents as whole
liquid ,albumen or yolk ,homogenization
,filtration,desugarization,pasteurizatuion and
dehydration of egg melange

24. • Filtration is done to remove chalazae ,vitelline
membrane and shell particles, if any ,from liquid.
• Desugaring is the removal of reducing sugar i.e,
glucose from egg liquid by use of either glucose –
oxidase enzyme or bakers yeast in order to
control browning (Maillard reaction) responsible
for discolouration ,off flavour development and
reduction in solubility of dried egg products
during storage .

25. • It is mandatory to pasteurize egg liquids to
destroy all pathogenic microbes including
Salmonella spp and to reduce spoilage organisms
as much as possible before dehydration
• United States Department of Agriculture now
requires that whole liquid egg to be heated to
atleast 60 deg celsius and held for no less than
3.5 min for average particles while United
Kingdom recommended a pasteurization at a
temperature of 64.5 deg celsius for 2.5 min.

26. • In India –liquid eggs are pasteurized at 62.5
deg celsius for 3.5 min
• China –pasteurized at temperature of 62 deg
celsius for 2.5 min

28. Test for Adequacy of pasteurization
• Catalase activity test : It is very useful and
ideal for egg products
• Since catalse activity of white and whole egg is
substantially reduced at 54 deg celsius or
below .
• Hence it is a good indicator of pasteurization
efficiency .

29. Whole egg powder

30. • Small droplets of liquid eggs are produced by
atomizing them and pass through hot air
chamber of spray drier .
• Because of very rapid evaporation ,egg liquid
spray is converted into fine powdered
instantly.