This Patch Can Detect Bacteria in Packaged Foods

This Patch Can Detect Bacteria in Packaged Foods

Wouldn’t be great if you knew definitively whether that meat you purchased at the grocery store is safe to eat? Or if it’s finally time to throw out that milk carton you’ve been trying to get every last drop out of?

While best before labels are helpful, they don’t tell shoppers if the product is contaminated with bacteria like E. coli or salmonella; it can take days to test for an outbreak in a lab, too.

To solve that problem, a team of researchers from McMaster University in Hamilton, Ont. have come up with an innovative way to detect harmful pathogens immediately.

A team led by Tohid Didar, an assistant professor of mechanical engineering, along with a group headed by Carlos Filipe, the chair of the school’s chemical engineering department, and biochemist Yingfu Li collaborated to create a transparent test patch called the “Sentinel Wrap.”

The researchers print particular molecules that can recognize the presence of certain bacteria onto a patch, which can be attached to food packaging, explains Didar.


“Part of the whole packaging could contain those molecules that we print,” he said.

Lead author Hanie Yousefi, a graduate student and research assistant in McMaster’s Faculty of Engineering, says the thin patch will have molecule sensors on one side to detect bacteria when it’s installed in food packaging; the patch has no effect on the food inside.

The patch is scanned by a handheld device, like a cellphone, in a grocery store to see if there’s bacteria present, says Didar.

“The beauty here is that you don’t need to open the packaging [to test it]” he said. “We wanted to have a system where you can find out on the spot, in real time.”

The research team is hopeful the technology can one day replace best before stamps on packages.

Related: Would Logo-Free, Plain Packaging Deter You From Junk Food?

 “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,” Yousefi said.

They went on to note that mass production of the patch would be cheap and simple, seeing as the molecules used to detect the bacteria can be printed onto any test material.

“This is quite innovative compared to previous work where you always had to analyze it [in the lab]” Didar said. “We’re really excited about it.”

Photo Credit: Prostock-studio/; Adisa/

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