Egg quality

Breaking strength

The stability of the egg shell is one of the most important quality parameters in a hen’s egg.

With our FEST device we offer you a quick and easy solution for the determination of the breaking strength.

The pure measuring time is 2 seconds for a single egg. Add to this the time required for inserting and removing the egg, and you can comfortably test up to 900 eggs per hour.


To determine the Haugh units, the egg is cracked on a flat glass plate after weighing.

The egg white height gauge is then used to determine the egg white height at a distance of approx. 1 cm from the edge of the yolk.

The formula for calculating the Haugh unit is:


  • HU = Haugh-unit
  • h = certain height of the albumens in millimeters
  • w = Mass of the ice in grams

The calculation is done automatically in our software.
Alternatively, you can read out the data from a table.

Yolk color

The color of the egg yolk is traditionally expressed in “Roche values” from 1 to 15.

The name “Roche” refers to the company Roche, which released the color fan shown below a few years ago. Roche was acquired by DSM Nutrition Products GmbH a few years ago.

Our measuring instruments work with an R-G-B sensor whose filter curves correspond to the human eye (3-range method). From the red, green and blue components we calculate the Lab* values from which we then determine the Roche value. In our software, both the Lab* values and the Roche values are stored.

Shell thickness

For the determination of the shell thickness we offer a special micrometer screw, where one measuring surface is rounded. This makes it possible to correctly determine the thickness of the concave (curved) eggshell. The device can be connected to a PC via our data collector.