• Egg shell
Eggshell contains calcium carbonate, magnesium carbonate, Phosphorus pentoxide and organic matter (matrix protein & polysaccharide).
• Egg White
Egg white consists of water largely with no fat or carbohydrate but contain 8% to 12% protein. 20per cent to 25per cent of the total white of whole eggs is thin white. Different types of proteins are present in egg white –
Ovalbumin, Conalbumin, Ovamucoid, Ovomucin, Lysozyme, Avidin (anti-nutritional factor), Ovoglobulin, Ovoinhibitor.
• Egg Yolk
Egg Yolk comprises mostly 25% to 33% of fat and 15% to 17% protein and the remaining water. The yolk contains 50% of the solid portion.
a. Protein: It contains different Proteins like – Lipovitellins, Phosvitin, Livetin, Low – density lipoprotein.
b. Fat: It contains triglycerides, phospholipids and lipoproteins. Lipoproteins are complexed with phospholipids and cholesterol.
a. Shell – the colour giving substances in the egg-shell are ooporphyrins, derivative of hemoglobin give brown colour and oocyanin, a product of bile formation gives bluish-green colour to the shell.
b. Egg White – egg white contains small amounts of ovoflavin. The riboflavin in the egg white, the greener is the colour.
c. Egg Yolk – the colour of the egg yolk varies from a pale yellow to brilliant orange depending upon the amount and type of the pigment Carotenoids and xanthophylls and present in the diet of the hen.
• Proteins :
Egg contents 12% to 14% protein which are well balanced with respect to all the essential amino acids.
• Fat :
The egg is good sources of lecithin. It is the source of essential fatty acids, linoleic acid and arachidonic fatty acids.
• Minerals and Vitamins :
Important Vitamins – A, D, E, folic acid and B12 are present in the egg.
Important minerals such as Phosphorus, iron, zinc and other trace elements are present in the egg.
NUTRITIVE VALUE OF EGGS (Per 100 gram) :
• Protein (g) 13.3
• Fat (g) 13.3
• Calcium (mg) 60.0
Note :- Eggs are rich source of all nutrients except Vitamin C for ascorbic Acid.