The document discusses eggs, including their composition, purchasing, types, functions in foods, preparation, and storage. It describes the main components of eggs as the yolk, albumen, and shell. It covers USDA egg grading and types of specialty eggs available. The functions of eggs in foods include emulsifying, binding, and foaming. Preparation methods include dry-heat and moist-heat cooking. Eggs should be refrigerated and cooked thoroughly for safety.

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Understanding Food Principles and Preparation • Fifth Edition
AMY BROWN
© Cengage Learning 2015
Eggs
12

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Composition of Eggs

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• Yolk
– 30% of egg’s weight
– Nutrient-dense
• Albumen (egg white)
– 58% of egg’s weight
– Large amount of water
– Viscose layers
Composition of Eggs (cont’d.)

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• Shell membranes
– Protect from bacteria
• Air cell
– Provide chick with oxygen for first breath
• Shell
– 12% of egg’s weight
– Protects egg
Composition of Eggs (cont’d.)

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• Inspection
– USDA Poultry Division
– Restricted eggs: those that fail inspection &
are not sold whole to consumer
• Checks: cracked shells
• Leakers: cracked shells & membranes
• Dirties: at least one-fourth of shell covered in dirt or
stains
• Inedibles: greenish egg whites, or fertilized, rotten,
moldy, or bloody
• Meat spots: blood spots
Purchasing Eggs

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• Grading
– Optional, paid for by egg producer
– USDA grades AA, A, and B
– Methods for grading
• Candling: holding egg against light to see defects
through shell
• Measuring Haugh units: comparing height of egg
white
• Evaluating appearance: shell, white, yolk, and air
cell
Purchasing Eggs (cont’d.)

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Purchasing Eggs (cont’d.)

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Purchasing Eggs (cont’d.)

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Purchasing Eggs (cont’d.)

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Purchasing Eggs (cont’d.)

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• Egg substitutes
– Made in response to consumer demand for
low cholesterol egg products
– Often have higher sodium content than eggs
Purchasing Eggs (cont’d.)

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• Value-added eggs
– Special nutrient content or conditions under
which hens are raised
• Hen diet can lower cholesterol, and increase
omega-3 fatty acids and vitamin E
– For animal-friendly consumers, eggs from
hens that are free roaming, cage free, or fed
naturally
Purchasing Eggs (cont’d.)

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Types of Eggs

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Types of Eggs (cont’d.)

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• Emulsifying
• Binding
• Foaming
• Interfering
• Clarifying
• Color
Functions of Eggs in Foods

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Functions of Eggs in Foods (cont’d.)

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Functions of Eggs in Foods (cont’d.)

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Calorie Control: Egg Breakfast

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Preparation of Eggs

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• Changes in prepared eggs
– Effects of temperature and time
• Coagulation temperatures
– Effects of added ingredients
– Color changes
Preparation of Eggs (cont’d.)

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• Dry-heat preparation
– Fried
• Sunny-side up, over easy, over medium, over hard,
scrambled, omelets
– Baking
• Shirred eggs, meringues, and soufflés
Preparation of Eggs (cont’d.)

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Preparation of Eggs (cont’d.)

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• Moist-heat preparation
– Hard or soft “boiling”
• Hot-start method vs. cold-start method
– Coddling and poaching
– Custards
• Sweet & savory custards, stirred custards, and
baked custards
– Microwaving
• Fried, scrambled, poached, omelet, and quiche
Preparation of Eggs (cont’d.)

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• Refrigerator
– Store whole eggs in their container
– Shelf life of refrigerated eggs
• Whole eggs: ~1 month
• Separated egg yolks submerged in water: 2 days
• Egg whites in glass container: 4 days
• Storage eggs (commercial use): up to 6 months
– Pasteurized eggs for commercial use
• Liquid, frozen, or powdered; for convenience
Storage of Eggs

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• Frozen eggs
– Can’t freeze whole egg in shell; first crack
open egg and then freeze
• Drawbacks include: cost, hard to portion, and
lower quality
– Egg whites or yolks can be frozen
• At home, add 1 T of sugar or ½ t of salt for every
cup of blended eggs
• Separated egg whites need nothing added before
freezing
Storage of Eggs (cont’d.)

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• Drying eggs
– Whole eggs or yolks are dried to a fine
powder
– Egg whites are dried to granule, flake, or
milled texture
– To use, add water or by mix in with dry
ingredients
Storage of Eggs (cont’d.)

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• Buy only refrigerated eggs
• Check carton to make sure eggs are clean
and not cracked
• Do not add raw eggs to scrambled eggs
• Use an egg separator rather than passing
yolk back and forth between shells
• Ensure egg shells are not in food products
• Cook eggs until no visible liquid remains
Safety Tips

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• Bake egg dishes until an inserted knife
comes out clean
• Hold scrambled eggs at appropriate
temperatures
• Be cautious when preparing barely cooked
egg dishes (mousse, meringue, etc.)
– Heat egg dishes to 160°F (145°F for
commercial dishes)
• Do not consume raw or undercooked eggs
Safety Tips (cont’d.)

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• Use only pasteurized eggs for dishes
where eggs are cooked lightly or left raw
• Always store eggs in the refrigerator
– Unopened liquid egg products can be stored
for 7 days, but should be used within 3 days
of opening
Safety Tips (cont’d.)

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• Dried egg mix should be used within 7 to
10 days of opening
• Cold egg dishes should be stored below
40°F; hot dishes should be kept above
140°F for up to one hour
Safety Tips (cont’d.)

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• Egg protein is so high in quality that it has
become the standard (reference protein) by
which researchers rate all other food proteins
• The versatility of eggs, whether prepared
alone or in combination with other foods,
makes them nearly indispensable in cooking
• Important aspects for food preparation
– Composition, purchasing criteria, types and
functions of eggs, and preparation and storage
techniques
Chapter Summary