The Structure of Eggs

1. The Structure of Eggs • The hard shell is porous and lined with membranes. • A pocket of air, known as the air cell, lies between these membranes at the wide, round end. • As an egg ages, the air cell gets larger.

2. The Structure of Eggs • Also known as the egg white, the albumen is the thick fluid surrounding the egg yolk. • The albumen gets thinner as an egg ages. • Very fresh eggs have a cloudy-white albumen.

3. The Structure of Eggs • The round yellow portion of an egg is the yolk. • It is encased in a thin membrane and floats within the albumen. • The yolk flattens as an egg ages. • Color depends on the hen’s diet. • The two, thick, twisted strands of albumen that anchor the yolk in the center of an egg are called the chalazae. • The thicker and more prominent the chalazae, the fresher the egg.

4. Nutrients in Eggs • Excellent source of protein and vitamin B12. • Both the white and the yolk contain protein. • The yolk of the egg contains more vitamins and minerals than the white. • Yolks also contain fats and cholesterol. • The color of the egg shell is not related to its nutrients, flavor, or cooking qualities. • The color of the shell is determined by the breed of the hen.

5. Egg Grade • A USDA grade shield on a package means that the eggs have been federally inspected for wholesomeness. • Determined by the inner and outer quality of the egg. • Inspect using bright lights. • The three egg grades are AA, A, and B. • Supermarkets typically carry AA & A. • Appearances differ when cooked. • AA & A have a thicker white. • Use Grade B for Baking

6. Egg Size • The egg sizes most commonly sold are medium, large, extra large, and jumbo. • Most recipes assume that large eggs will be used. • The price of eggs depends on the size as well as the supply of various sizes. • Size can vary slightly in the same carton.

7. Egg Storage • Eggs are highly perishable. • Take eggs home and refrigerate them in their original carton. • Exposed to warm air in the door. • Eggs are porous and may lose quality and pick up aromas and flavors from other foods. • Do not wash eggs. • This could remove the protective coating that prevents bacteria from getting inside the shell. • Raw eggs stay fresh for up to 4 weeks.

8. Egg Substitutes • Egg substitutes are an alternative to whole eggs. • They are made by combining egg whites with oils. • You can use substitutes the same as whole eggs. • Because they contain no egg yolks, egg substitutes have no cholesterol or fat and are lower in calories. • They lack some B vitamins. • More expensive.

9. Egg Science • Eggs have special properties that result from their high protein content. • They can act as: • A Binder • A Thickener • A Leavening Agent • An Emulsifier • Because of their many uses, they are found in a wide variety of recipes.

10. Eggs as a Binder • How an egg acts as a binder: • The proteins in eggs are shaped like coils. • When the proteins are heated, the coils unwind and join loosely with other proteins. • The new structures form pockets that hold water. • The pockets absorb moisture, and the egg changes from a liquid to a solid state. • This transformation is called coagulation. • Coagulation is what helps eggs act as a binder in foods like meatloaf, and thickens custards such as pumpkin pie.

11. Eggs as an Emulsifier • An emulsifier is a substance that holds together two liquids that normally do not stay mixed, such as water and oil. • How does this work? • In yolk protein, one end of the amino acid bonds with water, but the other end bonds with oil. • This gives egg yolks the power to hold 2 ingredients together. • Examples: • Vinegar and oil in a salad dressing. • Lemon juice and oil in mayonnaise.

12. Eggs as a Leavening Agent • Egg whites act as leavening agents. • When you beat egg whites, air enters the mixture and a foam forms. • An egg white foam adds volume and lightness to baked products such as angel food cake and soufflés.

13. Separating Eggs • Different parts have different uses. • Yolks are used in custards, sauces, mayonnaise, and pastry. • Whites are used in meringues and baked items. • To separate an egg: • Use an egg separator. • Helps keep the yolk from bursting and running into the white. • Eggs separate more easily when cold.

14. Cooking Eggs in the Shell • Place a single layer of eggs in a saucepan. • Add water to at least 1 inch above the eggs. • Cover the pan and bring the water to a boil. • Cooking time: • 12 minutes for medium-size eggs • 15 minutes for large eggs • 18 minutes for extra large eggs • Do NOT cook less than 12 minutes! • Pour off hot water and run cold water over the eggs. • Refrigerate them in their shells until ready to use.

15. Poaching Eggs • Poached eggs are cooked in simmering water. • Crack the egg right into the simmering water. • Cook about 3-5 minutes. • Use a slotted spoon to remove. • Little to no fat is used. • Usually served with Hollandaise sauce. • Eggs Benedict

16. Scrambling Eggs • Scrambled eggs are beaten, then fried. • To make fluffy scrambled eggs, beat the eggs with water. • How to prepare: • Pour the beaten egg mixture into a heated skillet. • As the mixture starts to thicken, lightly stir the eggs with a spatula. • Continue until the eggs are thickened and there is no liquid. • Do not stir the eggs constantly. • This beats out the air and creates small, tough pieces.

17. Baking Eggs • Baked eggs, also known as shirred eggs, are eggs baked in a greased, shallow dish and are often topped with a small amount of milk. • Eggs can also be baked into a quiche. • A quiche is a pie with custard filling, containing such foods as chopped vegetables, cheese, and chopped, cooked meat.

18. Omelets • An omelet is an egg mixture formed into a large, thick pancake, usually filled with ingredients and folded. • Unlike scrambled eggs, the eggs in an omelet are not stirred. • A frittata is an unfolded omelet with fillings stirred into the egg mixture.