Eggs are one of the most nutritious and versatile foods in the kitchen, they can be served on their own or used as an ingredient in many dishes starting from soup to desserts. It provides texture, structure, flavour and moisture as well as the nutrition. Eggs can be brown or white; colour has no effect on quality or flavour but depends on the breed of the hen.
The nutritional value of eggs varies with their size; it is not an important factor in judging their quality. Larger eggs, of course, have more food value than small ones. A single large egg provides
6.5gm of protein or about 13% of the recommended daily intake for adults, as well as 80 calories and a good amount of iron, phosphorus, thiamine, and vitamins like A, D, E, and K. The disadvantage of the egg as a staple diet is their high cholesterol content. The yolk of an egg is about 50% water,34%lipids, fats, and related substances, and 16% protein with traces of glucose and minerals. The egg is made up of approximately 11% shell and 89% interior. The composition of the shell is important from the viewpoint of food safety, sanitation, and aesthetics. It contains calcium, carbonate (94%), magnesium carbonate (1%), calcium phosphate (1%), and 4% organic matter. It is important to recognize that there has been considerable information that the hen’s diet can impact the composition of the egg.
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.
- 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 a 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.
- 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.
- Aircell: One side of the egg is broader than the other, the reason being both these membranes separate to form an air cell. This is formed by the contraction of the contents as soon as the egg is laid, due to the difference in the outside temperature.
- 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.
- Egg yolk: The yolk is separated from the white by a membrane called the vitelline membrane. This membrane prevents the mix of both yolk and white. 1/6th of parts of the egg yolk contains proteins, 1/3rd fat and the rest water, Vitamins and minerals like Calcium, Phosphorus, Iron, etc.
- Chalaza: The egg is kept in position at the center of the egg with the help of the chalaza. It has a thick-cord like an appearance and is composed of proteins. This chord-like structure may have to be strained while making custards.
Composition of hen’s egg.
Parts of Egg
The grading of quality, which is not mandatory by law, is independent of the different sizes available.
Shell: clean; unbroken, practically normal
Air cell: 1/8 inch or less in depth; practically regular
White: clear, firm, “upright”
Yolk: well centered; outline slightly defined; free from defects
Shell: clean; unbroken, practically normal
Air cell: 2/8 inch or less in-depth; practically regular
White: clear, maybe reasonably firm
Yolk: may be fairly well centered; outline fairly well defined; practically free from defects
Shell: clean to slightly stained; unbroken, maybe slightly abnormal
Air cell: 3/8 inch or less in-depth, maybe free but not bubbly
White: clear, maybe slightly weak
Yolk: may be off-center, outline well defined, maybe slightly enlarged and fattened, and may show definite but not serious defects
Shell: Clean to moderately stained, unbroken, may be abnormal.
Air cell: maybe over 3/8 inch in depth, maybe free or bubbly
White: may be weak and watery, small blood clots or spots may be present
Yolk: may be off center, enlarged and flattened, may show clearly the germ development but no blood; may show other serious defects; outline may be plainly visible.
In any case, slow deterioration in quality goes as long as eggs are stored, SO PROMT USE IS THE BEST USE.
The best grade (AA) has a firm yolk and white that stand up high when broken onto a flat surface and do not spread over a large area. In the shell, the yolk is well centered, and the air sac is small. As eggs age, they lose density. The thin part of the white becomes larger, and the egg spreads over a larger area when broken. Also, the air sac becomes larger as the egg loses moisture through the shell.
- Most used eggs in commercial and home cookery are Large Eggs.
- Jumbo and Extra-Large eggs are sometimes used as Breakfast eggs for poaching and frying
- Medium, Small, and Pee Wee eggs are rarely used.
Storage of eggs
Eggs should be stored in the refrigerator in their cartoon to maintain maximum freshness and to avoid absorbing other food odors through their porous shells.
- Cool place 0-5 C (32-41 F)
- Away from possible contaminants such as raw meat.
