Grading, quality control and storing of eggs

• It facilitates packing, uniformity and pricing
• It improves the profit margin
• It aids in reducing wastage
• It facilitates quality assurance to customers

There are two grades of eggs based on quality of the eggs i.e. grade A and B. Out of these two grades there are 4 classes according to the sizes and weight. Quality is determined either of the two ways.

Interior quality

Candling eggs which can be done either by use of a candling torch or other machines to see the interior quality of eggs, is carried out in determining the quality of eggs. If the egg is good all light will pass through and the egg will look transparent and yellow. On the other hand if the egg is defective various observations are made:

• The egg has a very big air sac meaning the egg is undergoing deformities
• The egg has cracks
• The egg has weak spots on the shell
• Abnormal shell
• The yolk or albumin is very weak

Weight

There are various weights observed in eggs. Good eggs have weight ranging from 34 to 60g or more. When candling look at the interior quality of the egg especially the air sac and yolk, the soundness of the shell whether there are cracks; and stages in embryonic development for fertilized eggs. As an embryo develops, the air sacs also develop. Good quality eggs have an air sac approximately 4mm in depth. 

Grade A

Grade	Weight in grams	Shell	Air sac	White albumin	Yolk
A – Extra large	60g and above	Clean Unbroken Sound and normal shape	Up to 4mm in depth Regular	Clear and reasonably formed	Fairly well centered Free from defects Indistinct outline
A – Large	53 – 59g
A – Medium	45 – 52g
A – Small	38 – 44g
Not for commercial purposes	Less than 38g

Grade B

Grade	Weight in grams	Shell	Air sac	White albumin	Yolk
B – Extra large	60g and above	Clean Moderately stained Slightly abnormal shape	Up to 8mm in depth Slightly bubby	Clear but slightly weak	Slightly off centered Slightly visible outline
B – Large	53 – 59g
B – Medium	45 – 52g
B – Small	38 – 44g
Not for commercial purposes	Less than 38g

Eggs from hatcheries should not be kept for more than 10 days.

Storing eggs

About 56% of eggs are laid in the morning between 9 to 11am. To reduce damage, these eggs should be collected 3 times a day. The important considerations in storing eggs are:

• Infertile eggs keep longer than fertile eggs. Changes in temperature can trigger the embryo of fertilized eggs to start developing and if the temperatures fluctuate the embryo may die thus causing the egg to rot.
• De-fertilization of eggs can be done by immersing the eggs in hot water at 57.2 to 62.7^oC for 15 minutes or 15 days in hot weather. This temperature kills germinal disc. Another method of de-fertilization is to dip in lime water or warm coconut oil at the mentioned temperatures. In a sterile environment these eggs can keep for 3 months.
• Cooling of eggs. Eggs are laid at temperatures of 40^oC. Cool the eggs to 21^oC immediately after collecting by keeping in storage rooms with air conditioners. You can use wet curtains on walls or wet straws on the roof to bring the room temperature down.
• To keep eggs frozen separate the albumen and yolk and freeze them separately.
• The albumen and yolk can be dried separately, stored and packed then sold in supermarkets. These frozen or dried products can be used for making bread and other confectionaries.