Clever plastics indicate off food

Packaging that changes colour to alert consumers when food is starting to go off is being developed by scientists at the University of Strathclyde.

Central to the project – which aims to improve food safety and cut unnecessary food waste – is a new type of indicator made of ‘intelligent plastics’ which change colour when food is about to go off.

“The intelligent plastics are made of a polymer film with colour-changing particles (intelligent pigments) embedded in them,” project leader Professor Andrew Mills told Laboratory News. “When food goes off it emits volatile agents which will change the colour of the particles in the film.”

The indicator will be used in modified atmosphere packaging which keeps food in specially-created conditions to prolong its shelf life. Freshness indicators typically take the form of labels inserted in a package, but Mills and colleagues are hoping to create an indicator which is an integral part of the packaging.

“Modified atmosphere packaging is being used increasingly to contain the growth of organisms which spoil food but the costs of the labels currently used with it are substantial,” Mills said. “We are aiming to eliminate this cost with new plastics for the packaging industry.”

By giving a clear and unambiguous sign that food is beginning to perish, the indicators could resolve the potential confusion about ‘best before’ and ‘sell-by’ dates, and highlight the need for food to be stored in properly sealed refrigerators.

“We hope that this will reduce the risk of people eating food which is no longer fit for consumption and help prevent unnecessary waste of food,” Mills said. “We also hope it will have a direct and positive impact on the meat and seafood industries.”

The project – which received £325,000 in support from the Scottish Enterprise Proof of Concept Programme – has another 15 months to run, but Professor Mills hope to see a commercial product emerge within two years.