Bad food? New sensors will show with a glow

Food packaging with these patches could help people avoid potentially sickening germs

Is this chicken safe to eat? New glowing sensors built into food packaging might soon alert cooks to risky food.

Kwangmoozaa/istockphoto

Sensors in packaging could someday warn you about tainted food in time to keep you from eating it. The plastic patches could detect bacteria that might poison diners.

Carlos Filipe is a chemical engineer at McMaster University in Hamilton, Canada. He and his team developed the new sensors. To make them, the researchers coated a flexible film in molecules that glow in the presence of E. coli. These bacteria are usually harmless. But certain strains of this species can seriously sicken people. A leading source of exposure to those bacteria? Food.

This new sensor glows around molecules that E. coli cells produce. So the material doesn’t have to directly touch the germs to know if they’re there.

The sensors give off what’s known as fluorescence. They take in energy at one wavelength and emit it as a glow at another wavelength. You can’t see that glow under normal light. You have to shine an ultraviolet lamp or a fluorescence scanner to detect it.

The new sensors are about the size of postage stamps. The researchers tested these plastic patches on meat and apple juice hosting E. coli. The sensors lit up brightly. But when the sensors were touching untainted food samples, they didn’t glow. Filipe’s team described its new sensors online April 6 in ACS Nano.

Other scientists have developed tools to detect fluorescence that can attach to a smartphone. These devices are only the size of a matchbox. People could use them to check packaged food at home before opening it, Filipe says. If the food sensor was glowing, a person would know the food was unsafe. Grocery stores could also provide scanners so customers could check a food before buying it.

Next up, the McMaster group plans to make films that glow near other dangerous bacteria, says Tohid Didar. He is a mechanical engineer on the team. One of those bacteria might be Salmonella, which can cause fever, cramps or diarrhea.

Foodborne illnesses such as Salmonella and E. coli kill some 420,000 people worldwide each year, according to the World Health Organization. But food packaging with built-in microbe monitors might warn people of tainted foods so that they can steer clear of them.

Maria Temming is the staff reporter for physical sciences, covering everything from chemistry to computer science and cosmology. She has bachelor's degrees in physics and English, and a master's in science writing.

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