A material that changes colour when exposed to oxygen could be used to indicate whether packaged food is still fresh, its inventors claim.

Scientists from Canada have developed a new, smart oxygen sensor that could indicate food freshness in packaging. J C Scaiano and colleagues from the University of Ottawa developed their sensor using a liquid reagent, 2-(hydroxymethyl) anthraquinone, whose reaction with oxygen showed a short lived colour change in solution. To make the colour change more permanent, the team trapped the sensor molecule in a zeolite - a porous inorganic solid. Using the zeolite (the faujasite NaY) produced a solid matrix that could be easily manipulated and developed into a sensor.

The team believe that this compound could have a range of applications including food packaging in supermarkets. 'Other applications may include laboratory glove boxes and other instrumentation normally required to operate under oxygen-free conditions,' says Scaiano. They also hope that this will be developed into a commercial product.

Michele Zgraggen