- First in first out
- Hands should be washed before and after handling
Types of Eggs used
Hen, Turkey, Guinea fowls, Ducks, Geese
Market forms Of Eggs
- Fresh eggs: – Often used for Breakfast cookery
- Frozen Eggs: – Includes whole egg, whites, yolks, whole egg with extra yolk, etc. It should be pasteurized before freezing. It is used for scrambled eggs, omelets, French toasts, and baking.
- Dried eggs: – Should be pasteurized before drying. Includes whole egg whites & yolks. Moisture is removed through evaporation. They are primarily used for baking.
GENERAL COOKING PRINCIPLES
The most important rule of egg cookery is simple: Avoid high temperatures and long cooking times. In other words, do not overcook. This should be a familiar rule by now. Overcooking produces tough eggs, causes discoloration, and affects flavour.
Eggs are largely protein, so the principle of coagulation is important to consider.
Eggs coagulate at the following temperatures:
Whole eggs, beaten about 156°F (69°C)
Whites 140° to 149°F (60° to 65°C)
Yolks 144° to 158°F (62° to 70°C)
Custard (whole eggs plus liquid) 175° to 185°F (79° to 85°C)
Note: That whites coagulate or cook before yolks do. Therefore it is possible to cook eggs with firm whites but soft yolks. Note also that when eggs are mixed with a liquid, they become firm at a higher temperature. However, 185°F (85°C) is still much lower than the temperature of a sauté pan or skillet over high heat. As the temperature of coagulation is reached, the eggs change from semiliquid to solid, and they become opaque. If their temperature continues to rise, they become even firmer. An overcooked egg is tough and rubbery. Low temperatures produce the best-cooked eggs. If egg-liquid mixtures such as custards and scrambled eggs are overcooked, the egg solids separate from the liquids or curdle (Syneresis). This is often seen as tough, watery scrambled eggs.
Sulphur: The familiar green ring you often see in hard-cooked eggs is caused by cooking at high temperatures or cooking too long. The same green colour appears in scrambled eggs that are overcooked or held too long on the steam table. This ring results when the sulphur in the egg whites reacts with the iron in the yolk to form iron sulphide, a compound that has a green colour and a strong odour and flavour. The best way to avoid green eggs is to use low temperatures and short cooking and holding times.
Foams: Beaten egg whites are used to give lightness and rising power to soufflés, puffy omelettes, cakes, some pancakes and waffles, and other products. The following guidelines will help you handle beaten egg whites properly.
- Fat inhibits foaming: When separating eggs, be careful not to get any yolk in the whites. Yolks contain fats. Use very clean equipment when beating whites.
- Mild acids help to foam: A small amount of lemon juice or cream of tartar gives more volume and stability to beaten egg whites. Use about 2 teaspoons cream of tartar per pound of egg whites (20 mL per kg).
- Egg whites foam better at room temperature: Remove them from the cooler 1 hour before beating.
- Do not overbeat: Beaten egg whites should look moist and shiny. Overbeaten eggs look dry and curdled and have lost much of their ability to raise soufflés and cakes.
- Sugar makes foams more stable: When making sweet, puffed omelettes and dessert soufflés, add some of the sugar to the partially beaten whites and continue to beat to proper stiffness. (This will take longer than when no sugar is added.) The soufflé will be more stable before and after baking.
USES OF EGG IN COOKERY
BINDING AND COATING
Egg used in such food mixtures as meatloaf or croquettes is distributed through the mixture. Upon heating, the proteins coagulate, binding the food into a cohesive mass of the desired form. Therefore croquettes, for example, retain their shape during the cooking process. Frequently an outer coating of flour, breadcrumbs, cereal, or butter is added to food to enhance its appearance, texture, or flavour. An egg batter provides a binder for added coatings.
Foam is created when the egg white is beaten. The foam is made of bubbles surrounded by a thin, elastic film of egg white. When the foam is incorporated into a mixture, it provides leavening for such products as omelettes, soufflés, sponge cakes, and meringues. When these products are heated the air bubbles expand and the egg white film hardens. The volume of egg yolks makes its foaming power considerably lower than that of the egg white.
