Student develops laser scanner for potato inspection

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Amid growing concern about the discovery of cancer-causing chemicals in crisps and French fries, Lien Smeesters from the University of Brussels has developed a spatially-resolved spectroscopic sensor that can inspect peeled potatoes in the factory to detect toxic compounds and prevent them from reaching the consumer. 

Lien Smeesters was a recipient of the Photonics21 Student Innovation Award, which was presented at the association’s AGM in March in Brussels

Earlier this year, the Food Standards Agency (FSA) issued warnings about eating over-fried potatoes, burnt toast and crisps that can contain cancer-causing chemicals such as acrylamide, deeming them a serious health threat to billions of consumers.

At present, raw potatoes that produce an excess of the carcinogenic chemical acrylamide cannot be detected in a fast, sensitive, and non-destructive way.

‘When frying potatoes, acrylamide formation is one of the biggest concerns of the potato-processing agriculture industry. At present, raw potatoes that produce an excess of acrylamide cannot be detected in a fast, sensitive and non-destructive way,’ explained Smeesters. 

This new technique developed by Smeesters, 28, in collaboration with Tomra Sorting Solutions, employs a new sensor that scans peeled potatoes, weeding out food that may cause high levels of the toxic chemical.

It works by scanning food items, such as potatoes, from both the front and back with a laser that employs spatially resolved spectroscopy.

When the laser beam hits a potato, part of the light will be internally scatted during interaction with the tissue. A bad potato produces a deviating internal scattering signal, owing to the high acrylamide precursors.

This unwanted food item is spotted in mid-air as it begins to fall. Selected by the internal processor, the potato is then ‘knocked out’ of the batch by being blasted with a stream of air and into a reject bin before it hits the conveyor belt below.

The sensor is able to do this with each and every individual potato scanning and rejecting in milliseconds. 

‘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. After scanning with laser beams, the good potatoes will emit a different light signal than the unsuited ones leading to an unambiguous detection,’ Dr Smeesters explained.

Having filed a patent describing the use of this detection method, the laser scanner will be integrated into one of Tomra’s industrial in-line sorting machines, detecting and discarding food items that may contain excessive acrylamide precursors.

Several tons of products could be examined per hour to look for these carcinogenic compounds without using dyes or chemical additives, and without damaging or even touching the food.

Smeesters’ development comes at a time where tougher acrylamide regulation has been called for by the sustainability group ‘Changing Markets Foundation’ as well as the recent ‘Go for Gold’ campaign by the Food Standards Agency, helping people understand how to minimize exposure to acrylamide when cooking at home.

‘With so many products containing worrying levels of acrylamide above the EU Indicative Value guidelines, we had to take action. This research and collaboration will hopefully provide unprecedented levels of food safety for millions,’ Smeesters said.