Scientists test potatoes’ chip potential


UNIVERSITY PARK, Pa. — At Penn State, thousands of potato varieties from around the globe are put through extensive cross-breeding programs, genetic research and intercollegiate collaborations.

But once a year, the university’s potato researchers switch from pipettes, computers and other high-tech equipment to potato peelers, slicers and a deep fryer. It’s potato-chipping time.

For a few days, research technicians head for Building C at Penn State’s Russell E. Larson Agricultural Research Center at Rock Springs to fry and rate potato chips. They test four potato cultivars at a time, taking eight slices from the center of each to fry them in commercial fryers.


Laying out 16 separate piles on a table, the researchers meticulously evaluate the chips with a 10-stage, light-to-dark visual rating chart that shows the chips’ levels of darkness immediately after frying.

Barbara Christ, head of the plant pathology department, who oversees the potato research program and annual chipping process (and serves as hands-on member of the chipping crew), said there’s plenty of tasting, but the potatoes aren’t being rated for flavor.

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Up to 240 varieties are being rated for appearance only, as researchers find out which spuds can be turned into pale-golden, crispy chips after four months in cold storage.

From exotically colored imports to table-quality tubers, each is evaluated for chip-worthiness. That’s appropriate, she explained, because while many researchers and commercial outfits are growing and developing hundreds of potato varieties, not many places actually give them the chip test.

Chip test

“We’re actually one of a very few programs that does chip processing,” Christ said.

“The University of Maine and Penn State are the only two on the East Coast that do as much chip processing, and I think we do much more than most across the country.”

Along with the University of Maine, Christ gets potatoes from the U.S. Department of Agriculture’s Beltsville, Md., development facility, from Cornell University and from commercial concerns across the country.

“There were many one-room, mom-and-pop chip companies that would sell at certain times of the year. But we’ve lost potato growers across the state due to land prices.”
Barbara Christ
head of the Penn State plant pathology department

“We get seed from Minnesota, Michigan, North Dakota, and Idaho,” she said. “We’ve tried some red and blue chips, but usually we’re using white- and yellow-fleshed varieties.”


And there are regional differences about what makes a “good” chip.

Midwesterners prefer a lighter, milder chip while Easterners like a stronger-flavored, darker chip and the Northeast states and Canada favor salt- and vinegar-flavored chips.

Christ and her team assemble an extensive report on clone performance and herbicide and fungicide trials that is made available to Extension educators as well as to growers through the Pennsylvania Department of Agriculture’s potato research board.

She said the information is especially valuable as the state’s potato production declines.

“Historically, a lot of chip companies originated in Pennsylvania,” she said. “There were many one-room, mom-and-pop chip companies that would sell at certain times of the year. But we’ve lost potato growers across the state due to land prices.

Shrinking acreage

“Twenty years ago, York County was one of the biggest, but that’s all developed now with very little agricultural land, and growers that are left are specializing in higher-value crops.”

While Pennsylvania ranks only 13th in total potato output ($40 million annually), the Keystone State is the No. 1 source of chipping potatoes. About 70 percent of its production is chipping potatoes, which account for about one-quarter of U.S. chipping potatoes, the highest in the nation.

The U.S. Department of Agriculture estimates there are about 92 chip-production plants nationwide; Pennsylvania has the most, with 24, according to that state’s agriculture department. Pennsylvania turns out about $57 million worth of potato chips annually, according to state agriculture department sources.

But Pennsylvania continues to slip in national potato rankings as production moves west.

Nebraska, Wisconsin, Michigan, and Minnesota, all have passed Pennsylvania recently in acreage.

“When I arrived at Penn State in 1984, the state had 25,000 acres of potatoes,” Christ said.

Production costs

“We’re down to 14,000 acres now. Another factor is that potatoes produced on the East Coast suffer with more climate-related foliar diseases and more insect problems, so our cost of production is higher. Our soil types are so variable that quality out of a single field can fluctuate, whereas in Idaho, production tends to be more uniform.”

Such challenges are Christ’s motivation for temporarily putting aside her lab’s molecular work identifying genetic markers and sequencing genes to work with a deep fryer and piles of chips. In addition to being fun, it fills a valuable function.

“My grandfather grew potatoes, and there’s a lot of basic research not understood by growers,” she related.

“I always understood the science, and I took the time and effort to work with the growers, so I could understand their needs and interests. Now, I can tell them in layman’s terms what it takes to get where they want to go next season, and I can help them understand that some things take 20 years.”

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