Bsc 1st Year Notes-Eggs

                                                   

                                                    EGGS-NOTES

                         

 

 Consume the eggs of birds like hen, goose, turkey, fowls etc. The eggs of only those birds whose meat is eaten are used for cooking purposes. But in India, eggs of hen and ducks are used. Eggs serve a versatile and basic function in diet and in food preparation. They are a pre-packaged container of nutrients in their own disposable shell.

Grading of eggs
(U.S. weight classes for eggs, minimum weight per dozen for each size)

Jumbo Extra large Large Medium Small Peewee
30 oz/
75 Gms/egg
(900 Gms per dozen) 27 oz/
68.5 Gms/egg
(810 Gms per dozen) 24 oz/
60 Gms/egg
(720 Gms per dozen) 21 oz/
52.5 Gms/egg
(630 Gms per dozen) 18 oz/
45 Gms/egg
(540 Gms per dozen) 15 oz/
37.5 Gms/egg
(450 Gms per dozen)
N.B.:1 oz=30 Gms approx.

Structure of eggs

                                    


Structure of an Egg

The egg is composed of shell, white and yolk. The egg white forms 2/3rd of the whole egg and the yolk forms 1/3rd.
1. Shell
It is the outer hard covering of the egg and is made up of Calcium, Magnesium carbonate and Calcium phosphate. The shell gives shape to the egg and holds the inner contents. The shell contains thousands of pores that allow CO2 and moisture to escape, as well as air to enter. The shell is covered by a cuticle membrane or Bloom and should not be washed. The bloom acts as protective covering blocking the pores, and prevents moisture loss and bacterial contamination. When eggs are washed before going to the market, the cuticle is removed. To protect the egg, the washed eggs are coated with a thin film of edible oil.
2. Membrane
Beneath the shell, there are two semi permeable membranes - the outer and the inner. These membranes act as a protective layer in case the shell cracks.
3. Air cell
On one side of the egg (broader), both these membranes separate to form an air cell. This is formed by contraction of the contents as soon as the egg is laid, due to the difference in the outside temperature.
4. Egg white
It has 1/8th part of the protein, which is called albumin; the remaining being water. The egg white consists of three parts – the outer thin albumen, the middle thick albumin and the inner thin albumin.
5. Egg yolk
The yolk is separated from the white by a membrane called vitelline membrane. This membrane prevents the mix of both yolk and white. 1/6th parts of the egg yolk contains proteins, 1/3rd fat and the rest water, Vitamins and minerals like Calcium, Phosphorus, Iron etc.
6. Chalaza
The egg is kept in position at the centre of the egg with the help of the chalaza. It has a thick-cord like appearance and is composed of proteins. This chord-like structure may have to be strained while making custards.


                                         eggs are coated with a thin film of edible oil.
2. Membrane
Beneath the shell, there are two semi permeable membranes - the outer and the inner. These membranes act as a protective layer in case the shell cracks.
3. Air cell
On one side of the egg (broader), both these membranes separate to form an air cell. This is formed by contraction of the contents as soon as the egg is laid, due to the difference in the outside temperature.
4. Egg white
It has 1/8th part of the protein, which is called albumin; the remaining being water. The egg white consists of three parts – the outer thin albumen, the middle thick albumin and the inner thin albumin.
5. Egg yolk
The yolk is separated from the white by a membrane called vitelline membrane. This membrane prevents the mix of both yolk and white. 1/6th parts of the egg yolk contains proteins, 1/3rd fat and the rest water, Vitamins and minerals like Calcium, Phosphorus, Iron etc.
6. Chalaza
The egg is kept in position at the centre of the egg with the help of the chalaza. It has a thick-cord like appearance and is composed of proteins. This chord-like structure may have to be strained while making custards.



                              USES OF EGGS IN COOKERY

Eggs are extremely useful food as they are used in making so many different kinds of dishes, either as a full menu or breakfast dishes.
Eggs are an integral part of cookery and they can be used for many purposes including:

1. Binding

The stickiness of the egg helps to attach crumbs or items to food and binds the ingredients together. Examples: you can add an egg yolk to burgers or fish cakes, it will help them to stick together. An egg batter provides a binder for added coating, frequently an outer coating of flour, bread, crumbs or batter is added to food such as meatloaf to enhance its appearance, texture or flavor

2. Coating

Beaten eggs can be used to coat fish or chicken portion before they are dipped into breadcrumbs and fried. This gives a crisp and attractive finish

3. Glazing

If pastry and scones are brushed with beaten egg and milk, they will have a shinny golden brown appearance when cooked
 

4. Emulsifying Agents

Eggs are used to form stable emulsion when you add an egg or egg yolk to mayonnaise, it helps the oil and vinegar to stay smoothly blend together. Eggs are also used as emulsifiers in ice creams, cakes and cream puffs

5. Clarifying

Raw eggs maybe added to hot broths. Egg whites will hold impurities and bring them to the top of a simmering liquid.  

6. Enriching other foods

Egg provides extra flavor and body in sauces and sweets. You can add a beaten egg to mashed potatoes or a milk pudding to improve the food value and make the dish more nutritious.

7. Aerating or Whisking

Eggs will hold a lot of air when whisked. Eggs will hold the air in small bubbles “to tighten” mixtures by encapsulating air bubbles. You will observe this when making a sponge cake, Pavlova or meringues. All the air held in the mixture by the egg makes the cake light and well risen.