All the samples were Australian-grown. The apples are kept in cold storage under controlled conditions from the time they are picked.

But scientists said that quality and freshness was being affected because they were being kept for longer in order to satisfy consumer demand for year-round products. Our apples were sent for testing at the independent Sydney Postharvest Laboratory, which conducts research for the fruit and vegetable industry. Analysis showed the Woolworths samples were about 10 months old while the Norton Street and Coles products had spent 9 months in storage since being harvested.

The apples were also tested for firmness and levels of ethylene, a natural plant hormone that stimulates fruit to ripen but can also cause it to go off. Stephen Morris, the principal research scientist who conducted the tests, said that Norton Street apples were of the best quality and Woolworths the worst.

Woolworths' apples had 75 times the ethylene levels of the fruit from Norton Street. Dr Morris said: "Apples can be kept for six months and they will still be of very good quality. "After nine months the quality is going to start to be affected and at 10 and 11 months you are not going to get such a good apple.

"If you want to eat fresh fruit now, don't buy apples, buy mangoes." Dr Morris said that any apples on sale at the moment would be at least eight months old.

Woolworths chief executive Michael Luscombe said: "Apples have a very short growing and harvest season and it has always been the case that they are picked and kept in cold storage. "The cold storage helps to slow the ripening process but of course it can't keep an apple as fresh as if it came straight off the tree so it will affect the quality. "Customers want apples all year round. We have a big commitment to Australian farmers and 97 per cent of all our produce is from Australian producers.

"The only options other than cold storage would be to not have apples all year round or to buy from the northern hemisphere where the quality might not be as good. "I accept that consumers might not be aware of the fact that the apples on sale are not fresh off the tree.

"It might be something that we need to do in terms of customer education, perhaps using our television adverts when we have staff members talking about what is in season to explain when they will have come from cold storage." A spokesman for Coles said: "The technology for storing apples is now very sophisticated." mfrith@sunherald.com.au