The Impossible Burger is coming to Burger King as the Impossible Whopper, in a market test that could lead to the largest restaurant industry embrace yet of a plant-based meat substitute.

The Impossible Whopper will feature the same bun, cheese and condiments as a traditional Whopper, but with Impossible's plant-based patty where animal meat is normally found. Fifty-nine Burger King stores in the St. Louis area will offer it as of April 1, with a potential expansion to the other 7,100 US restaurants later in the year.

While the partnership is debuting on April Fools' Day, it's no joke. Burger King is making an unusually high-profile endorsement of plant-based meat, while Impossible is facing its own Tesla Model 3 moment in terms of going mainstream.  

I got a jump on the debut when I arrived at Impossible's Silicon Valley headquarters carrying two bags of Whoppers from the local Burger King. There, J. Michael Melton, Impossible's technical sales and culinary manager, cooked up a batch of the patties they're supplying to Burger King, using the same broiler Burger King uses. He swapped them in for the beef in the Whoppers (with professional dexterity that somehow left the burgers appealing) and I took a couple bites. 

The remarkable thing was how unremarkable they were: Nothing gives away the fact that this Whopper contains a different main ingredient.

The patties supplied to Burger King will be based on Impossible's new 2.0 formulation that was announced at CES in January, 2019. Among other upgrades, this formulation holds up better in restaurant environments like hot holding trays or the 6-inch drop at the end of the conveyor that grills the patty for exactly 2 minutes and 35 seconds at 630 degrees.

"We're making meat from plants. That's never been done before," Impossible Foods founder Pat Brown told me, tacitly demoting competitor Beyond Meat's plant-based burger. "People have made plant-based replacements for meat, but they haven't made plant-based meat."

One way the Impossible Whopper will indeed differ from the original is price, costing a significant dollar more in an industry where brands have gone to war brandishing menus of items that only cost a dollar. As with electric cars, price parity with the established choice is a future linchpin to mainstream success.

"Once we have products that taste the same or better and that cost less, plant-based and clean meat will simply take over," according to Bruce Friedrich, executive director of the Good Food Institute, which champions plant- and cell-based meats. "So very little will change in people's everyday lives as more and more meat is produced either from plants or from cells. Consumers will continue to buy burgers, chicken sandwiches, and sausages (but) those products will simply not have the adverse impact on our environment and global health."

Burger King doesn't break out sales figures for Whoppers, let alone its expectations for the more expensive Impossible Whopper, but some insights can be inferred from a 2018 survey by Faunalytics. Assuming price was no different between beef and alternative burgers, 65 percent of consumers polled said they would still stick with beef, 21 percent would choose a plant-based burger like Impossible, and 11 percent would select a cultured burger grown from animal cells, which isn't expected on the market until the early 2020s.

But Impossible's Pat Brown feels such surveys leave out the qualitative experience. "If you give them our burger, and then ask them the question again, a very large majority of them say they would definitely buy it and would be willing to pay a premium for it."

Acceptance of plant-based meats turns not only on taste, texture and price but on overcoming momentum. Environmental and animal welfare arguments have triggered a million conversations and social media posts about meat's issues, yet US per capita meat consumption hit an all-time high in 2018.

A recent consumer survey also found that concern for personal health handily trumped concern about the environment and animals as a driver of plant-based meat choice. "We need to change the meat, because we aren't going to change human nature," Friedrich said in a recent New York Times profile.

Launching the Impossible Whopper in Missouri, rather than in one of California's crunchy kale enclaves, is jumping right in, given that Missouri is the first state to make it a crime to use the word "meat" to label a product that "is not derived from harvested production livestock or poultry," with up to a $1,000 fine and a year in prison. But the 62-year-old "Whopper" brand is sufficiently synonymous with beefiness that the Impossible version should communicate meatiness without having to use the m-word.

The biggest shoe yet to drop is, of course, McDonald's. With nearly four times the US sales of No. 2 Burger King, few restaurant brands coin more mainstream food trends, yet McDonald's has eschewed both Impossible and Beyond burgers. Instead it offers its own McVegan burger in Finland and Sweden, and the Vegetable Deluxe in the UK. Neither sandwich would likely be mistaken for a hamburger.

And while burgers are the American diet icon, steaks aren't far behind, and an even bigger challenge in alternative meat marketing may soon unfold at fast casual steak chains like Outback or Texas Roadhouse. Unlike burgers, steaks generally arrive on the plate unadorned, without bun, cheese or condiments to mask any shortcomings. Get steak right, so the thinking goes, and the plant-based dominoes begin to fall.

Impossible's Brown says burger R&D has prepared it for the challenge. "I can say, with complete confidence, that we're going to nail it and not only make a great steak, but we're going to make a steak that's as good as anything that ever fell out of a cow."