Eggs contain antioxidants (lutein and zeaxanthin) that may benefit eye health; choline which may have a helpful effect on brain function. They are low in calories and provide an excellent source of protein. But because eggs are high in cholesterol, people have been limiting their consumption for years. Researchers now believe that eggs can be a part of a heart-healthy diet. The American Heart Association says that as long as a person's diet limits cholesterol from other sources, they can enjoy up to an egg per day.
ANATOMY OF AN EGG
The shell - consists of 2 fine layers of calcium carbonate. The layers do separate over time, creating a void called the "air cell." This space causes older eggs to float in a glass of water while very fresh eggs will sink to the bottom.
The egg white - is also called the albumin. A cloudy egg indicates a very fresh egg. The white consists of water and protein and provides slightly more than half of the egg's protein.
The yolk holds all the egg's fat; cholesterol; vitamins A, D and E; and the other half of the protein. The color of the yolk depends on the hen's diet and does not affect nutritional content.
A large egg contains 75 calories, 5 grams of fat, and 6.3 grams of protein. The American Heart Association recommends that people limit their dietary intake of cholesterol to 300 mg. A large egg contains about 213 mg.
The breed of hen determines the color of an egg's shell. The color has no impact on the egg's nutrition profile, and there are no flavor differences between brown and white eggs.
Eggs are sized from peewee to jumbo. The terms refer to the weight of the eggs per dozen, not to the dimensions of an individual egg. A dozen jumbo eggs must weigh 30 ounces; a dozen extra large eggs will weigh 27 ounces; large eggs will weigh 24 ounces; medium eggs will weigh 21 ounces. Smaller eggs do not show up in the marketplace.
You can make size substitutions in dishes such as scrambles and omelets; however, for best results with baking, use the size of the egg called for in the recipe. If no size is specified, assume it is large.
Buy the freshest eggs available (check the sell-by date) and always from a refrigerated case. Once you are home, refrigerate immediately in the original carton, which prevents moisture loss and absorption of odors from other foods in the refrigerator. Discard any eggs with cracks. Store on an inside shelf and not in the egg "cups" on the door where the temperature isn't as cold.
Raw eggs can be stored in the refrigerator for three to five weeks from date of purchase. The sell-by date may pass within this period but the eggs are still safe to use. Hard-cooked eggs should be refrigerated within 2 hours of cooking and used within a week. Raw eggs can be brought to room temperature in 20-30 minutes in order to improve their whipping qualities.
When beaten, egg whites increase in volume by six to eight times. In order to get the fluffiest egg whites, it is important to carefully separate the eggs; if any yolk gets into the whites, they will not beat to their maximum volume. You are less likely to break the yolk when separating by using an inexpensive egg separator. Eggs are easiest to separate when they are cold; whites beat best at room temperature.
MAKING THE GRADE
About one-third of eggs in the marketplace are graded for quality and checked for weight by a USDA inspector. These cartons are stamped with the date packed (as opposed to a sell-by date). The date is a Julian date, meaning the day of the year (for example: January 9th is represented by 009, and December 31st is 365).
Egg packers who do not use the USDA grading service put terms such as "Grade A" on their egg cartons without the USDA shield. Their compliance with grade, weight (size) and other requirements is monitored by state agencies. There are three consumer grades for eggs: AA eggs have thick, firm whites and high, round yolks; grade A have reasonably firm whites and high, round yolks; B grade eggs have thinner whites and flatter yolks and are seldom found in retail stores. Grade AA and A will perform equally well in all applications.
Some egg producers use special bird feeds to enhance the amount of omega-3 fatty acids in their eggs. These special eggs cost more than regular eggs, ranging from one to two dollars more per dozen.
Some producers feed their hens a diet high in flaxseed, a good source of omega-3s, and the fatty acids are transferred to the eggs. Such eggs contain about three to six times the amount of omega-3 fatty acids than regular eggs. The total fat content, however, is the same as regular eggs.