Lasers Zap Toxic French Fries

AUTUM C. PYLANT, NEWS EDITOR, autum.pylant@photonics.com

“Lasers and french fries” doesn’t have the same ring as “hamburgers and french fries,” or even “ketchup and french fries,” but the strange combination could make the fast food a little safer when it hits the plate.

Using NIR lasers, Lien Smeesters, a researcher from the B-PHOT Brussels Photonics Team at the University of Brussels, has developed a new laser system that scans peeled potatoes in the factory to detect toxic cancer-causing compounds such as acrylamide.

French fries being sorted and scanned with lasers. Courtesy of Photonics21.

For potatoes, frying causes the highest acrylamide formation. Roasting and baking causes less, and boiling or microwaving whole potatoes with the skin on does not create the cancer-causing compound. Yet despite the risks, “fried” french fries and chips remain quite popular.

Smeesters has teamed up with Tomra Sorting Solutions NV — a pioneer in optical food sorting machines — to employ her new sensor that scans peeled raw potatoes, weeding out the ones that do cause high levels of the toxic chemical when fried.

She told Photonics Media that her device works by scanning free-falling potatoes from the front and back with a laser that uses spatially resolved spectroscopy — a noninvasive, infrared imaging technique.

“The acrylamide precursors, including water, starch and reducing sugars, influence the spectral characteristics in the NIR part of the spectrum,” said Smeesters.

When the laser beam hits a potato, the light is immediately scattered. A “bad potato” produces a deviating internal scattering signal and is immediately knocked into a reject bin.

Close-up of illumination laser path that scans the potatoes. Courtesy of Photonics21.

Prior to this, food safety measures involved a person testing a sample and either accepting or rejecting an entire batch based on the results. Smeesters’ device tests every potato or individual french fry rapidly and safely within fractions of a second.

“Not all potatoes result in excessive acrylamide formation during frying. We have sought to spot the undesirable potatoes when they are in their raw, peeled stage,” she said.

Smeester has filed a patent for her detection method and the device will soon be integrated into one of Tomra’s industrial sorting machines to detect and discard offending food items. She hopes to one day introduce her product to the family kitchen.

“Although we are a long way off this yet, the miniaturization of the technology would enable a compact potato quality test tool in your home,” she said. “A handheld device indicating whether a potato would be unsuited for frying could reduce our exposure to acrylamide.”

For Smeesters, her research to “improv[e] food safety with optical screening” has given her the chance to hone her skills while giving back.

“This research gave me the opportunity to expand my expertise in optical spectroscopy and optical design while enabling me to work on a socially relevant research topic with industrial impact.”

Her research and laser that zaps toxic potatoes could one day make toxic food a thing of the past.