EGG WHITE FOAM
Egg white foams are used in many foods to make them light and porous. Egg white foam is a colloid of bubbles of air surrounded by part of the albumen that has been denatured by the beating of egg white. The denatured albumen is stiff and gives stability to the foam. An egg white is beaten, it loses its elasticity but some elasticity is necessary for an egg white foam used in such dishes as soufflés and cakes so that the air cells can expand without breaking down the cell walls. This expansion occurs in the heated oven before the albumen becomes rigid.
Soft meringues are made with 2 tbsp of sugar for each egg white. Topping the fillings while they are still hot and baking the pie at 375 F (190 C) until the meringues reach a light colour yield a stable meringue and reduce the amount of liquid (called leakage) collecting under the meringue and the tendency to the meringue to slip from the surface of the pie. Hard meringues have a much higher proportion of sugar to the egg white. As much as 1/4 cup of sugar per egg white may be used. Since sugar retards the denaturalization of the egg proteins, a longer whipping time is necessary. Hard meringue can be shaped into such subjects such as baskets, hearts, pie, shells, or animal figures. The baking temperature is very long (1 1/2 hrs) and very low (275 F or 135 C).
Eggs are used to form stable emulsions, mayonnaise for example Oil and Vinegar separate out unless the oil droplets are coated with the substance that keeps them from running together. Egg yolk is often effective in accomplishing this. Eggs are used as emulsifiers (Lecithin) in ice cream, cakes, and cream puffs.
Beaten egg whites will act as an interfering substance in mixtures to be frozen, such as “sherbet “. Tiny bubbles of air trapped in air prevent ice crystals from coming together and creating large masses of icy material. Egg whites and at times, egg yolk perform a similar service in the making of candy, an egg white added to certain candies interferes with the formation of large sugar crystals.
Raw eggs may be added to hot broths and coffee. When the proteins in the egg coagulate, they trap the loose particles in the liquid and clarify it. Custard, Puddings, and Pie Fillings: custard may be cooked over hot water and stirred as it is cooked (soft custard) or maybe cooked without stirring (baked custard). The coagulation of soft custard takes place at about 160 F (70 C). If in making a soft custard the mixture is held at the coagulation point for too long or if the temperature exceeds this level the protein is over-cooked, the mixture thickens unevenly, and the finished product will be curdled. Baked custard is cooked without stirring in an oven at 350 F (176 C).
How to separate eggs?
The best way to separate the white and yolk is by using the eggshell. Avoid breaking the egg into one hand and allow the white to run through the finger. The white can absorb grease and odours which will inhibit its beating qualities.
- Have two bowls ready. Crack the egg as close to its center as possible by hitting the shell firmly against the edge of a bowl or the sharp edge of a counter. Using your thumbs, pull shells apart, allowing some of the white to fall into the bowl.
- Pour yolk from the shell to shell, allowing white to dribble into the bowl. Use one side of the shell to detach the remaining white from the yolk. Use a shell half to remove. Any bits of yolk which might slip into the bowl.
- Place yolk gently into the second bowl.
Whisking egg white
Whisking egg whites are the basis of making meringues and are used to lighten the soufflés and mousses.
- Utensils should be large enough to allow for a full increase in the volume of foam. However, it should not be too large that the beater has no contact with egg whites.
- A rotary beater or wire whip should be used. The thinner the blade or finer the whip, the smaller are the air cells and the finer is the foam.
- Egg white whips rapidly at room temperature.
- The whites must be free from any traces of yolks, oil from hands or bowl, and even water.
- Use a copper or stainless-steel bowl as glass and ceramic bowl seems to repel the whites and separate them.
- Rinse the bowl with vinegar or lemon juice to remove any impurities.
- Salt and cream of tartar are used in egg white. Salt is used for flavor. Lemon juice or cream of tartar makes the foam more stable.
- Sugar stabilizes the foam and prevents them from becoming grainy but must be added after the whites are stiff.
- The addition of water up to 40% of the volume of egg increases the volume of foam. It is incorporated towards the end of beating.
Whisking egg yolk
Egg yolks are often whisked separately with or without sugar, sometimes over the heat. The whisking increases the volume and lightens sauces as Hollandaise or adds air for cakes and batter.
