CHAPINGO, Mexico — At this time of year, when corn grows high, some farmers go into their fields hoping that a disease has infected their crops.
They inspect for swollen husks, a telltale sign that a parasitic fungus has spread into a spongy iridescent mass inside the ears.
The farmers are pleased, for the fungus is one of the greatest delicacies of the Mexican kitchen. It's been called the Mexican truffle, and a "food of the gods." The unique, earthy taste has been part of local cuisine since Aztec times.
The name of the fungus in the indigenous Nahuatl language is huitlacoche (pronounced weet-la-KOH-chay, sort of rhyming with Don Quixote). As hard as that may be to say, it's infinitely sweeter sounding than the English name: corn smut. That moniker is a slur to huitlacoche's complex flavors and defamation of its culinary properties.
"It's completely different from other fungus. There are Ph.D.s here trying to figure out why its taste is so special," said Dr. Clemente Villanueva, a geneticist at the Autonomous University of Chapingo, a top agricultural school that's in the same valley as Mexico City.
The cultivation of huitlacoche is skyrocketing, as urban Mexicans are regaining an appreciation of foods native to their country. Once a haphazard if tasty infestation, huitlacoche now is being farmed commercially, with farmers injecting spores of the fungus into immature cornstalks. The fungus ruins the corn for human consumption, but it sells for much more than the corn itself, which can still be used to feed livestock. As a result, huitlacoche production has climbed fourfold in the past five years, Villanueva said.
"Before, it was seen as a food of the poor. Now it's the food of the rich," said Raul Nieto Angel, the dean of the crop sciences department at the university, which extensively tests and researches huitlacoche.
Chefs at swank restaurants are rekindling a traditional love for the fungus.
"It is very exquisite," said Rodrigo Flores, chef at the Hacienda de los Morales restaurant in Mexico City's upscale Polanco district. "Demand for it is rising every day. . . . In our restaurant, we consume 2 tons of it a year."
In recent decades — before huitlacoche really took off — the fungus largely was sauteed with garlic, onions and poblano chile strips and served by street vendors in quesadillas, folded-over corn tortillas. Then cooks realized its flavor would make nearly any dish sensational. Restaurants sometimes offer it with beef, fish, in crepes with chipotle sauce, with eggs, in cream soups or with shrimp.
"It is so rich in flavors," Flores said, "that it can become the central element in a main dinner."
Seen in the fields, huitlacoche makes one want to run and hide.
"It's this kind of puffy mushroom, a bluish-grayish color, that will kind of take over an ear of corn. It looks sort of alien and otherworldly when you actually see it," said Lesley Tellez, an American who writes a food blog and operates Eat Mexico, a business that offers culinary tours of the capital.
She described the taste as "mushrooms on steroids" but added: "It's not really like any other mushroom you've tasted. It's really unique."
Connoisseurs look for it fresh in markets when it's still spongy, rather than flaccid. They don't wash it before cooking, to avoid flushing away the succulent black spores.
Mexico's pre-Columbian inhabitants savored the fungus. But like chefs today, they struggled to classify it. The ancient Aztecs called it a mushroom, while the Maya put it in the same food category as meat. Some ancient peoples said it had curative properties for stomach ulcers.
What scientists have learned more recently is that the fungus is rich in lysine and tryptophan, the two key amino acids that most corn lacks. When eaten together with corn, it creates a more complete range of amino acids for protein synthesis, Villanueva said.
Huitlacoche is endemic to six states of central Mexico, where airborne or soil-borne spores infect the tender parts of the corn plant, taking anywhere from 12 days to nearly a month to mature, depending on climate and elevation.
Once harvested, farmers hurry the fungus to market.
"It is very perishable. It is as fragile as a strawberry," Villanueva said. "If you keep it at 4 degrees (Celsius, or 39 degrees Fahrenheit), it can keep for nine days."
Baskets piled with fungus surrounded Lilia Simon Bravo as she attended to clients at Mexico City's largest produce market, Central de Abastos. She ripped the husks off pregnant-looking corn, bloated by the huitlacoche, and said the taste of that produced in her native Puebla state was unrivaled.
"This has not been injected. It is natural," she said. "It is really excellent."
Agronomists have learned to use large syringes to inject a liquid rich with huitlacoche spores into immature corn, essentially seeding it. Under the right conditions, farmers can produce a ton or two of huitlacoche per acre. Villanueva said that in irrigated greenhouses, researchers got as much as 12 tons per acre.
Huitlacoche doesn't yet enjoy legal status as a special food. Unlike French Champagne and Camembert cheese, Italian prosciutto, Florida orange juice, Idaho potatoes and Vidalia onions, all of which enjoy some legal status requiring production within a limited geographic area, anyone who knows how can harvest and sell huitlacoche. This is a sore subject at the local university, where experts say Mexico fails to protect a culinary treasure.
Already, agronomists from Uruguay and the United States have inquired about huitlacoche production, and farmers near Morelia are shipping the fungus to Japan.
Canned huitlacoche is available in specialty and ethnic markets in the United States and many other countries but the taste, at best, is a shadow of the fresh stuff.
Even so, this reporter once attended a dinner in Beijing where the Mexican hostess offered chicken breast stuffed with huitlacoche, made with the canned variety, which she'd hand-carried from her homeland. It brought gasps of pleasure from exalted diners.
Tellez said foreign diners should overcome the "ick factor" of eating something with an unappetizing English name and give it a try as an exotic food.
"This is something that has existed in the Americas for so long. It's unique. It's different," she said. "It's something you'll only find in Mexico, and that gives it some cachet."
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