Definiton of Eggs, Structure and its Preparation

EGG

             Egg is the reproductive body laid by many of the female animal. However we deal here only about eggs laid by poultry.

 

STRUCTURE OF EGG

 The structure of an egg can be divided into three sections.

            1) Egg Shell               2)  Egg White            3)  Egg Yolk

Egg Shell:

            Eggs are covered with a hard shell to keep intact the fluid of the egg.  Egg shell consists of calcium carbonate, Magnesium, Carbonate, and Calcium phosphate.  The egg shells contain tiny holes called bloom which allows moisture to escape and air to get inside.

            The colour of the shell of eggs will depend upon the breed of the hen.  As the egg gets elder, the egg looses its moisture and thereby makes the egg lighter.

Egg White:

            Egg white accounts for 67% of the liquid weight of the egg.  Egg white is made up of 2 parlo.  A thick white surrounds the yolk. A thinner, more liquid part is between the membrane and the thicker white. Albumin protein is the major component of the white.  It also contains sulphur.  The sulphur is clear and soluble when raw.  It is white and firm when coagulated.

The Yolk:

            The yolk is the unfertilized embryo in the egg.  Normally situated in the center of the egg.  Two thread like structures called “CHALAZAE” hold the egg yolk in place.  The yolk contains water (51%), fat (30%) and protein (15%) and also iron.

CRITERIA FOR SELECTION:

            Eggs are selected according to the size of and quality of the egg. Methods to be followed while judging the quality of eggs are:

I. CANDLING:

            It is a process in which one holds egg against the light to check the quality of egg yolk, white of egg, air cell and undesirable marks or cracks on the egg.

II. GRADING EGGS:

            The grading of eggs is based on a number of factors.  There are 3 grades of eggs: AA, A and B.  Age and handling of the egg are the primary determination of quality.  As an egg ages, the white becomes thin and the air cell between membrane and shell enlarges.  The yolk membrane becomes thinner as the egg ages.  This results in yolk which spreads more easily and breaks.

III.  BUOYANCY TEST:

            Place the eggs in water and observe the happenings:-

AA) An egg to newly laid is heavy. It sinks and lies flat on the bottom.

A)   As the egg ages, an air pocket expands and adds buoyancy. A week old egg begins to rise.

B)    As three week old egg stands upright as the air protect expands further

IV.  SPREAD TEST:

            Egg are braked to check the quality of white and yolk. 

AA) As the eggs are newly laid, whites are thick, spreads very little and yolk stands high.  The chalazae are prominent.

A) As the eggs are aged little, moderately spreads, chalazae are visible, yolk fairly stands high.

B) When broken, spreads greately, having only a small amount of thick white.  The yolk is flat and broad.  Chalaze are very small or completely absent.

EGG SIZES:

            Although eggs are graded for quality, this does not address the issue of size.  The grade of egg does not relate to the size of the egg.

            Eggs are classified as:

            JUMBO (70gms)

            EXTRA LARGE (60 – 65 gms)

            LARGE (55 – 60 gms)

            SMALL (50 – 55 gms)

            PEE WEF (45 gms)

MARKET FORMS:

            Eggs are currently available in a number of forms.  It is common for a large kitchen to have a variety of firms to suit the different purposes.  The common forms are:

1. FRESH /SHELL EGGS:  This is the preferred form for most breakfast cookery.  In many kitchens fresh eggs are used for all productions. 
2. FROZEN EGGS:  Frozen eggs are of high quality and available in number of forms.  They are pasteurized in number in processing, reducing concerns about bacterial growth, available as white eggs, whites, yolks. 
3. DRIED EGGS:  These are available as whole eggs, yolks or whites.  They are used primarily for baking.

METHODS OF COOKING:

            The preparation of eggs are classified under two heads:

            A)  With Shell                        B)  Without Shell

With Shell: [Boiled Eggs]

            Eggs are simmered and are not boiled. They are simmered for different timings to suit the guest needs:

            SOFT             3 – 4 minutes

            MEDIUM        5 – 7 minutes

            HARD            12 – 15 minutes

After the eggs are simmered they can be kept in cold water to avoid further cooking. Another disadvantage of boiling the eggs for a longer period, the whites will tend to become rubbery.

B. Without Shell:

            The egg can be cooked by breaking the egg shells.  Following are the different methods by which eggs are cooked:

a)  Poaching     b)  Scrambled      c)  Fried  d)  Omlette     e)  Basted     f)  Souffles

USES OF EGGS:

            Eggs are used extensively in todays kitchen.  The following are the uses of eggs:

• Raising Agent (E.g., Sponge cake)
• Binding Agent (E.g. Cutlets)
• Thickening Agent (E.g. Liaison)
• Emulsifying Agent (E.g. Mayonnaise sauce)
• Clarifying Agent (E.g. Consomme)
• Leavening  Agent (E.g. Meringue)
• Garnish (E.g.) Consomme Royale
• Coating (E.g. Breads)

STORAGE OF EGGS:

            Protection of egg is of great importance. Remember that eggs lose quality quickly at room temperature.  They should always be stored at 0° - 5°C.

            Eggs have porous shells, which allow air to enter the shell.  They should be stored away from foods that may pass on undesirable odors.