Most of us are familiar with the practice of checking the use-by dates on food packaging labels. It turns out that many customers throw away the food by those dates, even though in many cases the food is still safe to eat.
Researchers at Imperial College in London hope to change that practice. They have developed paper-based electrical gas sensors, called PEGS, which can detect spoilage gases like ammonia and trimethylamine in meat and fish products—items consumers are particularly leery of using past the use-by date. The prototype sensors cost two U.S. cents to make and can be read by smartphones, enabling users to easily check the packaging to see if the food is still safe to eat.
The researchers made the PEGS sensors by printing carbon electrodes onto readily available cellulose paper. As the biodegradable materials are eco-friendly and nontoxic, they will not harm the environment and are safe to use in food packaging. The sensors are combined with near-field communication (NFC) tags to allow them to be read by mobile devices.
Laboratory tests with the sensors on packaged fish and chicken uncovered trace amounts of spoilage gases quickly and more accurately than existing sensors, at a lower cost.
The researchers believe the sensors can provide food retailers with a more reliable, lower-cost alternative to use-by dates. “Although they’re designed to keep us safe, use-by dates can lead to edible food being thrown away,” says Dr. Firat Güder of Imperial’s Department of Bioengineering and the study’s lead author. “In fact, use-by dates are not completely reliable in terms of safety as people often get sick from foodborne diseases due to poor storage, even when an item is within its use-by.”