Eggs PDF - Characteristics, Structure, Deterioration & Uses

EGGS CHARACTERISTICS OF A FRESH EGG : The colour of the shell of an egg, either white or brown, depends on the breed of the hen producing it. The delicate velvety appearance on the shell of a fresh egg is known as bloom because of the protective mucous coating which the shell has when the...

EGGS CHARACTERISTICS OF A FRESH EGG : The colour of the shell of an egg, either white or brown, depends on the breed of the hen producing it. The delicate velvety appearance on the shell of a fresh egg is known as bloom because of the protective mucous coating which the shell has when the egg is laid. The inner air cell of a fresh egg is small. The content when broken out from the shell show an upstanding, well rounded yolk covered with a clinging layer of thick egg white, which in turn is surrounded by a relatively smaller amount of thin egg white. The colour of the yolk varies from golden to light yellow depending upon the amount of caratenoid pigments contained in it, and the white is practically colourless or slightly opalescent. There is no odour other than the characteristics of eggs, and when cooked the flavour will be excellent. STRUCTURE OF AN EGG : DETERIORATION OF EGGS : Changes begins as soon as the egg is laid, and thus it should be stored under suitable storage conditions. As shown in the shell : The mucous protective covering of the shell soon disappears leaving the shell shiny and more porous, thus enabling the carbon dioxide and moisture to pass more easily through it from the egg contents. This causes a loss in weight of the egg, a contraction of egg contents, and a resulting enlargement of the air space between the two membranous linings of the shell. As shown in the egg white : The loss of carbon dioxide through the shell is actually the reason for the increase in the alkalinity of an aging egg. As the deterioration progresses, the thick white gradually loses its firm jelly like consistency and decreases in volume, while the volume of thin egg white increases. These changes continue until the entire white portion becomes watery and drains away from the yolk when the egg is broken out of the shell.  As shown in the egg yolk : The consistency of the yolk becomes thinner on aging and enlarges as the water passes into it from the white through the enveloping vitellin membrane. As a result the increasing volume of the yolk stretches the surrounding membrane and weakens it so that, in the broken out egg, the yolk is no longer upstanding and well rounded, but instead becomes wide and flat. With continuous aging, the membrane which encloses the yolk may become so weakened that it breaks when the egg is opened, and as a consequence the white and the yolk cannot be separated from each other. OFF ODOURS : Due to the chemical reactions in the egg components during aging, it imparts characteristic and familiar off odours and flavours. If this continues long enough, such eggs become inedible. Generally the fowl smelling, gaseous substance formed from these reactions is hydrogen sulphide. During the process of making hard boiled eggs, when the eggs are heated for some time in the shell, the hydrogen sulphide gas formed chiefly in egg white, passes through the vitellin membrane and reacts with iron compounds in outer yolk areas to form ferrous sulphide which can be seen as a black film like deposit, called the black ring, enveloping the yellow hard boiled yolk. The film can be avoided in a fresh egg but if it is subsequently aged, care has to be taken while boiling as for prolonged cooking or cooking too much in advance will have the effect of the black ring. It is essential that boiled eggs used for stuffing, garnishing, etc should be cooled quickly after boiling. ACTION OF HEAT / COAGULATION : The action of heat on proteins accounts on the principle changes that occur when eggs are cooked. Both white and yolk coagulates and the rate of coagulation and the firmness of the gel will depend on  Length of heating period and intensity of heat  The presence of added material such as water, milk, sugar and salt. Ingredient Coagulation Temperatures Gel Temperature Whole egg 57°C - 66°C (135°F - 150°F) 70°C – 74°C (158°F – 165°C) Egg white 58°C - 62°C (136°F - 144°F) 62°C – 70°C (144°F – 158°C) The higher the cooking temperature, the more rapid the coagulation and firmer the gel. The changes even takes place at a lower temperature below the boiling point, by a longer heating period, and the egg is superior in nutritive value as well as in flavour, to an egg cooked at a higher temperature for a shorter period. USES OF EGG : 1) As a leavening agent by making the dish light by foam formation to make the dish light – as in soufflés or meringues. 2) As a binding agent as in croquettes. 3) As a nutritive agent as egg is rich in proteins, Vitamin A, D and also small amount of Vitamin B complex, minerals and essential fatty acids. 4) To decorate and garnish dishes.  5) As a thickening in custards and salad dressings. 6) For emulsification as in mayonnaise sauce. 7) As a coating as in fried food. 8) To enrich a mixture as in rich cakes. 9) As a main dish for breakfast. 