q Egg is a
perishable product having short shelf life.
of eggs should start from the point of production itself.
of eggs at least 3 times daily.
q Using a
clean receptacle with ventilated sides and bottom, preferably filler flats.
handling of eggs during collection and while storing in filler flats etc.,
q Cooling the eggs quickly to 50oF or less
at 75-85% relative humidity.
q Marketing the eggs at least twice weekly.
FOLLOWING CHANGES OCCUR ON STORAGE :
Moisture loss through the pores
Gaseous (CO2) loss
Change of PH
Movement of water from thick albumen to other albumen layers and to yolk
Entry of microbes through the pores
Absorption of foreign odours
THERE ARE TWO TYPE EGG PRESERVATION
q Retarding the microbial growth and
sealing the pores of the shell to minimize the evaporation of moisture and
escape of gases, thus reducing the physico-chemical changes in the egg.
q Sometimes, a combination of methods is
employed for effective preservation.
1.Immeresion in liquid
a) Lime water
b) Water glass method
2. Oil coating
A) LIME WATER
litre of boiling water is added to 1 kg of quick lime.(caco3)
brought to room temperature
4 to 5 litres of cold water 225 g of table-salt are added to it.
To allow the solution to settled down and
filter with muslin cloth
q The eggs are immersed in this clear fluid
for 16 to 18 hours, and then taken out.
q Eggs are dried at room temperature and
transferred to filter flats. The eggs can then be stored for 3 to 4 weeks at
-10 % sodium silicate
q The eggs are left immersed overnight in
q It deposits a thin precipitate of silica on
the surface of egg shell, possesses intrinsic antiseptic properties and does
not impart odour or taste to the eggs.
treating egg with a white, odourless, paraffin base mineral oil used.
the pores with oil .
rate of CO2 escape is considerably reduced and evaporation of water ,loss of egg weight
q Oil treated eggs are kept in cold room.
q If oil treatment is to be effective it should
be done preferably at the point of production the day after the egg is laid.
eggs are not likely to absorb foreign odours.
gravity – 0.855 to 0.870 at 15oC
q Viscosity –
70 to 90 (should not be more than)
q Cotton seed, linseed and groundnut oil are
good sealing agents but mineral oils are preferable since they are less subject
to oxidative changes during storage.
The commercial egg treatment oils are
paraffin oil (Central Food Technology Research Institute)
q Myvacet 9-40 (developed at CFTRI – Mysore)
q Petroleum jelly
q Liquid paraffin
q Paraffin wax
q Coconut oil
q Carboxyl methyl cellulose
q Technical white oil.
q Intert gas usually N2:CO-94.6
q The eggs are placed in a plastic bags or
special plastic cartons which are filled with this gas to seal the pores
q But it is costly
q Disadvantage is transpiration is
difficulty and thus causes cloudiness of
4. THERMAL PROCESSING
q This method is good for fertile eggs, since
it kills embryos and therefore is also known as ‘defertilization’ method.
q This includes
Flash heat treatment
FLASH HEAT TREATMENT
q The eggs are immersed for 2 to 3 seconds
in water at 71°C.
q Advantage is that it destroys bacteria
present on the surface of shell besides coagulating a thin film of albumen
immediately beneath the shell membrane and thus seal the shell internally.
q The eggs are immersed in water at
49°C for 35 minutes or
54°C for 15 minutes or
56°C for 10 minutes or
60°C for 5 minutes in order to stabilize the thick albumen so that such
eggs retain fresh appearance much longer than unheated eggs
q Simultaneous oil coating and
thermo stabilization complement each other in
maintaining the internal quality of egg.
q Eggs for cold storage must be clean,
unbroken, free from fungus and other infections.
q A temperature of 0oC or 30-32oF
and relative humidity of 85-90% is recommended for cold storage of eggs to
preserve them for 5 to 8 months.
q For short period of preservation of 2 to
3 months, eggs can be stored at 10-12oC or 50-55oF with a
relative humidity of 60-70%.
q Intact eggs are held at the lowest
possible temperature that will avoid freezing and bursting of the shells.
q Yolk and while contents may be frozen separately
q The egg content frozen at 10oF
to30oF or below zero
q Stored for 12 months
q Defrosting the frozen egg containers carried
out in egg room at the temperature of 12.8oC or cold running water
q Defrosted eggs are used within few hours
q Its quality determined by
odour,apperance,SPC,sediment and functional tests
q Frozen eggs free from mouldy,sour or putrid odour
q It should have 25.5% of solid and SPC not
more than 20,000,000/ gram
This is another method of preserving egg contents or edible eggs. Egg products of commercial utility are
prepared by drying or freezing eggs.
Albumin flakes, yolk and egg white powder can be produced by drying
Frozen yolk or frozen egg white
can be produced by freezing.
Egg white powder production –
Albumin flakes – pan or cabinet
drying method is mostly adopted
q Finally preservation of quality of egg or egg
contents to maintain its flavour.
q Eggs are pick up flavour from the area.As
such storage area onion ,decaying veg material oil,gasoline or organic solvent
to be avoided.