STOKESLEY, England - Refrigerated trucks trundle down the country lanes laden with pale, doughy masses of fungus - 32 tons or more a day.
"Pure mycoprotein - good enough to eat, won't taste of anything, very bland," declares manufacturing manager Pete Willis, tearing off a golf ball-size sample from a 2,000-pound glob.
Workers in white boots shepherd the fungal paste through a sea of vats and clanking machines that mix, press, slice and dice the raw dough.
What comes out at the end is a matter of perspective - luscious artificial meat patties that taste just like moist chicken, or dangerous vat-grown "vomit-burgers" that are sickening consumers from coast to coast.
The product is Quorn, a fungus-based meat substitute that millions of Europeans have eaten for years. It entered the U.S. market in 2002 to rave reviews by consumers, but was quickly met with a dogged anti-Quorn campaign by an influential consumer group, the Center for Science in the Public Interest.
Michael Jacobson, CSPI's executive director, claims that Quorn, which he derisively terms an "odious" "mold"-based product, makes people ill - and he wants every last nugget expunged from American soil.
He has started a "Quorn complaints" Web site, published anti-Quorn letters in medical journals and petitioned the Food and Drug Administration to yank the product, which he likes to note is made by a former subsidiary of the "pharmaceutical juggernaut AstraZeneca."
"It seems in the FDA's eyes severe vomiting, diarrhea and anaphylactic reactions do not constitute harm," Jacobson said. "I think that's pathetic."
Quorn's manufacturers, based in the bucolic Yorkshire town of Stokesley, say they are perplexed and not a little irked over the complaints about what they prefer to describe as their "mushroom"-related product.
More than 1 billion servings of Quorn's 100-plus dishes have been eaten in Europe since the first savory pie was rolled out with pomp in 1985. Consumers have chowed down on Chinese-style char-grilled mini-fillets, beef-style casserole with herb dumplings and Southern-style Quorn burgers - all with no known deaths.
Several leading allergy experts say there is no evidence suggesting special problems with Quorn, although a few people can be expected to react badly to the fungus, just as some might to any other foodstuff, such as raspberries, milk or corn.
"We wouldn't be the No. 1 best-selling [meat substitute] in the U.K. and Europe if we had the kinds of reactions that Michael Jacobson is claiming," said Nick Hughes, managing director of Quorn's maker, Marlow Foods Ltd.
So far, Quorn is winning the fight. More than 6 million servings have been sold in the United States, the brand is the No. 1-selling poultry alternative in American health food stores, and its nuggets are the overall best-selling fake meat, according to SPINS, a natural food market researcher.
But Jacobson is used to a fight. After all, he's the man who helped get warning labels on foods containing the fat substitute Olestra with a relentless media campaign and battled to require food companies to display the trans-fat content of their products on nutrition labels.
There's more at stake than just another meatless patty. For the CSPI, it's part of a broad battle over the soul and safety of modern food, pitting the wholesomeness of Mother Nature against the corrupting power of big business and biotechnology.
"Quorn is about as far from natural as you can get," Jacobson recently wrote. "There is an abundance of healthful meat alternatives made with things that come from farms, like soybeans, mushrooms, rice. ... If you're going to sell a food that comes from a lab, a test tube, or a giant vat, it should at least not make so many people sick."
Quorn is made from a fungus known as Fusarium venenatum that consists of tiny translucent strands. The fibers' thickness and their branching patterns give Quorn a springiness and mouth feel similar to animal muscle.
"Delish!" said 40-year-old vegetarian Heidi Johnson of La Crescenta, Calif., who relishes the $3.99-a-box Quorn nuggets. "I don't eat many meat substitute products. ... Most of them taste awful or have a really disgusting consistency."
"We took to it, you know," said Billy Port, a burly 52-year-old Yorkshire taxi driver, who likes the chicken-style pieces in stir-fry dishes. And "I like my meat as much as anyone else."
When Quorn finally arrived in the United States, health food fans - and even Jacobson's group - embraced its chicken-y taste.
"Darn good tasting," the center raved in its newsletter. "A new dead ringer for poultry."
But a chill wind soon blew down the aisles of the whole-food stores.
It started with what Quorn executives now describe as the "mushroom controversy."
Curious about the new food, Jacobson noticed on Quorn's sunny orange packages that the product was made of mycoprotein from "an unassuming member of the mushroom family."