by- Dr. Akash Thakor
The egg is a biological structure intended by nature for reproduction. It protects and provides a complete diet for the developing embryo, and serves as the principal source of food for the first few days of the chick’s life. The egg is also one of the most nutritious and versatile of human foods.
Composition
An average-sized egg weighs approximately 57 grams (about 2 ounces). Of this weight, the shell constitutes 11 percent; the white, 58 percent; and the yolk, 31 percent. Normally, these proportions do not vary appreciably for small or large eggs. The percentage composition of the edible portions is:
Percent
Water
Protein
Fat
Ash
Whole egg
74
13
11
1
White
88
11
..
..
Yolk
48
17
33
1
Essential nutrients
Eggs are especially valuable as a source of protein. In fact, egg protein is used as the standard against which the quality of other food proteins is measured. One egg contains about 6 to 7 grams of protein. People of all ages need adequate protein for building and repairing body tissues.
The fat in the yolk is so finely emulsified that it is digested easily, even by infants. The ratio of unsaturated to saturated fats is about 2 to 1. This is considered very desirable. Oleic acid is the main unsaturated fat. It has no effect on blood cholesterol.
Eggs contain vitamin A, the B vitamins (thiamin, riboflavin, and niacin), and vitamin D. All are necessary during childhood and adolescence for growth. Eggs also contain an abundant supply of minerals, such as iron and phosphorus, which are essential for building and maintaining strong, healthy bodies. But eggs are low in calcium (it is in the shell), and contain little or no vitamin C.
Individuals on weight-reducing programs find eggs beneficial. To lose weight, calorie intake must be reduced, while maintaining a well-balanced diet. An egg provides good nutrition and contains only about 80 calories.
Value of eggs
Food prices continue to climb, particularly for high-protein foods, and consumers are constantly searching for ways to reduce their food bill. One way is to include more eggs in the diet. Comparing protein foods on a pound-for-pound basis, eggs cost about 95 cents a pound when large eggs are selling for 64 cents a dozen. It is difficult to purchase any other high-protein food–meat or fish–for this low price.
Some standard dimensions of the average egg
Weight
58 gm
Volume
53 cm³
Specific Gravity
1.09
Long Axis
5.7 cm
Short Axis
4.2 cm
Long circumference
15.7 cm
Short circumference
13.5 cm
Surface Area
68 cm²
The shape may be described as oval. The normal egg weight range is 35 gms to 77 gms. The Proportions and solids contents of the components of the average egg are:
Shell
10.5 %
Yolk
31 %
White
58.5 %
Total Edible
89.5 %
