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Electrons stop spuds sprouting

September 10, 2004 By Mark Peplow This article courtesy of Nature News.

Treatment could replace chemical sprays to keep potatoes fresh longer.

There are few sights in the kitchen so woeful as a vegetable rack filled with sprouting potatoes. The white nodules that grow from a potato's eyes are not only unsightly, they seem to suck the very flavour out of a spud.

But Japanese researchers have a solution. A quick dose of low-energy electrons stops potatoes sprouting for up to four months, even if they are stored at room temperature. The researchers used a Van der Graaf generator to deliver a beam of electrons to potatoes moving along a conveyor belt. The electron beam works by preventing cell division within the sprout bud tissue, similar to the way that radiotherapy stops cancer cells multiplying.

Setsuko Todoriki and Toru Hayashi, food scientists at the National Food Research Institute in Ibaraki, Japan, say their method could replace the potentially harmful chemical sprays and expensive radiation treatments that are currently used to stem the surging sprouts.

Sprouting is one of the biggest problems when storing potatoes
Norah Olsen
Idaho Centre for Potato Research and Education, Twin Falls
"Sprouting is one of the biggest problems when storing potatoes," says Norah Olsen, a potato expert from the Idaho Center for Potato Research and Education, Twin Falls. "I think this is a fantastic development."

Chemical reactions

Untreated potatoes in the Japanese experiment started to sprout after 60 days. Lower temperatures reduce sprouting, but they also increase the sugar content of the potato. When deep-fried, this sugar caramelizes, giving fries a nasty brown colour that turns consumers off. Todoriki and Hayashi's method keeps sugar levels down.

In Europe and North America, potato producers often use chemical sprout inhibitors such as chloropropham, also known as CIPC. But residues of this slightly toxic chemical can linger on a potato's skin, worrying consumers and regulatory bodies alike.

"We recognized some years ago that CIPC was a problem for us and the industry," says Alan Wilson, an agronomist for UK supermarket chain Waitrose. "Consumers have made it quite clear that they don't want chemical residues in their food."

Japan already bars its potato producers from using chemicals on their spuds. For the past 30 years, its potatoes have instead been blasted with gamma radiation in a special facility in Hikkedo, Japan, which treats more than 100,000 tons of potatoes annually. But the process is expensive and requires hefty shielding to protect workers.

Todoriki and Hayashi say that their low-energy electrons are cheap to generate and do not need thick safety shielding to protect spud handlers, allowing much more cost-effective production lines.

Wilson thinks the method may have promise outside Japan, but is ultimately wary of technological fixes. "It depends how it's interpreted by consumer groups - they might see it as radiation," he says.


  1. Todoriki S. & Hayashi T. J. Sci. Food Agric., doi:10.1002/jsfa.1906 (2004).


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