Functions of an egg in food preparation

The functions of eggs in food preparation can be classified according to different properties of an egg. The three functional properties of relevance to food preparation are; coagulation, emulsification and foaming.
a. Coagulation
The proteins of eggs coagulate during cooking. The egg white protein coagulates at temperatures ranging between 60oC to 65oC. This is associated with a loss of translucency; the white becomes opaque and it no longer flows. When the egg white has reached 70oC it turns firm. The egg-yolk proteins coagulate at a slightly higher temperature than egg-white proteins. Coagulation begins at 65oC and the flow properties are lost at 70oC. If overcooked, the protein squeezes together leaving little room for the pockets of water. Whole egg dishes such as boiled, poached and fried eggs become rubbery and egg dishes with added liquid, such as scrambled egg and egg custard, separate to produce lumps of protein and a watery liquid. This is known as syneresis.
b. Thickening properties
The protein in eggs will thicken when heated and become firm. If an egg is overheated or cooked for too long of a time it will become rubbery and tough in texture. Eggs are often used in custards and sauces to thicken the finished product.
c. Emulsifier : Egg yolk contains lecithin which is an emulsifying agent. The emulsifying properties of an egg yolk are used in the preparation of cakes and mayonnaise. If vinegar and oil are shaken up together and left to stand, the liquids separate, with the oil forming the top layer and the vinegar the bottom layer. Such liquids are immiscible. If an emulsifying agent such as egg yolk is used, the 2 liquids are held together as an emulsion. Mayonnaise is an emulsion of oil in vinegar. The oil is suspended in minute droplets in vinegar, and this mixture is stable because of the lecithin from the egg yolk. Emulsifying agents have one part of the molecule which attracts water (hydrophilic) and another part which does not (hydrophobic). In an emulsion of this kind the molecules of lecithin surround the oil droplets with the hydrophilic part of the molecule in the vinegar and the hydrophobic part in the oil droplets.
d. Foaming
When egg white is whisked, bubbles of air are incorporated into it forming an egg white foam. When egg white is beaten they become foamy. During the early stages of beating, the bubbles of air are large and tend to coalesce or join together. If beating is stopped the egg white drains away from the air bubbles. As the beating is continues the air bubble becomes smaller, and the liquid egg white forms a thin film around each bubble. If the beating is continued the foam becomes thicker, with smaller air bubbles, and whiter, eventually forming soft rounded peaks. As beating progress the peaks becomes stiff and pointed. Cooking brings about coagulation of the foam which makes it permanent.
e. Binder
A binder helps other ingredients bind together (eggs are used to help bind together meatballs, meatloaf and flour mixtures). When eggs are heated they coagulate, this helps stick together the ingredients they are mixed with.

f. Coating agent
The breading on fried chicken sticks because the chicken is dipped into an egg then a flour or crumb mixture. The eggs help hold the crumb mixture to the food when heated during the cooking process.
g. crystallization
When a liquid freezes, ice crystals form. When eggs are added to a mixture, it helps prevent these crystals from forming. That is why another use of eggs is the prevention of crystallization.
h. Clarifier
The egg is used to make a broth clear. Any unwanted particles in the broth will stick to the egg as it coagulates in the broth. The cooked egg is then removed.
i. Leavening
One of the most common uses of eggs is as a leavening agent. A leavening agent helps to make a cooked product rise. When eggs are beaten they hold air. When heat is added the structure will coagulate and traps the air. This is what gives a gel food cakes their light and fluffy texture.
j. Enriching; egg can be added to squashes, milk puddings soups, etc, as away of including extra protein.
k. Garnishing; slices of hard-boiled eggs can be served with food for purpose of garnishing. .

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Titany answered the question on April 25, 2022 at 08:54