|The importance of the egg quality
As a natural product, all eggs are not equal and need to be
routinely checked for quality to meet the specifications being
increasingly demanded by today's quality conscious retailers.
Most retailers impose on their suppliers a specification that
all eggs should meet. This usually embraces a range of
quality characteristics, such as shell colour, Haugh unit (HU)
and yolk colour, as well as checks on packaging, bar codes,
print colours and eggs being packed correctly, with the
labels placed in the correct position.
One of the primary egg quality traits most frequently
measured is albumen quality. Measured in millimetres (the
higher the reading the better the quality). This measurement
is a very efficient method of determining the quality and
freshness of eggs.
The albumen thins as an egg ages because the protein in
the eggs changes in character over time. - that's why fresh
eggs sit up tall and firm and why stale or older eggs spread
out and run all over a flat surface when they are broken out.
The Haugh unit
In the 1930's, an American researcher, Dr R R Haugh,
introduced a formula that is still used internationally as the
definitive method of defining true egg quality and freshness.
This formula takes into account egg weight in grams and
albumen height in millimetres and provides - rounded up to
whole numbers - a range of HU values from single figures in
extremely poor quality eggs to over 100 plus in very good quality
The HU calculation is commercially essential where eggs from
different flocks and of different sizes/ages/breeds are tested.
Please click here for a guide to quality by HU.
Haugh unit rating Quality of eggs
*It is at this Haugh unit value when the albumen begins to spread and
consumer resistance begins to start. At 50 and below, there is often a
reluctance to again purchase eggs for a period of time irrespective of
Haugh unit versus air cell
Whilst in many countries the air cell is still used as the statutory
measurement to define the age of an egg, it should not be
regarded as a method of guaranteeing egg quality - it is often
possible to have an air cell within legal tolerances yet have the
HU in the poor/unacceptable categories.
This is why many retailers have been very specific in writing into
their product specifications HU levels usually in excess of 70.
The air cell height increases with age through loss of moisture.
However long before the air cell reaches the point where the
egg changes its quality grade, the true consumer quality can
already have deteriorated. The speed of deterioration is
dramatically affected by the storage temperature and age of the
||Consumer resistance point *
Good Egg quality
Albumen height gauge