Researchers have developed a transparent paper patch that lights up when it picks up pathogens in food. The device still needs regulatory approval, though.

You may not have to give that pork tenderloin the sniff test or decide if your ground beef is still good just by its color.

McMaster University engineers and researchers want to help you know immediately whether your dinner is still safe to eat.

They’re doing that with something quite ordinary: paper.

Researchers at the Canadian university wrote about their innovation in ACS Nano.

They reveal they’ve been working to develop paper-based detection systems for a variety of uses.

One such area is food-testing technology and it has given rise to what the researchers and developers are calling Sentinel Wrap.

These thin, transparent patches are printed with harmless DNA molecules, or biosensors.

The patches are affixed inside a package or container of food. They remain stable up to 14 days, which is typically long enough for perishable foods to be packaged, purchased, and cooked.

What’s more, you don’t have to open the package to read the biosensors. Instead, the sensors will turn a color when they detect harmful pathogens in certain foods, from meat to apple juice.

You can use a handheld device, such as a smartphone with specific software, to detect the signals from the patches.

“The patch has a fluorescent green dye,” Hanie Yousefi, a lead study author and a graduate student and research assistant in McMaster’s Faculty of Engineering, told Healthline. “When the bacteria are present, the DNA piece will start shining and you can measure the light by a smartphone or appropriate software.”

Currently, the patches are designed to detect two of the most common and most harmful foodborne pathogens, E. coli and Salmonella.

Each year, more than 48 million people in the United States become ill because of foodborne diseases, according to the Centers for Disease Control and Prevention. About 3,000 of those people die as a result of the pathogens.

Worldwide, the number is even higher with 600 million illnesses and 420,000 deaths. According to the World Health Organization, 30 percent of these deaths from foodborne illnesses are in children ages 5 and younger.

The McMaster researchers hope these patches can assure people that the food they have in their hands is safe to eat.

Likewise, a positive result could deter them from cooking with unsafe products.

Ultimately, Yousefi says, the patches could help replace the ubiquitous “best before” dates many manufacturers use on food products.

These dates, while a helpful prediction, aren’t always the best measure of a food’s state. Transportation and storage can impact how long a food is still good and safe to eat.

“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 says.

Each year, millions of tons of food are thrown away. Grocery stores are also forced to toss perfectly good meat, produce, and other foods because of these estimated dates.

“We can stop the waste of good food and have a smart way of examining the food,” Yousefi says.

Now that they’ve shown how effective these patches can be, Yousefi and the team of engineers and biochemists who developed Sentinel Wrap hope food industry partners will start to look for ways to incorporate the patches into their products.

They’re also looking to develop new patches that “target the foodborne pathogens that are actively harming people in the world,” she says.

However, before you’ll be shining lights on your pork loins and chicken thighs, Yousefi says the patch has to clear several regulatory hurdles.

They hope a partnership with food companies can help bring the product to widespread use more quickly.

“Having financial support from industry partners and investment can help move the process forward,” Yousefi says.

While they wait for these next phases, the researchers are already looking ahead to other areas where these pathogen-detecting strips might be useful.

The same technology, the researchers say, could be used to check for bacteria contamination on surfaces at hospitals, alert consumers to expired ingredients in other products such as medications, or detect infections in wounds.