Egg quality control

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Questions and Answers

What happens to most eggs after they are laid?

They become contaminated with manure or other foreign material after laying.

What shape is preferred for eggs to be placed in Grades AA or A?

Elliptical

Why are rough-shelled eggs not preferred?

Because they break more easily

What are 'Body checks' in eggs?

Eggs with shells that have been cracked during shell calcification in the hen and have a layer of calcium deposited over the crack(s) before the egg is laid. Signup and view all the answers

What size of eggs are in Grade B?

Too small or too big eggs Signup and view all the answers

What is the preferred shell color for eggs?

Color does not play any role on the egg quality, nutritive value, flavor, or cooking characteristics Signup and view all the answers

What is the impact of round eggs and unusually long eggs on transportation?

They are much more likely to be broken during transportation Signup and view all the answers

Why are unusual shaped eggs not placed in Grades AA or A?

They have poor appearance and do not fit well in cartons Signup and view all the answers

What is the texture of a normal egg shell?

Smooth Signup and view all the answers

What is the composition of the eggshell?

The eggshell is made almost entirely of calcium carbonate (CaCO3) Signup and view all the answers

What role does color play in the quality of eggs?

Color does not play any role on the egg quality, nutritive value, flavor, or cooking characteristics Signup and view all the answers

What are chalazae and how do they indicate the freshness of an egg?

Chalazae are opaque fibrous structures that hold the yolk in the centre of the egg. The more prominent the chalazae, the fresher the egg. Signup and view all the answers

What is the function of lecithin in the yolk?

Lecithin is an effective emulsifier. Signup and view all the answers

What are the primary proteins found in egg white and their respective percentages?

a. Ovalbumin (54%), b. Ovotransferrin (conalbumin) (12%), c. Ovomucoid (11%), d. Ovomucin (2%) Signup and view all the answers

What minerals are present in eggs and in what form are they present?

Iron, phosphorus, calcium, copper, iodine, magnesium, manganese, potassium, sodium, zinc, chloride, sulphur; present as organic chelates in the edible part of the egg Signup and view all the answers

What is the role of xanthophylls in the egg yolk?

Xanthophylls (lutein, zeaxanthin, cryptoxanthin) are responsible for the yellow color of the yolk. Signup and view all the answers

What are the major fat components of egg yolk?

a. Triacylglycerols (66%), b. Phospholipid (28%), c. Cholesterol (5%) Signup and view all the answers

What percentage of the egg's energy comes from the yolk?

About 80% Signup and view all the answers

Which vitamins are particularly high in eggs?

Vitamins A, D, and B12 Signup and view all the answers

What percentage of the egg consists of the yolk?

32% Signup and view all the answers

Why food are packaged

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Study Notes

Egg Formation

The yolk of the egg is the matured ovum formed in the ovary of the poultry.
Ovulation occurs 30-60 minutes after the laying of the previous egg.
The ovum is surrounded by the vitelline membrane and takes 25 hours to form:
- 1 hour: Vitelline membrane produces.
- 4 hours: Albumen is secreted around the yolk in the magnum.
- 1 hour: Inner and outer shell membranes are formed in the isthmus.
- 19 hours: Shell is formed in the uterus.
Pigments may be added to make the shell brown.

Physico-Chemical Properties of Egg

An egg consists of approximately 10% shell, 58% white, and 32% yolk.
The color of the shell and yolk does not affect the egg's nutritive value.
About 80% of energy comes from the yolk.
Egg protein is of high quality and easily digestible.
Almost all fat in the egg is found in the yolk and is easily digested.

Vitamins and Minerals

Eggs contain every vitamin except vitamin C.
They are particularly high in vitamins A, D, and B12, and also contain B1 and riboflavin.
Eggs are a good source of iron, phosphorus, and supply calcium, copper, iodine, magnesium, manganese, potassium, sodium, zinc, chloride, and sulphur.

Egg Enzymes

The egg contains a significant quantity of enzymes, including protease, lipase, and lysosyme.
Lysosyme is located in the albumen layer and inhibits the development of Gram + bacteria.

Egg Structure

Egg White (Albumen)

Several proteins have been identified in egg white, including:
- Ovalbumin (54% of protein in egg white)
- Ovotransferrin (conalbumin) (12%)
- Ovomucoid (11%)
- Ovomucin (2%) accounts for the egg white viscosity
Other proteins include flavoprotein and avidin.

Egg Yolk

Major fat components:
- Triacylglycerols (66%)
- Phospholipid (28%)
- Cholesterol (5%)
Protein components:
- Livetin (LDL)
- Phosvitin
- Lipovitellins (HDL)
Xanthophylls (lutein, zeaxanthin, cryptoxanthin) are responsible for the yellow color.
Yolk is also a source of lecithin, an effective emulsifier.

Egg Shell

Made almost entirely of calcium carbonate (CaCO3).
Covered with many tiny pores.
A semi-permeable membrane that allows air and moisture to pass through.
Has a thin outermost coating called the cuticle that helps keep out bacteria and dust.

Inner and Outer Membranes

Transparent protein membranes that provide efficient defense against bacterial invasion.
Made partly of the protein keratin (also found in human hair).

Air Cell of Eggs

Forms when the contents of the egg cool and contract after the egg is laid.
Air space grows larger as the egg gets older.

Chalazae

Opaque fibrous structures that extend to the white, holding the yolk in the center of the egg.
The more prominent the chalazae are, the fresher the egg.
During aging, the chalazae lose their firmness and the yolk floats up.

Routes of Contamination

[Not specified]

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Description

This quiz covers the composition and structure of eggs, including the components of the yolk, the properties of the eggshell, and the role of lecithin. Test your knowledge on the physical attributes and chemical composition of eggs.