How to boil an egg - made easy

The age-old argument over the best way to cook the perfect boiled egg could be a thing of the past thanks to a new hi-tech ink logo going on shells.

After cooking begins, an invisible, temperature-sensitive thermochromic print appears in black to indicate when an egg is soft, medium or hard-boiled.

The eggs, developed by UK assurance scheme Lion Quality, will be sold in three different types of cartons.

The new logos will start to appear on eggs in the next few months.

"We had a lot of inquiries from people which sparked an interest in the industry," said a spokeswoman for Lion Quality.

"We said OK, this is a big issue - people can't even boil an egg."

The best technique has taxed some of the greatest culinary experts in the past.

In a 2005 survey conducted by the magazine Waitrose Food Illustrated, five leading chefs all came up with different solutions.

And in 1998, a TV series presented by Delia Smith included one show concentrating on the finer points of boiling an egg.

Smith said her How To Cook programme on the BBC intended to re-introduce people to the pleasures of cooking and herald a return to basic skills.