PRESERVATION q Egg is aperishable product having short shelf life. q Preservationof eggs should start from the point of production itself.q Collectionof eggs at least 3 times daily.
q Using aclean receptacle with ventilated sides and bottom, preferably filler flats.q Carefulhandling of eggs during collection and while storing in filler flats etc.,q Cooling the eggs quickly to 50oF or lessat 75-85% relative humidity.q Marketing the eggs at least twice weekly.
FOLLOWING CHANGES OCCUR ON STORAGE : 1.Moisture loss through the pores 2.Gaseous (CO2) loss 3.Change of PH 4.Movement of water from thick albumen to other albumen layers and to yolk 5.
Entry of microbes through the pores 6.Embryonic development 7.Absorption of foreign odours THERE ARE TWO TYPE EGG PRESERVATIONA. ShelleggsB.
Liquideggs A.SHELL EGGSPRINCIPLEq Retarding the microbial growth andsealing the pores of the shell to minimize the evaporation of moisture andescape of gases, thus reducing the physico-chemical changes in the egg. q Sometimes, a combination of methods isemployed for effective preservation.METHODS: 1.Immeresion in liquid a) Lime water b) Water glass method 2. Oil coating 3.Gas 4.
Thermal processing 5.Cold storage 1.IMMERESIONIN LIQUID A) LIME WATER1litre 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. q To allow the solution to settled down andfilter with muslin clothq The eggs are immersed in this clear fluidfor 16 to 18 hours, and then taken out.q Eggs are dried at room temperature andtransferred to filter flats. The eggs can then be stored for 3 to 4 weeks atroom temperature B) WATERGLASS METHODq Water-glass-10 % sodium silicate q The eggs are left immersed overnight inwater-glass.
q It deposits a thin precipitate of silica onthe surface of egg shell, possesses intrinsic antiseptic properties and doesnot impart odour or taste to the eggs. 2. OIL COATINGq Oiltreating egg with a white, odourless, paraffin base mineral oil used.q Sealingthe pores with oil .
q Therate of CO2 escape is considerably reduced and evaporation of water ,loss of egg weightalso reduced.q Oil treated eggs are kept in cold room.q If oil treatment is to be effective it shouldbe done preferably at the point of production the day after the egg is laid.
q Theseeggs are not likely to absorb foreign odours. q Specificgravity – 0.855 to 0.870 at 15oCq Viscosity – 70 to 90 (should not be more than) q Cotton seed, linseed and groundnut oil aregood sealing agents but mineral oils are preferable since they are less subjectto oxidative changes during storage.The commercial egg treatment oils areq Heavyparaffin oil (Central Food Technology Research Institute)q Myvacet 9-40 (developed at CFTRI – Mysore)q Myvacet 5q Myvacet 7q Petroleum jellyq Liquid paraffinq Paraffin waxq Coconut oil q Dalda q Carboxyl methyl celluloseq Technical white oil.
3.GASq Intert gas usually N2:CO-94.6 q The eggs are placed in a plastic bags orspecial plastic cartons which are filled with this gas to seal the pores q But it is costlyq Disadvantage is transpiration isdifficulty and thus causes cloudiness ofalbumin 4. THERMAL PROCESSINGq This method is good for fertile eggs, sinceit kills embryos and therefore is also known as ‘defertilization’ method.
q This includes i. Flash heat treatment ii. Thermostabilization iii. Simultaneouscoating.
FLASH HEAT TREATMENT q The eggs are immersed for 2 to 3 secondsin water at 71°C. q Advantage is that it destroys bacteriapresent on the surface of shell besides coagulating a thin film of albumenimmediately beneath the shell membrane and thus seal the shell internally. THERMOSTABILIZATION 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 sucheggs retain fresh appearance much longer than unheated eggsq Simultaneous oil coating andthermo stabilization complement each other inmaintaining the internal quality of egg. 5.COLD STORAGEq Eggs for cold storage must be clean,unbroken, free from fungus and other infections.q A temperature of 0oC or 30-32oFand relative humidity of 85-90% is recommended for cold storage of eggs topreserve them for 5 to 8 months.
q For short period of preservation of 2 to3 months, eggs can be stored at 10-12oC or 50-55oF with arelative humidity of 60-70%. q Intact eggs are held at the lowestpossible temperature that will avoid freezing and bursting of the shells. FREEZINGq Yolk and while contents may be frozen separatelyq The egg content frozen at 10oFto30oF or below zeroq Stored for 12 months q Defrosting the frozen egg containers carriedout in egg room at the temperature of 12.8oC or cold running waterq Defrosted eggs are used within few hours q Its quality determined byodour,apperance,SPC,sediment and functional testsq Frozen eggs free from mouldy,sour or putrid odour q It should have 25.5% of solid and SPC notmore than 20,000,000/ gram B.LIQUIDEGGSDRIED EGGS This is another method of preserving egg contents or edible eggs. Egg products of commercial utility areprepared by drying or freezing eggs.
Albumin flakes, yolk and egg white powder can be produced by dryingprocess. FROZEN EGGS Frozen yolk or frozen egg whitecan be produced by freezing. Egg white powder production -spray drying Albumin flakes – pan or cabinetdrying method is mostly adopted q Finally preservation of quality of egg or eggcontents to maintain its flavour.
q Eggs are pick up flavour from the area.Assuch storage area onion ,decaying veg material oil,gasoline or organic solventto be avoided. REFERENCES Indian chicken.com