A Choice investigation has revealed some unsettling information regarding the freshness and quality of eggs across Australia.

Choice has discovered that when it comes to buying eggs what you see is not necessarily what you get and people who pay extra for eggs deemed to be free-range, free from antibiotics and hormones, may be misled by such marketing.

Choice researchers tested eggs sold at Coles and Safeway stores in Melbourne, Sydney, Perth and Brisbane.

They found that 36% of the 700 free-range, barn-laid and cage eggs tested were "weak and watery", and fell below an international benchmark for quality and freshness called a Haugh test and furthermore, tests results revealed there was little difference in freshness between free-range, cage and barn-laid eggs.

Choice says free range eggs may evoke a romantic idea of happy 'chooks' roaming in lush green paddocks when in fact half the free-range eggs sold in Australia are produced on an industrial scale and some come from flocks of up to 120,000 birds.

These hens often live in huge sheds and may never access the outdoors and their eggs come off conveyor belts.

Although more than a third of the eggs were deemed stale, Choice says this was an improvement on a 2004 test, which revealed that 53% of free-range eggs had failed to meet standards.

Choice says barn-laid eggs, provided they are certified by the RSPCA, meet humane standards, while claims that eggs are free from antibiotics and hormones mean very little.

It seems that hormones ceased being used in chicken and egg production in the 1960s but cage birds are routinely given antibiotics for disease prevention, previous research however has claimed that these antibiotics do not enter the eggs.

The other option of course is to buy certified organic eggs - Choice says check the labels - or go to smaller local shops or markets to find eggs with independent free-range certification.

Choice says as far as cholesterol is concerned, eggs have it in the yolk, but still earn a healthy Heart Foundation tick as they are highly nutritious and can be an important part of a healthy diet.

Some eggs are enriched with omega-3 fatty acids by feeding the hens a special diet - omega-3 fatty acids are good for the heart and may improve brain development.

Choice says cracked or broken eggs are risky and should be thrown out as they can be contaminated with bacteria such as salmonella.

Choice says the problem with the freshness relates to refrigeration and while eggs are often refrigerated during transportation, when they arrive in supermarkets they are placed on shelves and experts suggest that one day on a shelf is the equivalent of keeping the eggs in the fridge for a week.

The industry is dominated by three big producers, Novo, Pace Farm and Manning Valley, who account for well over half the free-range eggs sold in Australia and Choice says consumers buying free-range eggs because they believe in animal welfare, may find the brands in the big supermarkets may not actual meet their expectations.