Folding egg whites
It is a method of combining a light mixture and a heavier one without deflating the lighter one. To lighten the heavier or base mixture, add about a quarter of the beaten whites and stir them in thoroughly through the cut and fold method. Then spoon in the remaining whites and gently folds in by using a rubber spatula.
METHODS OF COOKING EGGS
Boiling and shelling hard and medium boiled egg (Oeufs Bouillis):
To make a boiled egg there are only two things to be kept in mind—one is the cooking time, which will be determined by the consistency of the white and yolk. The second is the water temperature. The egg should be plunged into the simmering liquid, boil and simmer for the required time. Commence timing once the water has reboiled.
The stages of boiling are:
- Soft Boiled (in the shell): Oeuf a la Coque – boiling time 3 to 4 minutes.
- Soft Boiled (without shell): Oeuf Mollet – boiling time 5 minutes.
- Hard-Boiled: Oeuf Dur – boiling time 8 to 10 minutes served with or without the shell.
- The occasional difficulty encountered when peeling the egg, which is because of the PH of egg white and so by the egg’s freshness. If the PH is below 8.9 – in a fresh egg it is closer to 8.0- then the inner membrane tends to adhere to the albumen, whereas when the PH is 9.2 after three days of refrigeration, the problem no longer exists.
- The other odd things about the hardboiled egg are the occasional appearance of a greenish-gray discoloration on the surface of the yolk. The color is caused by a harmless compound of iron and sulphur called ferrous sulphide, which is formed only when it’s heated.
- For shelling, crack the egg around its center, as for separation of the egg. Gently roll the egg on a work surface until the eggshell is cracked all around the center. Remove the shells away from the white.
- Store peeled egg in salted water.
SCRAMBLED EGGS (Ouefs Broilles)
In France, good, scrambled eggs are considered an art; gently stirred over low heat to a thick creamy puree which is elegantly garnished with truffles, smoked salmon, or chopped chives. These are prepared by thoroughly mixing the eggs, seasoning with salt and pepper, adding them to a little butter melted in a thick bottomed pan, then cooking slowly stirring with a wooden spoon until set. They may be finished with butter or cream. To hold scrambled eggs on a buffet, add one tablespoon of water, milk, or cream to one egg (one cup of 16 eggs). They are then cooked to a soft stage and then hold between 54 and 60 C ( 130- 140 F). 54 C (130 f) is the lowest temperature one can use without encouraging bacteria growth. Slightly overheating will cause the liquid to squeeze out and forms a separate puddle. It can be recognized when the liquid collects around the edge of; for example, custard or a mold of gelatine products and is termed as SYNERESIS (weeping).
POACHED EGGS (Oeufs Poches)
To poach eggs, fill a deep pan with about two and a half inches of water. Add one tablespoon of salt and one tablespoon of vinegar per gallon of water. The vinegar, an acid, helps to set the egg white and prevents it from spreading. Acid also makes the eggs more tender, whites whiter. The poached egg must be fresh, or it will spread even though vinegar is used. Both salt and vinegar help to coagulate the egg as soon as it enters the poaching liquid so that it retains a better shape.
Poaching egg in Bain-Marie (Oeufs Moules )
A cooking vessel with a lid is half-filled with water to form a bain-marie. Bring the water to boiling point. Prepare the egg molds with seasonings and a knob of butter to flavour and to prevent eggs from sticking to molds. Break the egg in individual molds and place in the bain-marie with the lid on for gentle cooking. Cook for 3-5 minutes so that white sets and the yolk remains soft. Turn out and serve hot.
Eggs are coddled in the shell. They are cooked by pouring boiling water over the edges, one pint of boiling water over an egg. The eggs are then covered and held in a warm place until cooked (six to ten minutes) for firm yokes and pleasantly soft whites.
EN COCOTTE (Oeufs en Cocotte)
Like poaching except that eggs are poached in porcelain dishes(cocotte). The dishes are buttered, the eggs placed in them and both placed in Bain Marie for about 2 to 3 min. This dish is served for lunch or dinner and is presented in and eaten from the cocotte dish in which it is cooked.
