You’re familiar with package labels that tell you to “eat this food by” [fill in the date]. These expiration dates printed on packaged goods are useful for letting us know the optimal day by which food should be consumed. There is, however, widespread consensus that these instructions are conservative. Items can often be safely eaten long after the recommended date.
A precise system that tells when food is spoiled and should be disposed of for safety reasons — as opposed to a modest estimate driven by manufacturers’ needs to sell more product — would be more useful.
Conservationists are rightfully intrigued by technological developments that promise to do just that. Scientists are working to develop packaging that actually tells when food has gone past the point when it can be safely eaten. How does it work? Plastic wrapping can be manufactured that contains a photonic gel. A gel that will change color when exposed to chemicals associated with foodstuff rotting. In tests, researchers were able to demonstrate that the color of the plastic could be changed depending on a wide variety of substances with which it comes into contact. A refrigerated package that turns from clear to red tells the consumer all they need to know.
Using plastic film that changes color when the food it encases shows a characteristic of spoilage sounds like science fiction, but the future of preservation is here.