Breaking News on Food Safety & Quality Control

News > Industry news

Read more breaking news



Intelligent film changes colour to indicate spoiled food - Fraunhofer

By Rory Harrington , 04-Apr-2011
Last updated on 08-Apr-2011 at 13:02 GMT2011-04-08T13:02:06Z

Intelligent sensor - yellow good, blue bad

Intelligent sensor - yellow good, blue bad

The Fraunhofer Institute has developed a cost-effective colour-changing intelligent sensor film that can be integrated into meat or fish packaging to indicate if the food has spoiled.

The technology is much less expensive than alternatives such as electronic sensors and cost effective enough to allow broad take up, it claimed.

Experts from the Germany-based institute said the sensor film responds to biogenic amines produced by foods. These are molecules emitted principally by meat and fish when they decay and are responsible for the unpleasant smell given off by rotting foods, explained scientists from the body.

Colour changing

If amines are released into the air within the packaging, the indicator dye on the sensor film reacts with them and changes colour from yellow to blue.

“Once a certain concentration range is reached, the colour change is clearly visible and assumes the task of warning the consumer,” said Dr Anna Hezinger, from the institute’s Modular Solid State Technologies EMFT in Munich.

The technology can be used not just to shown when food is inedible - but can also serve as a warning to consumers who are sensitive to or intolerant of the presence of amines. The project has been sponsored by the German Federal Ministry of Education and Research.

The Fraunhofer said drivers for embarking on the research included the difficulties in assessing food quality from its appearance alone combined with uncertainties surrounding ‘best before’ dates.

“Scandals involving the sale of rotten meat have added to the uncertainty, and the customer [sic] may be shortening the shelf life through improper storage,” said the Fraunhofer, which added the sensor would help remove that uncertainty.

Cost effective and safe

“Unlike the expiration date, the information on the sensor film is not based on an estimate but on an actual control of the food itself,” Hezinger said.

A further advantage of the system is that it is “very inexpensive” – which will help its take up on a broad scale, said the body. Alternative solutions, such as electronic sensors, “would lead to a steep increase in the price of packaged meat”, claimed the Fraunhofer.

The sensor is still in development and doesn't have full EU/FDA food contact approval status, although the institute has embarked uponmigration studies, said Hezinger, adding they were searching for industrial partners for a pre-commercial development.


“Food safety is ensured by a barrier layer between the sensor film and the product itself. This barrier is only permeable to gaseous amines. The indicator chemicals cannot pass through,” added Hezinger.

Key Industry Events


Access all events listing

Our events, Shows & Conferences...