FRIED EGG (Oeufs Frits)
Indicates eggs gently cooked with oil/bacon fat/lard in a shallow frying vessel until white is firm while yolk remains soft. Fried eggs are often served with crispy fried bacon or sausages. The fried egg is the centrepiece of the great British breakfast, surrounded by bacon, sausage, tomatoes, mushrooms, baked beans, black pudding, and toasted bread. The ideal temperature range for fried egg is 255 0c to 2800f. Eggs done or cooked only on one side is known as SUNNY SIDE UP. For OVER EASY use a palate knife to flip each egg carefully.
Making omelettes is a very simple operation but to achieve great success a high degree of skill is required. Usually, 2-3 eggs are used per portion with proper garnishes or flavourings, which may be added in the following ways:
- Combined with egg before cooking.
- Placed into center of omelette before it is folded.
- Placed on top of the omelette, in a cavity after folding is complete.
Types of Omelets
- Plain Omelette: is prepared plain only with seasonings.
- Flat Omelette: Add garnish to the egg before making the omelette, turn out without folding, coloured side uppermost. Spanish TORTILLAS and Italian FRITTATAS are examples of this open-faced pancake-style omelette.
- Stuffed and folded Omelette: Place fillings in the center of omelette before folding.
- Folded and stuffed: Slit the turned out omelette along the centre of top surface,place in the fillings.
- Folded Omelette: Add garnish to the egg before cooking and then folded after making it.
- A well-seasoned heavy bottom iron or a steel pan is required. For seasoning pan to get a non-stick effect, add plenty of salt and heat it over moderate heat. Remove salt and wipe it with a dry cloth. Pour oil into the pan and heat steadily over a period until the pan is smooth. Remove excess oil and use it for making omelets.
- Never wash the pan, always wipe it with a dry kitchen cloth. Apply a film of oil and store.
- The texture of the omelette should be soft, with a firm exterior and a moist center. This is termed as BAVEUSE Omelets are generally cooked to order. Making Omelettes are like scrambled eggs except that they form a solid sheet or coagulated eggs, which are molded and often filled with herbs, jams, mushrooms, ham, cheese, and many other ingredients. French omelets with a sweet filling may be dusted with icing sugar and burnt lightly with a hot metal rod. Marks are left like grid marks on broiled steak. When new, omelette pans, like new pans and griddles, are seasoned in the manner described for pans, then never washed again (see fried eggs ) . Beating the yolks and the whites separately to stiff foam makes a puffy or soufflé omelette. It is started as a regular but finished in the oven at 163 C (325 F).
Soufflés are like puffy or foamy omelettes except that they have been thickened with flour, butter, and milk. The proportion of an egg is lower than in an omelette. To make a soufflé the eggs are separated and added to the white sauce or starch thickened mixture. The whites are beaten to soft foam before being folded into the rest of the materials. Soufflés are baked at 149 C (300 F) and they should be Served soon after they are cooked.
True custards contain only milk, eggs, sugar, and flavouring. No starch agent is added. Baked custards must contain enough eggs to produce a firm mass. Custards should be cooked in a container of water to prevent overheating. For firm custard heat the milk to about 66 C (150 F) then adds this to the mixture of sugar, eggs, and flavouring. An oven temperature of about 177 C (350 F) is used for baking custards, but if the temperature of the custard itself exceeds 85 C (185 F) the custard is likely to contain holes, be watery, and have a concave top. Once the custard is cooked it should be placed in a cool spot for setting in a pan of cold water. At a very high temperature synergetic occurs this is a separation of liquid from the gel, caused by contraction of the proteins.
PUDDINGS AND CREAMS
A thickened mixture of cornflour, milk, sugar, and flavouring is called a blancmange or cornflour pudding. If eggs are added to this mixture, the pudding is called a cream pudding. Bavarian Creams (Bavarois): Are cornflour or cream puddings made by light gelatine, whipped cream, beaten eggs, and other ingredients for Bavarian creams.1/4 tsp creams of tartar is added for each 5 egg whites. Zabaglione or Sabayon: is a dessert of Italian origin made with egg yolks, sugar, and wine (Marsala).
Are custards baked in a pastry case. It contains eggs, milk, cheese, bacon, and onions.