High tech food labels that turn 'bumpy' when products have gone off are set to be introduced by a dairy company to show high street shoppers when food is no longer safe to eat.

The scheme is being tested on dairy products by milk, cheese and cream giant Arla, which has developed labels which deteriorate at the same rate as the products it is used on.

When the product has reached the end of its shelf life the gelatine-based gel in the label reacts to changes in the packaged food and temperature outside resulting in a molecular breakdown.

The packaging then develops bumps, making it easier for consumers to see and feel if food is no longer safe.

Food producers often err on the side of caution and include use-by dates that are often several days before the food goes off.

The bumpy packaging is designed to give consumers confidence that even when the use-by date has expired, the food is edible until the gelatin reacts and has been backed by campaigners as a new way to reduce unnecessary waste.