Eggs!
Chapter 16
Draw and label the parts of the egg in your notes.
Air Cell
Shell
Membrane
Yolk
White
Chalazae
Nutritional Value
• One of the best sources of complete
proteins
• Many vitamins and minerals
• Yolks are high in cholesterol
• Egg whites are cholesterol free
Egg Grades
• For retail sell they must be graded.
• 4 factors determine grade
– Condition of the shell
– Size of air cell
– Clearness and thickness of white
– Condition of yolk
Egg Grades
• Graded for quality by a system called
candling. (looking for the 4 factors)
– Eggs move along rollers over bright lights.
– Lights illuminate the eggs’ structure.
– Skilled people can then look at the eggs
carefully and remove any that do not meet
standards.
– Called candling because candles were used
originally - no electricity.
Egg Grades
• 2 main grades available in supermarkets
• Look for grades listed on egg cartons
• Grade AA
– Clean, unbroken shell with small air cell, when
egg is broken yolk stands tall, white is thick,
clear and covers a small area.
• Grade A
– Clean, unbroken shell with slightly larger air
cell, when broken white covers a larger area.
Egg Size and Color
• Eggs are sized on the basis of a medium weight
per dozen.
• Extra large, large and medium eggs are the
most common sizes sold.
• Most recipes use medium or large eggs
• Extra large cost the most, medium the least.
• Size has no relation to quality
• Breed of chicken determines egg color.
• Shell color does not affect quality, flavor or
nutritional value.
Storing Eggs
• Buy eggs only from refrigerated cases if at a
store!
• Check to make sure no eggs are dirty or broken
before buying.
• Cracked eggs may contain dangerous bacteria.
• Eggs should go immediately in the refrigerator
• Store fresh eggs may remain in the refrigerator
for 4-5 weeks.
Storing Eggs
• Some recipes call only for egg yolks or
egg whites
• To store leftover yolks cover them with
cold water and refrigerate in a tightly
covered container
• To store egg whites, refrigerate them in a
tightly covered container.
• Use yolks within one or two days
• Use whites within four days.
Eggs as Ingredients! : Emulsifiers
• An emulsion is the mixture that forms when you
combine liquids that ordinarily do not mix. (oil,
vinegar, water and water based liquids)
• Temporary
– Shake them and ingredients combine, leave alone
and they separate (Italian Dressing)
• Permanent
– Will not separate because an emulsifying agent has
been added – most commonly egg yolks
(Mayonnaise)
Eggs as Ingredients! : Foams
• Used to add air to foods (Angel food cake)
• Factors that affect foams
– Temperature, beating time, fat, acid and sugar.
• Temperature
– Eggs separate best when cold
– Egg whites reach max. volume when at room
temperature.
• Beating time
– Under beating causes them to fall after a short time
because they won’t hold their shape.
– Over beating makes the foam break down into curds.
Eggs as Ingredients!: Foams
• Fat
– Inhibit the formation of foam.
– Very important to not have ANY yolk in bowl (yolks
contain fat …cholesterol specifically)
– Clean beaters – dirty beaters may have fat on them
(think butter from cookies)
• Acid
– Makes foams more stable (cream of tartar)
• Sugar
– Increases stability and beating time also.
Eggs as Ingredients!: Foams
• 3 stages: Foamy, soft peak, hard peak
• Foamy
– Transparent, bubbles and foam on surface, will run
out of bowl if you try to pour it.
• Soft Peak
– White and shiny, when you lift the beater foam stands
in peaks that bend at the tips
• Hard Peak
– White and shiny, when you lift the beater foam stands
in strait peaks.
Eggs as Ingredients!: Thickeners
• Heat causes egg proteins to coagulate
(thicken)
• When adding eggs to a hot mixture to
thicken you need to first add a small
amount of the hot to the beaten eggs, stir
then add warmed egg mixture to the hot.
• This keeps eggs from curdling or cooking
into lumps.
Eggs as Ingredients!: Binding and
Interfering Agents, Structure
• Binding
– Hold things together like and meatloaf.
• Interfering
– Inhibit the formation of ice crystals in frozen
foods like custard and ice cream.
• Structure
– Add structure to baked products like cookies
and cake
Food Science Principles
• Eggs coagulate when heated during
cooking.
• Egg white coagulates at a slightly lower
temperature than the yolk. –below boiling
for both.
• Use low to moderate temps for cooking so
eggs do not dry out or get tough.
Methods of Cooking
• Safely cooked eggs have completely set
whites and thickened yolks.
• Yolks do not need to be hard but should
not be runny.
• Dishes with eggs like breakfast
casseroles, quiches, soufflés should reach
160
• When cooking eggs in a skillet pre-heat
the skillet and any fat you may be using.
Homework
• On a piece of notebook paper simplify the
directions in the book for each of the following:
– Due tomorrow (pg 308-9)
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Microwaving eggs
Omelets
Soufflés
Meringues
Custards