This transparent patch can detect harmful bacteria in food.
Credit: McMaster University

If you’ve ever sniffed a carton of milk or stared at a piece of chicken in the fridge trying to determine if it’s safe to eat—we have good news for you. After all, foodborne bacteria result in around 600 million illnesses yearly, 420 thousand of them leading to death, according to the World Health Organization.

Sure, manufacturers offer "best by" and expiration dates to give consumers a ballpark idea of when to toss their food, but they're only estimates. Now there’s something even better.

A team of researchers at McMaster University developed a transparent patch that can be added to food packaging to test for harmful bacteria, such as E. coli and Salmonella. The research is published in ACS Nano, and the results have the team convinced the patch could be an accurate and cheap alternative to estimated dates stamps on packaged foods.

"In the future, if you go to a store and you want to be sure the meat you're buying is safe at any point before you use it, you'll have a much more reliable way than the expiration date," says lead author Hanie Yousefi, a graduate student and research assistant in McMaster's Faculty of Engineering.

One side of the clear rectangle contains droplets of molecules that can detect for certain bacteria. When the sensor comes in contact with a food product, a handheld device like a smartphone can scan the package to indicate if there is bacteria present. The sensor has no negative effect on the food itself.

Though the primary potential use for the product is for preventing foodborne illness, researchers say the sensor could also be used to test bandages for infections in wounds or to determine if hospital equipment is sterile.