If making impostor eggs for use in mayo and muffins is a challenge, creating fake meat that actually feels and tastes like muscle is a much harder one, as anyone who has eaten a seitan sandwich can attest. Herbert Stone, former president of the Institute of Food Technologists and a member of the first Apollo space mission's food science team, remembers encountering this dilemma around 1963, when the price of beef was skyrocketing and he began helping companies develop soy-based extenders. Since then, Stone says that he has consulted for three or four fake-meat companies and has seen 15 or 20 (he won't say which ones) whose products have failed over the years. Current clients looking to perfect fake meat include several Chinese manufacturers.

The biggest challenge in making meat alternatives, Stone says, is that it's almost impossible to replicate the particular mix of protein and fat found in animal products. The fat in meat provides flavor, and heat from cooking changes the protein to create meat's distinctive texture. Soy protein, on the other hand, is fat free. Simply mixing it with, say, coconut oil, doesn't work—the bond between animal fats and proteins is notoriously difficult to replicate. "The problem always was that it didn't taste like a burger," Stone says. "When I would talk with companies about this, I'd ask: 'Why do you want to create an imitation and call it that? Why not just create a product and call it something else?'" But food marketers didn't want vegetable patties or soy croquettes—they wanted to sell burgers. "It was like banging your head against a concrete wall," Stone says. A product that is genuinely indistinguishable from meat, though, might be a different story—and Stone believes that Beyond Meat just might be able to pull it off. "They're smart people, I think; that's an opportunity," he says. "The big question is that they have to come up with a line of products that has appeal to the consumer. I think it's just the beginning."

The strips' flavor resembled that of a grilled Chick-fil-A breast abandoned in a cup holder for a few days. But that didn't stop me from finishing the whole 12-ounce package.

After sampling Beyond Meat's Southwest-style Chicken-Free Strips, I tended to agree with Stone's cautious optimism. They really did taste startlingly similar to what I remember from my pre-vegetarian days. There was a tissuelike resistance—I could tear off strands that felt like muscle. Granted, without any sauce or fixings, the strips' flavor resembled that of a grilled Chick-fil-A breast abandoned in a cup holder for a few days. But that didn't stop me from finishing the whole 12-ounce package.

The lifelike texture is the result of nearly a decade of tinkering at the University of Missouri, where Beyond Meat's lead researcher, Fu-hung Hsieh, found a way to put soy and pea proteins through an extruder to realign them into fleshlike strips. Like Beyond Eggs, the Beyond Meat team uses a combination of heating, cooling, and pressure to break the proteins' molecular bonds and put them back together, but the complex sequencing of that process is what Beyond Meat claims separates its products from dull fake-meat patties already on shelves.

"If you're comfortable with how bread is made, you'd be comfortable with how our product is made," Ethan Brown, Beyond Meat's founder and CEO, told me. But he wouldn't go into specifics about his company's energy balance sheet—this information, he said, is proprietary. That lack of transparency is part of why some foodies dismiss meat substitutes in favor of sustainably raised real meat. "I think it's a big can of worms," Will Turnage, a Brooklyn-based food app designer, told me. Turnage is the creator of Carv, an online platform that helps users figure out which farms, slaughterhouses, and packers their supermarket meat came from. The app took first prize last year at New York's Hack//Meat, a periodic event where tech types compete to find solutions to food problems. "What I worry about is, okay, we're going to create an egg substitute, and then 10 years down the road, we're going to realize there's some unknown effect," Turnage says. "It's an overly dramatic comparison, but—look at what happened with asbestos."

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True, there's a little more chemical complexity to the raw materials for fake eggs and meat than what goes into a loaf of bread. Commercial soy isolate, for example, is commonly produced by bathing soybeans in a chemical compound called hexane, whose emissions are a main component in smog. Soybean processing accounted for 42 percent of hexane emissions cataloged by the Environmental Protection Agency in 2011. Small amounts of hexane have also turned up on some soy products—a troubling finding, since it's a known carcinogen and neurotoxin. The Food and Drug Administration doesn't regulate hexane, and it's unclear how any residue might affect consumers, but there are other risks too: In 2003, for example, hexane was released during routine maintenance at an Iowa soybean plant. The resulting explosion killed two workers.

Tetrick's Hampton Creek Foods doesn't use soy in its egg products, but Beyond Meat lists it as a primary ingredient in its Chicken-Free Strips. "Hexane is not part of Beyond Meat's recipe or production process," Hilary Martin, a Beyond Meat spokeswoman, told me in an email. But Martin confirmed that Beyond Meat buys soy protein isolate from DuPont-owned Solae, whose Illinois plant released 281,000 pounds of airborne hexane in 2011, according to the EPA. Martin said that Solae provides Beyond Meat with data that shows no traces of hexane on the protein isolate. When I asked Brown whether he was concerned about hexane, he called the residue complaint "a red herring." He said he had never heard that it was an air pollutant but promised he'd look into it.

Brown's next potential project: a protein slab that tastes like fish and contains all its nutritional properties, but doesn't actually look like a fillet.

How much will consumers really want to know about how the fake sausage is made? We may soon find out. Last spring, the Founders Fund, one of the first venture capital firms to invest in Facebook, Napster, and Palantir, invested $1 million in Beyond Eggs—and in September, Whole Foods stores in Northern California began selling the fake mayo I tried. In early 2014, Beyond Meat's plant-based beef crumbles will make their supermarket debut. Though it won't divulge any details, Hampton Creek Foods says it is also working with Heinz (which wouldn't comment) and other Fortune 500 companies to roll out more products.

Of course, some food technologists are already thinking beyond Beyond Meat. NASA began investigating in vitro meat grown from turkey cells as early as 2001, and by 2008, PETA offered a $1 million reward to anyone who could produce chicken from a petri dish. Four years later, some 30 companies had entered the in vitro game. In August, using blood from fetal calves to nourish cow cells, a Dutch team finally succeeded in making the world's first lab burger—a two-year, $332,000 project funded by Google cofounder Sergey Brin. The live-streamed taste test aired on more than a thousand TV channels around the world. According to Chicago food critic Josh Schonwald, one of the three testers who sampled the burger, the texture was good but the taste was too lean. "I miss the fat," he said. Still, "the aim is to, of course, make a consumer product out of it," lead scientist Mark Post said in a promotional video. "It may take 10 years, maybe even earlier."

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Brown isn't worried about competition from lab-grown meat—not yet, at least. For now, he's focused on brainstorming new plant-based products. One idea: a protein slab that tastes like fish and contains all its nutritional properties, but doesn't actually look like a fillet. "Would that be interesting?" he asked me, seeming genuinely curious. "Or do you think we would perfectly have to mimic fish? Because we could do that."

Pure hubris? Maybe. But braggadocio is a job requirement for guys like Brown and Tetrick—even if their products aren't perfect yet, their pitches are. In his most impassioned speeches on fake meat, Brown often refers to the advent of the automobile: Cars were not another kind of horse-drawn carriage. "We're not trying to be an alternate to chicken," he says. "We're trying to be a new chicken."