10) As a nourishing and an easily digestible food for invalids and infants. POPULAR BREAKFAST EGG PREPARATION : a. Boiled Egg : This preparation is the most simple preparation where the whole egg is completely immersed in boiling water and cooked till the egg coagulates, forming a complete hard mass from the liquid state. The eggs are carefully lowered with a metal spoon without cracking the shell in enough water to cover the eggs. a. Hard Boiled Egg : For a portion of egg, it generally takes 8 – 10 minutes and both the egg white and the egg yolk hardens completely. b. Soft Boiled Egg / Boiled Egg to order : Cooked as per the request of the guest, i.e. 4 minutes, or 5 minutes or so on. In these cases the egg is not completely coagulated and is in a semi solid state. b. Poached Egg : In this preparation the egg is broken in simmering water in which vinegar and salt has already been added. The egg white coagulates faster in an acidic medium which is assisted by the presence of vinegar. The egg white solidifies completely but the egg yold still remains in a soft, with a thin white coating on top. Care should be taken that it should not be cooked for longer time or else the yolk will harden completely. c. Fried Egg : Another very popular egg preparation where the eggs are broken on a hot plate or pan carefully without breaking the yolk and fried lightly with limited quantity of oil. The texture will be very similar to poached egg, where the egg white will harden more in comparison to the egg yolk. a. Sunny Side Up / Bulls Eye : In this style the two yolks appear brightly on top with a clear distinctive colour. The eggs are cooked for a minimum time till they are just ready to be taken out of the pan. b. Over easy : In this style an extra step is taken after the sunny side is done. The ready eggs are flashed under the salamander to give a very light colour on top of the egg yolks, still keeping the yolks soft. c. Well done : In this style the fried egg is fried on both sides and thus the yolk hardens along with the egg white. d. Omelette : In this preparation the egg white and yolk is beaten thoroughly together with a whisk to incorporate air so that the omelette is light and fluffy. This mixture is then placed on an omelette  pan and fried till the mixture starts to coagulate. It should be noted that while preparing an omelette, the texture should be hard from outside but soft inside. a. Plain Omelette : In this style the round coagulated egg is book folded or folded in a cresent shape and served. b. Stuffed Omelette : There can be numerous options of omelettes with stuffings. Few popular stuffed omelettes are Cheese Omelette, Chicken Omelette, Mushroom Omlete, Ham Omelette, Masala Omelette. c. Spanish Omelette : A Spanish delicacy and the only omelette which is open faced, i.e. not folded. The egg mixture is cooked on a pan and boiled diced potatoes and peppers are sprinkled on the top. The omelette is then flashed in a salamander or oven so that it puffs up in volume. It is then served immediately. e. Scrambled Egg : Another popular egg preparation where the egg is beaten with cream / milk, butter and seasoning. This mixture is slowly cooked in butter till it forms small granular structure and a creamy mixture. It should be ensured that the texture is well maintained and the scrambled egg does not turn watery on the plate. It is also for this reason that a scrambled egg is served on toast, so as to absorb the extra moisture in the egg. Note : 1) Never use black peppercorn powder in egg preparations if required at any point. It is rather advisable to eliminate pepper powder as many guests may be allergic to pepper and it also spoils the presentation effect. 2) The number of eggs served in one portion is 2 pieces unless otherwise requested by the guest. 3) Eggs are considered as a main course in breakfast service. 4) Eggs are served with an accompaniment of hash brown potatoes and grilled tomatoes along with an option of grilled ham and / or bacon and / or sausage. 5) Akuri or Akoori is a Parsi breakfast egg preparation very popular in Indian hotels. It has the texture of scrambled egg with the addition of onions, tomatoes, bell peppers, coriander leaves and optional spices. 6) Egg Bhurji is also an Indian egg speciality dish, where the masalas are well blended in the scrambled egg along with chopped green chillies and cooked well to a drier texture than creamy. VARIETIES OF EGGS USED IN THE KITCHEN : The most popular type of egg served in the hotels is chicken eggs, but there is also a use of different types of eggs. They are mainly eggs from other birds which are are follows :  Hen – available in two varieties, white and brown.  Turkey – about twice the size of chicken eggs.  Guinea fowl – can be boiled and made into salads,  Ducks – darker and larger than chicken eggs and the second most popular variety.  Geese – similar to duck eggs and has more fat content.  Ostrich – huge is size and weighs around 500 grams, about 10 times the normal eggs.  Quail – Very small, about 1/3rd size of a chicken egg. GRADES OF EGGS : Eggs are graded in terms of quality of the shell, egg white and egg yolk. It is important to know the different grades of eggs as that will help the chef in choosing the best egg for the use thus eliminating the eggs that are below standard. The general grading of eggs are as follows : Grade Shells Egg white quality Yolk quality AA Clean without cracks Clear and smooth Rounded A Fairly clean without cracks Fairly Clear and smooth Fairly centered B Slightly strained Loose albumin Off centered and flat C Moderately strained Very loose and watery Very flat and broken STORAGE OF EGGS : Eggs are stored in a refrigerator for daily use on trays that are specially meant for holding the eggs properly in a stable manner without breaking the egg shell. Presently eggs are are available frozen which are pasteurized before packing. Even egg yolks are available in frozen packets which are conveniently used for making dishes where raw eggs are used. Frozen eggs once thawed must be used immediately and should not be refrozen as there will be chances of bacterial growth. Care should be taken while handling eggs especially when they are fresh as they tend to detoriate when the shell is broken. The following points should be taken into account while storing fresh eggs. 1) Fresh eggs should be used as early as possible within 4 weeks. They should be stored unwashed as washing can make it susceptible to bad odours. 2) Eggs should be stored with the pointed egg down and well refrigerated. 3) Strong foods should not be stored along with eggs as egg shells are permeable and can easily catch odours. 4) Once boiled, eggs can be used for 3 days only if left unshelled. 5) It is advisable to keep eggs in plastic crates as cardboard crates can breed germs or attract pests and rodents.