Poultry Gallery - Eggs
Eggs are one of the most nutritionally-rich natural foods you can eat.
An egg consists of a yolk at the centre surrounded by albumen (white) enclosed by a shell. The yolk consists of fats, vitamins and minerals, together with about half of the egg's total protein content. A transparent barrier, called the vitalline membrane, surrounds the yolk and prevents it from leaking into the albumen. Inside the yolk is the germ cell (or germinal disc). This is the site of the cell division if the egg is fertile.
The colour of the yolk varies, and this factor is influenced by the laying hen's diet. It will be the brightest orange if there is a lot of grass, green vegetables or maize meal in the feed. Hens that free-range on grass in spring and summer will lay eggs with a darker yolk than when ranging in winter, when the grass has stopped growing. Some layers mash and pellets will contain a yolk enhancer, such as canthaxathin.
Egg albumen is rich in protein and vitamins, and contains substances to protect the egg from micro-organism which may have entered though the shell. Eggs are one of the few foods to naturally contain Vitamin D.
A fresh egg placed in a bowl of water will sink to the bottom and lie on its side. An older egg will sink and stand up on one end and, if it is really old, it will float completely. As the air cell increases with age, it affects the buoyancy of the egg, causing it to float. The deterioration of an eggis due to an increase in the size of the air sac, combined with evaporation from the white and yolk. When broken, the yolk of a fresh egg will sit up and the white will appear thick around the yolk. An older egg has a flatter yolk, with a runny, watery white.
Standard Hens Egg Sizes
- Very Large 73 g and over
- Large 63-73 g
- Medium 53-63 g
- Small 53 g and under