Runny egg whites

Some farms have problems with watery egg whites and these often lead to customer complaints about 'stale' eggs. But watery or runny whites are not necessarily an indication that the eggs are old.

If an egg is broken onto a flat surface and the albumen (white) is watery and spreads-out, this may indicate that the egg is stale - but there can be other reasons. The height of the albumen and the weight of the egg are used to calculate a value in Haugh units on a scale of 0 to 110. Under this measuring system, the lower the value, the staler the egg is supposed to be.

A minimum Haugh unit measurement of 60 is desirable for whole eggs sold to domestic consumers.  Eggs leaving the farm should average between 75 and 85 Haugh units and many farms conduct random testing to ensure that this quality standard is met.

Although watery whites are thought to be mainly an indication of the increasing age of the egg, the problem can be exacerbated by high storage temperatures and low humidity. Also, as birds age, the Haugh unit value of their eggs decreases by about 1.5 to 2 units per month of lay. Some birds consistently produce eggs with watery whites (Haugh units less than 30) later in lay, which is one reason that most commercial farms only keep their birds for one laying season.

Here are some steps eggs farmers take to minimise the problems of watery whites:

Keep the flock age as low as possible;

Collect eggs several times each day and store at correct temperature – less than 20ºC;

Grade, pack and despatch eggs to customers as quickly as possible;

During grading, remove all eggs with rough, porous shells and/or large air cells;

Consider fitting a humidifier in the coolroom to maintain storage humidity at 70 - 80%;

Maintain good disease control, particularly with correct vaccinations;

Ensure there are no fungal toxins in feed (don't use wet or mouldy feed);

Eliminate rough handling;

Pack eggs on filler flats or in cartons with the air cell (blunt end) upwards.

Excluding disease, the single most important factor affecting the albumen quality of freshly laid eggs is the age of the birds. With advancing flock age, Haugh unit scores decrease and the variability of the scores increases. An induced pause in egg production (moult) can often restore albumen quality in aging hens. Both strain differences and strain/age interaction effects in Haugh unit scores of fresh eggs have often been observed, but these are normally small and have little practical significance. Albumen quality of the egg is not greatly influenced by bird nutrition. .

When ambient temperatures are high, delays in egg collection increase the rate of Haugh unit score decline. The maintenance of albumen quality during egg storage is dependent on the eggs being cooled quickly following lay and subsequently being held at low temperatures.

Different strains of hens can show a great variation in Haugh unit scores. Strains laying white-shelled eggs have been shown to be much less variable than those producing brown-shelled eggs.