EGGS!
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What we’re doing today
folks!
History
 Etiology
 Health
 Dissecting the egg
 Good Egg, Bad Egg
 Cooking
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Background History
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300 mya- eggs laying in the ocean
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100 mya- mineralized egg shell
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8 mya- Gallus genus formed
3-4 mya- Gallus gallus chicken species
formed
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7500 BCE domestication SE Asia
Background History
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Egg + Sperm = Fertilization ->
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Egg + no sperm =
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Health - Allergies
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Cause from ovalbumin NOT the yolk
Ovalbumin mounts an attack and
human immune system over attacks.
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Health- Salmonella
enteritidis: Symptoms
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6-72 hrs
Gastrointestinal Illness
1:10,000 eggs w/ Salmonella
“Hugging the toilet”
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Health- Salmonella: Most
Susceptible
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Young & Old: WHY???
How does it spread???
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SO:
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Buy Refrigerated
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Cook completely
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– 140ºF 5 min
– 160ºF 1 min.
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Health- Salmonella: Safe
Alternative
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Pasteurized @ 130-140ºF
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Liquid eggs
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Dried whites
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Health - Cholesterol
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1970’s-1980’s PHOBIA
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Health – Cholesterol:
Misconception
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1 Lg egg: 215 mg = meat 50 mg
Blood cholesterol
Heart Risk
Blood cholesterol influenced by Saturated
fats. HOWEVER: most egg yolks are
unsaturated fats.
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Health – Cholesterol:
Substitutes

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REAL egg whites
Imitation yolk: Veggie Oil
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Milk Solids
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Gums
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Dissecting The Egg
1. Cuticle
2. Shell
3. Whites
4. Yolk
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5. Chalaza
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Dissecting the Egg- Cuticle/Color
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Color due to proteinaceous cuticle
Cuticle plugs the pores
Color has no relation to Taste or
nutritional value
Color relates literally…
Ex. Araucana hens lay blue eggs
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Dissecting the Egg: Shell
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Derived from Hen’s uterine lining cells
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Shell composed of Calcium Carbonate
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10K
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Air pockets
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Dissecting the Egg: Chalaza
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2 chords that anchor the yolk
Will rotate while suspended in the
middle of the egg
Function: Provides stability &
cushioning
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Dissecting the Egg: Yolk

YOLK= Fuel: ¾ calories, iron, thiamin, &
vitamin A
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Pigment Plant xanthophlls (from what
hen ate) fat & protein synthesized in the
hen’s liver
White Yolk: Yellow Yolk
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Dissecting the Egg: Whites
 Thick
& Thin Whites
 Function:
– defense against Infection
– protection
– nourishment
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Whites: Nourishment

Contains
 Trace
minerals
 Fatty materials
 Vitamin (riboflavin)
 Glucose
 Water - 90%
 Proteins - 10%
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Whites: Defenses
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Acts as the primary defense against infection
& predators
Protein that blocks digestive enzymes
Protein binds to iron & vitamins so NOT useful
to other species
Protein inhibits virus reproduction
Protein that digests bacteria cell wall
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Whites: The Proteins (4 total)

Ovotransferrin (1st to coagulate)
Carries iron to developing chick
 Prevents bacteria from using iron
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Whites: The Proteins (4 total)
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Ovalbumin (most plentiful approximately 70%)
– Reactive sulfur groups
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Ovomucin and Ovomucoid (less than 2%)
– Jelly-like consistency
– Pulls together soupy proteins into organized
structure
–
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Whites: Other Proteins
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Globulins – lysozyme
Avidin – large quantities can cause
biotin deficiency
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Whites: Thick & Thin= Albumen
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Adds THICK layers to the
membrane whites
(albumen) in 4 layers for
THICK & THIN albumen
for consistency
Secreted by Oviduct from
protein secreting cells.
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Eggcelent Facts
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Commercial chicken can lay 250-290
eggs
Raw eggs in shell keep for 3-5 weeks in
refrigerator
Egg consumption has declined from 320
eggs per person in 1967 to 235 in 1990
and has increased to 254 in 2003.
Weight - 15 to 30 oz.
¼ hen’s energy goes in to egg making
– ½ for a duck
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Good Egg; Badddd Egg
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Good Egg Baddd Egg
Grades
Thick Whites Firm Round
Yolks
AA
YES
YES
A
Less Thick
Weaker
B
Fast
spreading
Easily Breaks
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Good Egg Baddd Egg
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Characteristics of a Good Egg:
– Intact
– Uncontaminated egg
– Strong Shell
– Firm Yolk
– Thick White
– HOW DO YOU KNOW W/O BREAKING
THE EGG?
– Bad eggs Normally when Hen lays eggs at
the end of the laying year
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Good Egg Bad Egg: CANDLING
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Spots cracks
Large air cells
“Meat spots”
– Brown in whites
– Tissue slough off from oviduct
wall
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Blood spots on yolk
– Burst capillaries in hen
ovary/yolk sac
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Eggs = A Hot Potato?
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Eggs quickly gathered
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Immediately Cooled
(USA) Wash in warm water
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Sold 2 days after
Deterioration: 1 Day Room Temp = 4 Days
in Fridge
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Why?
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Whites & Yolks more
alkaline (dec. Acid)
Moisture decreases
Calcium Carbonate
dissolves
pH Then
pH
Later
Whites
6.0 pH
6.6 pH
Yolk
7.7 pH
9.2 pH
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Storage

FREEZING: Air tight container
 Separate
from shell
 Whites
 Yolks
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Egg Versatility!
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Fry
Boil
Deep Fried
Baked
Roasted
Pickled
Fermented
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1.
Coagulation
2.
1. Egg
proteins
folded
chains of
Amino
Acids
3.
2. ADD Heat
and chains
UNFOLD
3. Unfolding
and chains
bond to
each other
for a
continuous
meshwork
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Coagulation cont…
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Egg white coagulation starts at 144ºF and
sets at 150ºF
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Yolk thickens at 150F and sets at 158ºF
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Yolk and white mixed set at 165ºF
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Eggs + Ingredients =
Coagulation?
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Liquid - raises thickening temp
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Sugar - raises thickening temp
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Acid and salt - thickening and
coagulation at lower temps
– Proteins do not have chance to unfold
completely
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Foam
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Egg white filled with air
Proteins unfold and bond together
(whisking causes protein to unfold)
4 stages
– “foamy”
– “soft peak”
– “stiff peak”
– “dry”
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Foam cont.
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Other ingredients
– Salt - increases whipping time/decreases
foam stability
– Sugar - delays foaming/reduces volume and
lightness BUT improves stability
– Egg yolk, oil/fat - interfere with foam
Ex. Mousses, soufflés, angle food cake, and meringues. 37Foams
help LIGHTEN a dish
Custards
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West: custards are milk or cream
Fruit & Veggies can cause curdling
EX. Crème Brûlée, Cheesecake, flan, & Quiche
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Green Eggs and Ham
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Green
yolks are
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harmless
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Ferrous
sulfide
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Power Point Author
Shauna Henley
 The University of Vermont
 Foods and Nutrition
 Basic Concepts of Food
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