food selection eggs

1. EG
GS

2. INTRODUCTION
Eggs are laid by female animals of many species,
including birds, amphibians, reptiles, and fish.
Chicken eggs are the most popular choice for egg
consumption.
They are an inexpensive source of protein.
Because of their easy availability, low cost, and
high nutritional value, chicken eggs are considered
an affordable and efficient source of protein.

4. STRUCTURE OF EGG
EGGSHELL
The outer eggshell is made almost entirely
of calcium carbonate (CaCO3) and is
covered with as many as 17,000 tiny pores.
The shell also has a thin outermost coating
called the bloom or cuticle that helps keep
out bacteria and dust.

5. CHALAZA
Strands that are twisted in opposite
directions and anchor the yolk in center
of the egg. The more prominent the
chalazae, the fresher the egg.
THIN ALBUMEN
The outer thin albumen; a narrow fluid
layer next to the shell membrane.

6. THICK ALBUMEN
The inner thick white
(chalaziferous layer) is a dense,
matted, fibrous capsule of
albumen around the vitelline
membrane of the yolk.
It's an excellent source of riboflavin and
protein.
In high-quality eggs, the inner thick

7. VITELLINE MEMBRANE
A clear seal which holds the egg yolk.
YELLOW YOLK
The yolk contains less water and protein
than the white, and most of the vitamins
and minerals of the egg.
It is also a source of lecithin; an effective
emulsifier.
Yolk color ranges from just a hint of
yellow to a magnificent deep orange,
according to the feed and breed of the

8. AIR CELL
An air space forms when the contents of
the egg cool and contract after the egg
is laid.
The air cell rests between the outer and
inner membranes at the egg's larger
end.
As the egg ages, moisture and carbon
dioxide leave through the pores of the
shell, air enters to replace them and the
air cell becomes larger.

9. GERMINAL DISC
A small, circular, white spot (2-3 mm
across) on the surface of the yolk; it is
where the sperm enters the egg.
The embryo develops from this disk,
and gradually sends blood vessels into
the yolk to use it for nutrition as the
embryo develops.
CUTICULA

10. PROTEIN CONTENT OF AN EGG
Protein content of an egg accounts to
about 12.6% by weight of the edible
portion
DISTRIBUTION OF PROTEINS IN
AN EGG
Egg white 57%
Egg yellow 43%

11. DESCRIPTION
PROTEIN
CONTENT ( PER
100g )
PROTEIN
CONTENT (%
)
Egg, Whole,
Raw, Fresh 12.56g 12.56%
Egg, White,
Raw, Fresh 10.90g 10.90%
Egg, Yolk, Raw,
Fresh 15.86g 15.86%
TABLE: PROTEIN CONTENT
OF EGGS

12. Egg, Whole,
Dried 48.37g 48.37%
Egg, Whole,
Cooked,
Hardboiled
12.58g 12.58%
Egg, Whole,
Cooked,
Fried
13.61g 13.61%
Egg, Whole,
Cooked,
Omelet
10.57g 10.57%

13. Types of Protein Present in Egg White and Egg
Yellow
Egg White
Egg white consists of about 90% water in which about
10% of proteins is dissolved.
Egg white is an alkaline solution which contains
approximately 40 different proteins.

14. Types of Proteins Present in
Egg White
- 54% Ovalbumin
- 12% Ovotransferrin
- 11% Ovomucoid

15. OVALBUMIN
Ovalbumin is an almost spherical glycophosphoprotein
which is the most common protein in egg white.
Storage protein
OVOTRANSFERRIN
Composed of 686 amino acids
Consists of 2 forms which contains neither phosphorus
nor sulfur
Disulfide crosslinks are present
Has antimicrobial and iron-binding ability

16. OVOMUCOID
Ovomucoid is a glycoprotein
Consists of 9 disulphide bonds
Has a stable spatial structure that it is not denatured
even upon boiling
TYPES OF PROTEINS PRESENT IN THE EGG
YOLK
The major proteins in egg yolk are lipoproteins
Livetin
Lipovitellin
Phosvitin

17. PHOSVITIN
A type of phosphoprotein
About 16% egg yolk proteins
Consists of about 10% phosphorus
Has iron and calcium binding
capacity

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