When it comes to packaged fish or meat, it becomes visually almost impossible to distinguish between fresh and inedible products. Researchers have now developed a sensor film that can be integrated into the package itself, where it takes over the role of quality control. And if the food has spoiled, it changes color. The sensor film developed by the Fraunhofer Research Institution for Modular Solid State Technologies (EMFT) in Munich can immediately give a light to warn of spoiled goods. EMFT developed the film in a project sponsored by the German Federal Ministry of Education and Research. The sensor film is integrated in the inside of the packaging, where it responds to biogenic amines. Amines are molecules produced when foods, particularly fish and meat, decay. They are also responsible for their unpleasant smell. If amines are released into the air within the packaging, the indicator dye on the sensor film reacts with them and changes its color from yellow to blue. "Once a certain concentration range is reached, the color change is clearly visible and assumes the task of warning the consumer," explains Dr. Anna Hezinger, a scientist at EMFT. "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." This is not only interesting when it comes to identifying foods that have become inedible, but also as a warning to people who are also extremely sensitive to the presence of certain amines. 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, in this system that is inexpensive. Other solutions-such as electronic sensors, for instance would lead to a steep increase in the price of packaged meat. Things that come in direct contact with food products must also meet high standards. Scientists are also working on a measurement module with a built-in sensor film. Employees in the food and packaging industries can use the module to test the freshness of food products directly. The device objectively analyses the color response while at the same time providing a more precise result than is possible with the human eye. This also permits an exact identification of intermediate shades of color. Hezinger and her team are currently looking for partners in industry with which to further develop and produce the sensor film and measurement module. Scottish researchers managed to create food packaging that changes color as soon as it identifies when a food is going bad. The packaging represents a "smart plastic" film developed at Glasgow's University of Strathclyde. The intelligent film is to be used together with modified atmosphere packing. The latter is a process that prolongs the life of food by replacing the air inside its packaging with nitrogen, carbon dioxide. The atmosphere packaging usually has inserted labels that show the level of freshness. According to the researchers, their plastic could be incorporated into the production of packaging, thus eliminating the need of making and inserting labels separately. "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," stated the lead researcher Prof. Andrew Mills. He added that the new packaging is expected to have "a direct and positive impact on the meat and seafood industries. The new packaging works by using a new type of freshness indicator. These indicators already exist but are expensive because they are usually labels inserted into the packaging. The team have developed a new form "intelligent plastic" indicator - they haven't said what it's made from - which they say can be inserted into existing packaging rather than being inserted separately, thereby reducing costs. The new intelligent packaging provides an unambiguous signal of whether a food is safe to eat or not by changing colour once the product goes past its use-by date. This, he says, could help clear confusion over best before and sell-by dates, thereby reducing food waste, and also improving food safety by highlighting when food isn't being stored properly. In other futuristic developments, interactive packaging that is able to ‘talk' back to consumers could be less than a decade away. Dr Ross Lee, a researcher at the Packaging & Technology Integrated Solutions in Maryland, US, told the Neutrons and Food Conference that the use of printable electronics in ‘smart' packaging was viable. Other emerging nanotechnologies include sensors and batteries as well as new scanning technologies. The use of these and printable electronics could help consumers and reduce costs and wastage. The research findings into a host of new smart packaging technologies are currently being examined with a view to further developments. Printable electronics refers to powered circuits emitting an electronic signal that can be printed cheaply onto packaging. Combined with the developments in smartphone technology, in particular, the trend towards geo-location based software applications; this could enable products on the shelves being able to communicate with shoppers' devices. This would allow people to see the exact in-store location of the product they seek, or be told if an item is out of stock. Other nanotech techniques currently planned include putting sensors into packaging which contain a dye that degrades in contact with food pathogens, alerting shoppers - through their devices, that the product has reached its use-by date. Another development is the inclusion in the packaging of an antimicrobial agent that could be triggered to help preserve food for longer.