by Tim Steury | © Washington State University
Judging by his occasional ribald references to the potato, Shakespeare considered the exotic tuber primarily as an aphrodisiac. Although the time of the potato’s introduction to Europe from the New World is not clear, recent scholarship has determined that the potato was grown in Spain as early as 1570. But the potato is an odd vegetable. Potatoes of that era were not uniformly oblong and smooth, but came in many colors and shapes, with odd protuberances that reminded some of, well, body parts. Although Indians had eaten them for thousands of years, Europeans were mystified, if not titillated.
But they got more adventurous. And the shifting socio-economic scene in Europe created demand for a reliable food crop, which the potato provided as it gained acceptance. According to John Reader in his recent Potato: A History of the Propitious Esculent, by 1622, Dr. Tobias Venner, a noted advocate of healthy living, had added to Shakespeare’s virtues additional nutritional ones: “they…doe wonderfully comfort, nourish and strengthen the bodies, ...
“...and [are a food that] incites to Venus,” he adds.
And you wondered why the average American eats over 140 pounds of potatoes per year?
Although the potato’s libidinous qualities have been neither proved nor disproved since Venner’s day, we have made substantial progress in understanding its nutritional qualities. And the news keeps getting better.
USDA potato breeder Charles Brown’s lab at WSU’s Irrigated Agriculture Research and Extension Center in Prosser was the first to discover antioxidants among the many other nutrients of the potato. Brown, who has worked with potatoes for 30 years, concentrates on breeding specialty potatoes, deeply colored varieties, from blue to deep purple and red, for their color-related compounds.
In fact, the deeper the color, the more nutritious the potato, it seems—at least in terms of antioxidants. Oxidation is one of those unfortunate facts of life. Metabolic processes in the body, as well as pollution and other environmental factors, produce very reactive atoms called “free radicals,” which damage the body’s DNA, providing an opening for the development of disease. Antioxidants, as the name implies, counteract those free radicals.
Probably less than one percent of the potato’s genetic diversity has been incorporated in modern cultivars, says USDA biochemist Roy Navarre, who is also stationed at Prosser. The potential for traits that might be gleaned from wild varieties is tremendous, particularly regarding phytonutrients, including antioxidants. There are many cultivars that have never been tested for their nutrients, says Navarre.
The newest edition of the World Catalogue of Potato Varieties, published by the International Potato Center (CIP) in Peru contains more than 4,500 potato varieties that are cultivated in over 100 countries worldwide. The catalogue also describes about 1,900 wild potato accessions from the wild potato collection maintained in the CIP genebank.
Closer to home, baby potatoes are particularly high in phytonutrients, says Navarre.
Fifteen miles outside of Prosser, Ed Schneider ’77 leads me down a row of deep green potato plants, a row that seems to stretch to the horizon. He pulls a plant from the ground to show me the baby potatoes that he’ll start harvesting in just a few weeks, just after July 4.
Right now they’re the size of large marbles. He describes how they will be coated with flavoring, then roasted and frozen.
It’s noon and my mouth’s watering. Unfortunately, the only places you can get these baby potatoes is on one of the airlines or from the big yellow Schwan’s trucks that cruise the rural United States.
Or you can grow them yourself. They’re actually a regular potato, he says, a Bintje, with bright yellow flesh. They’re just harvested early. The novel approach seems to be working, as the market is growing rapidly, says Schneider.
Even the plain old potato is good for you, says Schneider, who farms 1900 acres, mostly potatoes and sweet corn. A potato has more potassium than a banana, he says, echoing radio ads from the Washington State Potato Commission. As well he should. Schneider is a past president of the commission and is currently president of the National Potato Council.
According to the commission, Americans eat 147.8 pounds of potatoes per person annually. Washington does its part to feed that appetite. Second only to Idaho in potato production, Washington grows 20 percent of the potatoes in the United States. We’re the top producer of French fries. Eighty-seven percent of Washington potatoes are processed. One reason for the percentage is export, says Schneider. Raw potatoes are a living thing, and they grow in the dirt, he says, which makes them difficult to export due to disease worries. Fifty percent of Washington potatoes are exported, mostly to Asia.
Responding to the growth of area processors, Schneider’s father was just starting to grow potatoes when Ed graduated from WSU in 1977. Before that, he grew hay like many of his neighbors. But potato acreage has increased enormously since then. Potato acreage in the Columbia Basin has reached 160,000 acres. The dry climate (about six inches of rain per year) and readily available irrigation water provide an ideal environment for growing potatoes. Washington’s yields are among the highest in the world.
Besides his 400 acres of baby potatoes, the rest of Schneider’s potato acreage is devoted to the Ranger russet. The majority of potatoes grown in Washington are russets, and 80 percent of the total crop goes to French fries. Whereas he sends his crop straight to the processor, as do many of the farmers around Pasco, others do it differently.
According to post-harvest researcher Rick Knowles, about 60 percent of the Washington potato crop goes into storage, for later processing and fresh use. One of the major landmarks on State Route 26 near Othello is the enormous potato storage shed with Go Cougs painted on its sides. Owned by Johnson Agriprises (Orman Johnson ’69, president), the shed holds 18,000 tons of potatoes.
Keeping those potatoes in prime shape for French frying or other use is no small trick. They must be kept at a low enough temperature to keep them from sprouting. But if the temperature is too low, the potato’s starch starts turning to sugar. When the sugary potatoes are fried, the sugars combine with amino acids and turn brown. The taste is fine, says Knowles. His father, for one, likes them that way.
But the general consumer is put off by brown fries—or at least the industry believes so. And perception is everything. So the holy grail of French fries is a cultivar that stores under low temperatures without producing sugars.
If that potato is the grail, Knowles and Mark Pavek are Knights of the Round Potato Table. The potato court is the Tri-State Potato Breeding Program, made up of researchers from the USDA (including Brown and Navarre), the University of Idaho, Oregon State University, and WSU.
Breeders in the program make crosses toward desirable traits. The best material is selected, propagated, and evaluated. Pavek is responsible for the in-season evaluation, and Knowles is responsible for the post-harvest evaluation. Everything from the program, with the different growing locations and growing conditions, is sent to Pullman for evaluation under Washington growing conditions. Potato breeding is a long process. From initial cross to releasing a commercial cultivar takes about 14 years.
Besides evaluation, Knowles and his lab conduct basic research, including development of sprout inhibitors. One of their major finds is that the chemical that produces the smell from new-mown grass functions well as an inhibitor.
Another major effort of Knowles’s lab is how seed potatoes are handled. Potatoes do produce actual seed, which form a seed ball. The seed is not only very toxic, it is also very variable. Plant the seeds from a single potato plant, and you’ll get that many variations.
So potatoes are reproduced clonally. Each eye on a potato will produce a plant genetically identical to the parent. Varying storage conditions result in variations in yield.
The enormous diversity of the potato as well as the variety of preparation might well on their own have provided researchers plenty of work. But now they’ve been handed an additional challenge. McDonald’s, the largest seller of French fries, responded to shareholder pressure this spring by announcing it would survey its suppliers regarding pesticide use, with the goal of moving toward a more sustainable supply.
Despite their ancient Andean origins and great genetic diversity, domestic potatoes are one of our most vulnerable crops. Producing a perfect French fry requires protecting potatoes against a wide assortment of insects and diseases, which generally means the judicious use of pesticides and fungicides.
The move by McDonald’s will likely produce a newly energized effort by researchers toward exploring not only alternative controls for protecting the potato crop, but a closer look at the 99 percent of the potato’s genetic material remaining to be explored.
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