Determination of specific gravity of eggs

What Is Specific Gravity?

Specific gravity is a measure of density relative to the density of a reference substance. The reference material could be anything, but the most common reference is pure water. If a material has a specific gravity less than 1, it will float on water.

Specific gravity is often abbreviated as sp gr. Specific gravity is also called relative density and is expressed by the formula:

Specific Gravitysubstance = ρsubstance/ρreference

Theory

    A fresh egg has a density between 1.03-1.1 g/mL, which means it will float in a solution that has a density greater than or equal to 1.03-1.1 g/mL. (The density of pure water is an even 1.0 g/mL.) Thus, an egg placed in must or wort having a specific gravity greater than approximately 1.030 to 1.100 will float. The denser the liquid, the higher the egg will bob in the solution. 

    Fresh eggs will have higher specific gravity than old and long stored eggs, because there will be a loss of moisture in the old eggs which inturn replaced by air.
    So the air cell will become bigger as the egg is stored for a longer time.
    Similarly, eggs having stronger shell will have higher specific gravity than thin shelled eggs.

    This gives an indication of the eggshell quality, as well as its freshness.

A normal egg will have a specific gravity of 1.06.

• Any value less than this may indicate that the egg is old, or the eggs are thin shelled; irrespective of other criteria, smaller eggs will have high specific gravity due to more uniform shell.
• By knowing the egg weight and volume.

The measure of specific gravity can be made by several methods.

• • By measuring the egg weight and then weighing the egg in water, to find the weight loss in water.
  • By dipping the eggs in a salt solution having several concentrations of salt dissolved in it: having a specific gravity ranging from 1.0-1.1 with an interval of 0.02. 

Specific gravity = Weight of the egg in gram / Volume in cc