CORVALLIS, Ore. - Despite all the concerns about global warming, it makes sense that there have to be a few effects that aren't all bad, and scientists at Oregon State University have identified one of them - nature's aromatic miracle, the truffle.
Truffles, some of which are so prized in cooking that they can sell for up to $1,500 a pound, favor the type of hotter, drier forest habitats that may expand as the planet warms. Their production and even evolution of new species could increase, experts say.
In the meantime, researchers are still working to identify the full scope of ecological roles that these unusual fungal specimens play. James Trappe, a faculty member in OSU's Department of Forest Ecosystems and Society, has been at the task for 55 years now, has co-written three books on truffles in the past three years, and still is learning more about their complex value to forest ecosystems.
"I first came upon these odd fungal bodies when I was studying forest soils and tree root structure in 1955, and it turned out they were truffles," Trappe said. "Since then I've published journal articles on more than 150 new species, but there are hundreds more we still don't know about. All truffles are probably edible, but of the estimated 6,000 species, only a couple dozen are actually used in cooking."
The truffle, like a mushroom, is the fruit of a fungus, but with one essential difference - it grows underground. That protects it from heat, frost and winds, but makes spore distribution a problem. So over millions of years truffles evolved with one remarkable distinction to help them reproduce. Mature truffles produce odors, often intense to the human nose. Others produce compounds that humans can't detect but other animals can. Animals locate truffles by their smell, dig them up, eat them, and spread their spores far and wide when they defecate.
"Pigs love to eat truffles, dogs can smell them from 30 feet away, and a flying squirrel can smell them from the air, glide down and land right on top of one," Trappe said. "Their aromas don't always smell good to humans. One Australian truffle species smells like dog feces - the dogs and little marsupials just love that, but it's not much use for cooking."
That intense smell, when it's a good one, has been the key to truffles' use in gourmet dining. Sliced thin and usually cooked very little or served raw, they can be used in many dishes, melted with butter, or add flavor to salads. Trappe makes a favorite pasta dish with the Oregon white truffle, which has a cheesy, garlic, pungent aroma, and goes quite nicely with a light cream sauce and a little parmesan cheese.
The most desired truffles are difficult to find, and even harder to cultivate. European harvests are declining, not expanding. One of Trappe's former graduate students is now the leading truffle grower in the United States, and the demand for his products exceeds the supply. It takes four or five years to produce a crop and the soil characteristics have to be carefully controlled.
That scarcity drives up the price. A giant Italian white truffle, prized for its intense flavor, was dug up in Tuscany in 2007, weighed more than three pounds, and fetched $330,000 at a global auction. And truffles have been sought around the world for a long time; they were favored by Egyptian pharaohs and ancient Romans, and hunted for generations by Australian Aborigines, nomadic Arabs and the Kalahari Bushmen.
Cost and culinary characteristics aside, truffles also play essential roles in forest ecosystems, in particular around woody plants such as Douglas-fir, pine, oaks, willows, filberts, hazelnuts, eucalypts, and some other tree species. They form one type of absorptive root system called mycorrhiza that helps provide plants with nutrients essential to their survival.
Truffles evolved more than 50 million years ago and are found around the world, but are most diverse in the Mediterranean region, western North America and Australia. Cool, rainy winters and warm, dry summers - like in Oregon - make them especially predominant. They are an important food source for many animal species, from the red-backed vole in the United States to the long-footed potoroo in Australia, a marsupial whose diet is 95 percent truffles. In the Pacific Northwest, they are a key source of food for the northern flying squirrel, which in turn is a favored prey of an endangered species, the northern spotted owl.
Trappe and his colleagues wrote about many of these issues in a 2008 book published by Rutgers University Press: "Trees, Truffles and Beasts: How Forests Function." In a previous book, they provided a field guide to hunting, identifying and enjoying truffles.
"We're still learning new things about these remarkable fungi," Trappe said. "I've sent some truffle samples to the National Institute for Natural Products Research for testing. Some strongly suppressed tuberculosis bacteria, and others showed anti-inflammatory effects. And we're continuing to learn about their ecological roles."
On the other hand, one old custom of using pigs to help hunt these hidden, underground gems is changing. The pigs are great at sniffing and rooting out truffles. But dogs are now a more preferred assistant, because the pigs - being pigs, after all - often insist on eating the truffles they find.
At more than $1,000 a pound, that isn't cost effective.
Click photos to see a full-size version. Right click and save image to download.
Jim Trappe, 541-750-7278