Egg Information Center

Nature designed eggs as the food source for developing chicks. Eggs, particularly chicken eggs, are also an excellent food for humans because of their high protein content, low cost and ready availability.

They are extremely versatile and are used throughout the kitchen, either served alone or as ingredients in a prepared dish. Eggs are used to provide texture, flavor, structure, moisture and nutrition in everything from soups and sauces to breads and pastries. High quality and freshness are critical for their proper use. Learn to select the finest products, and handle them with care.

Composition
The primary parts of an egg are the shell, yolk and albumen. The shell, composed of calcium carbonate, is the outermost covering of the egg. It prevents microbes from entering and moisture from escaping, and also protects the egg during handling and transport.

Shell color is determined by the breed of the hen; for chickens, it can range from bright white to brown. Shell color has no effect on quality, flavor or nutrition. The yolk is the yellow portion of the egg. It constitutes just over one third of the egg and contains three fourths of the calories, most of the minerals and vitamins and all the fat.

The yolk also contains lecithin, the compound responsible for emulsification in products such as hollandaise sauce and mayonnaise. Egg yolk solidifies (coagulates) at temperatures between 149ºF and 158ºF (65ºC-70ºC). Although the color of a yolk may vary depending on the hen's feed, color does not affect quality or nutritional content. The albumen is the clear portion of the egg and is often referred to as the egg white. It constitutes about two thirds of the egg and contains more than half of the protein and riboflavin.

Egg white coagulates, becoming firm and opaque, at temperatures between 144ºF and 149ºF (62ºC-65ºC). An often-misunderstood portion of the egg is the chalazae cords. These thick, twisted strands of egg white anchor the yolk in place. They are neither imperfections nor embryos. The more prominent the chalazae, the fresher the egg. Chalazae do not interfere with cooking or with whipping egg whites.

Eggs are sold in jumbo, extra large, large, medium, small and peewee sizes as determined by weight per dozen. Food service operations generally use large eggs.

Type of Eggs
When most people refer to an "egg," they mean a chicken's egg. But other eggs are sometimes used in the kitchen: Bantam egg: The egg from a breed of small chicken; it is about half the size of a regular chicken egg and has the same characteristics. Duck egg: It has an off-white shell and a rich flavor and higher fat content than a chicken's egg; when boiled, the white turns bluish and the yolk turns red-orange. Goose egg: White-shelled, it is four to five times larger than a chicken egg and has a somewhat richer flavor. Guinea fowl egg: An egg with an ivory shell flecked with brown; it has a more delicate flavor than that of a chicken egg. Gull egg: Its shell is covered with light to dark brown blotches and comes in various small sizes; the egg has a

slightly fishy flavor. Ostrich egg: twenty times as large as a chicken egg its shell is thick and ivory-colored. Partridge egg: A small egg with a white, buff or olive shell and a mild flavor Quail egg: A richly flavored egg, it is small with a speckled brown shell. Turkey egg: A large egg with a brown shell and a delicate flavor Turtle egg: A reptile's egg with a mild, rich flavor; its soft shell is buff or speckled.

Grading
The USDA or a state agency following USDA guidelines grades eggs. The grade AA, A or B is given an egg based upon interior and exterior quality, not size. Grade has no effect on nutritional values.

Storage
Egg quality is quickly diminished by improper handling. Eggs should be stored at temperatures below 40ºF (4ºC) and at a relative humidity of 70% to 80%. Eggs will age more during one day at room temperature than they will during one week under proper refrigeration.

As eggs age, the white becomes thinner and the yolk becomes flatter. Although this will change the appearance of poached or fried eggs, age has little effect on nutrition or behavior during cooking procedures. Older eggs, however, should be used for hard cooking, as the shells are easier to remove than those on fresh eggs.

EGG GRADES

	Grade AA	Grade A	Grade B
Spreads	Remains compact	Spreads Slightly	Spreads over wide area
Albumen	Clear, thick and firm; prominent chalazae	Clear and reasonably firm; prominent chalazae	Clear; weak or watery
Yolk	Firm; centered; stands Round and high; free From defects	Firm; stands fairly high; practically free from defects	Enlarged and flattened may show slight defects
Shell	Clean; of normal shape	unbroken	Slight stain permissible Abnormal shape
Use	Any use especially frying, poaching and Cooking in shell	Any use especially frying, poaching and Cooking in shell	Baking, scrambling used in bulk egg products

Cartons of fresh, uncooked eggs will keep for at least four to five weeks beyond the pack date if properly refrigerated. Hard-cooked eggs left in their shells and refrigerated should he used within one week.

Store eggs away from strongly flavored foods to reduce odor absorption. Rotate egg stock to maintain freshness. Do not use dirty, cracked or broken eggs as they may contain bacteria or other contaminants. Frozen eggs should be thawed in the refrigerator and used only in dishes that will be thoroughly cooked, such as baked products.

Sanitation
Eggs are a potentially hazardous food. Rich in protein, they are an excellent breeding ground for bacteria. Salmonella is of particular concern with eggs and egg products because this bacteria is commonly found in a chicken's intestinal tract.

Although shells are cleaned at packing houses, some bacteria may remain. Therefore, to prevent contamination, it is best to avoid mixing a shell with the liquid egg. Inadequately cooking or improperly storing eggs may lead to food-borne illnesses.

USDA guidelines indicate that pasteurization is achieved when the whole egg stays at a temperature of 140ºF (60ºC) for 3.5 minutes. Hold egg dishes below 40ºF (4ºC) or above 145ºF (63ºC).

Never leave an egg dish at room temperature for more than one hour, including preparation and service time. Never reuse a container after it has held raw eggs without thoroughly cleaning and sanitizing it.

Egg Products
Food service operations often want the convenience of buying eggs out of the shell in the exact form needed: whole eggs, yolks only or whites only. These processed items are called egg products and are subject to strict pasteurization standards and USDA inspections. Egg products can be frozen, refrigerated or dried. Precooked, preportioned and blended egg products are also available.

Egg Substitutes
Concerns about the cholesterol content of eggs have increased the popularity of egg substitutes. There are two general types of substitute. The first is a complete substitute made from soy or milk proteins. It should not be used in recipes where eggs are required for thickening. The second substitute contains real albumen, but the egg yolk has been replaced with vegetable or milk products. Egg substitutes have a different flavor than real eggs, but may be useful for persons on a restricted diet.

Nutrition
Eggs contain vitamins A, D, E, K and the B-complex vitamins. They are rich in minerals and do not contain as much cholesterol as was once feared. In fact, the American Heart Association now suggests that it is acceptable to consume up to four egg yolks per week as part of a balanced diet.