Eggs and Egg Cookery
Chapter 24
Use of Eggs
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Emulsions (Lecithin in yolk)
Foam
Coagulation
Clarifying agent
Color
Flavor
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Composition
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Whole Eggs
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75% water
12% protein
10% fat
1% carbohydrate
1% minerals
Egg White
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Egg Yolk
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88% water
4g protein
0g fat
Trace minerals
49% water
3g protein
5g fat
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Nutritive Value
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Protein
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High protein efficiency
ratio (PER)
Whites
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Triglycerides
Phospholipids
Cholesterol
Ovalabumin
Yolks
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Lipids
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Lipoproteins
Pigments
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Xanthophyll
Vitamin A
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Air cell
Chalazae
Shell
Yolk
Vitelline Membrane
Thick White
Thin white
Basic parts of the egg
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Structure
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Egg Shell
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Porous
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Shell color has no impact (flavor or nutrition)
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Protective coating
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Allows exchange of gas and moisture
Cuticle or Bloom
Replaced with oil after washing
Air Cells
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Become larger as egg ages
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Structure
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Albumen
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Chalazae
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Egg white
Consists of thick and thin portions
Thickened “rope-like” white that anchors yolk
Membranes
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Thin membrane that surrounds yolk
Shell membranes
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Structure
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Yolk
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Composed of protein granules and oil droplets
within spheres
Germinal disc
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No difference between fertile and infertile eggs
Blood spots
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Because of blood vessel rupture on surface of yolk
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Egg Quality
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Fresh eggs
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Stand high when broken
onto a plate
Yolk stands high and round
Two “layers” of egg white
evident
Small air cells
Yolks are slightly acidic
Older egg
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Spreads out when broken
onto a plate
Yolk does not stand high
and round
One “layer” of white that
spreads out
Large air cells
Egg becomes more alkaline
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Egg Flavor and Odor
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Affected by
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Feed
Hen
Storage
Introductory Foods, 13th ed.
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Purchasing & Quality
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Purchasing
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Pack date
USDA grading
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Quality measurement
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U.S. Grade AA, Grade A, or Grade B
Candling
Sizing
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Recipes standardized for large eggs
Consider cost of eggs per dozen
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Food Safety
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1 out of 20,000 eggs contaminated with Salmonella
enteritidis
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About 2.3 million eggs contaminated
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Unbroken eggs may be contaminated
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Raw or undercooked eggs implicated in about 80
percent of foodborne illness outbreaks
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Regulation & Processing
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Safe food handling instructions must be on
cartoons
Eggs must be held and displayed at or below
45°F (7°C)
Some eggs may be
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Pasteurized
Irradiated
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Recommendations
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Avoid cross-contamination with raw eggs
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Do not eat raw eggs
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Cook over moderate heat
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Use pasteurized eggs for high-risk populations
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Preservation and Processing
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Processed egg products
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Frozen
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Yolks frozen with salt or sugar for stabilization
Dried
Liquid
Other
Pasteurization required of all processed eggs
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Egg Substitutes
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Provide a low-cholesterol egg product
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Contain
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No or very little yolk
High concentration of egg white
Additional ingredients may include
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Corn or soybean oil
Nonfat dry milk
Soy protein isolate
Egg white solids
Calcium caseinate
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Heat Coagulation
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Heat denatures egg proteins
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Proteins aggregate into a three dimensional gel
network
Network stabilized by cross bonds
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Disulfide bonds
Hydrogen bonds
Coagulation proceeds gradually
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Heat Coagulation
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Egg yolks vs. egg whites
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Diluted eggs (i.e. diluted with milk)
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High temperatures
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Promote toughness and shrinking
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Rapid heating
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Influence of the addition of
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Sugar, Salt, Acid
Introductory Foods, 13th ed.
Bennion and Scheule
18
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Coagulation by Beating
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Beating causes part of the proteins to become
coagulated
Egg whites
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Whole eggs
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Become foamy, then form soft and stiff peaks
Over beaten – then dry and flocculated
Will beat stiffer
Egg yolks
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Increase slightly in volume
Introductory Foods, 13th ed.
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19
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Egg White Foams
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Thin whites – more fluffy, less body
Thick whites – more stable foam
Room temperature – greater volume
Fine beater wires – finer air cells
Bowl type
Introductory Foods, 13th ed.
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Egg White Foams
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Impact of added substances
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Fat
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Salt
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decrease volume and stability
Acid (Cream of Tartar)
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interferes
increases stability
Increases whipping time
Sugar
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Introductory Foods, 13th ed.
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increases beating time
Increases stability
21
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Egg Preparation Methods
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Poached
Cooked in shell
Fried eggs
Scrambled eggs
Shirred eggs
Omelets
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French
Puffy
Introductory Foods, 13th ed.
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Crêpes
Soufflés
Custard
22
Baked
Soft or Stirred
Meringues
Microwave cooking
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Upper Saddle River, NJ 07458. • All Rights Reserved.
Why do eggs turn green!
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Overcooking
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Held hot – too long
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Older (more alkaline eggs) are more
susceptible
Green color caused by
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Reaction of iron in yolk with hydrogen sulfide
in white to produce ferrous sulfide
Introductory Foods, 13th ed.
Bennion and Scheule
23
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.