IT can lead to your fridge becoming a biohazard and costs UK families around £11 billion a year in waste – but now a Scottish inventor has solved the problem of jars of food festering unnoticed by creating a "smart" label that tells you when it is time they went in the bin.

Edinburgh-based Pete Higgins has scooped a £50,000 prize to develop his Use Within label (UWI), which counts down the days a jar stays fresh and turns red when its contents are no longer palatable.

He won the Barclays 2011 Take One Small Step competition with his idea and will now be given cash to develop his invention and put it into the shops.

He said: “I came up with the idea one day when I was feeding my son and I reached for a jar of mayonnaise which said ‘eat within four weeks of opening’.

“I realised I had no idea how fresh it was and set about thinking how I could come up with something which would let me know.

“The idea was simple, but it took a lot of work to figure out a way to make it a reality.”

Now at the prototype stage, the label uses a chemical reaction which is activated when the jar is opened and displays how long it will stay fresh with a series of small green squares.

When the final one is reached, the label turns red -- meaning that the food within is no longer safe to eat.

To work out how to make label function, Mr Higgins sought the help of Dr Will Shu, a lecturer at Edinburgh’s Heriot-Watt University, to collaborate on the scientific development and overall design of the UWI label, with the goal of it becoming a standard feature on every food jar throughout the world.

More than £11bn worth of food -- or £680 per family -- is wasted every year in the UK, much of it thrown out while still edible and safe to consume. Mr Higgins hopes his system could have a significant impact on both the amount of food being unnecessarily discarded and the money people spend on their shopping.

It could also have other uses -- such as ensuring medical supplies with a limited shelf life are not used by accident.

He added: “My initial aim was to help to reduce the amount of food wasted each year, save people money and minimise the risk of illness, but I am now keen to investigate how it can be used for other products such as blood transfusion bags, veterinary and pharmaceutical products, industrial glues and sealants and even cosmetics -- in fact, anything with a critical shelf life once it has been opened.”

Having already attracted around £50,000 in investment and developed a working model, the prize will go towards funding a way to mass-market the label to sell to manufacturers.

Dr Shu, an academic at the School of Engineering and Physical Sciences, said: “It has taken Pete over three years to develop this product and we have been working with him for the past 18 months to bring it to its final stage. The results have exceeded our expectations.

“I am delighted to have been involved in what has been a highly exciting journey and look forward to continuing to work with Pete to develop the device further for use in other products and move into other business sectors.”