The competition between the nation’s two highest-profile plant-based burgers has escalated with the news that Impossible Foods has released a new, gluten-free version of its Impossible Burger, just six weeks after Beyond Meat premiered its newly redesigned Beyond Burger.

Like Apple does with its operating system, Beyond Meat and Impossible Foods are replacing their flagship burgers with updates, with every confidence that consumers will approve of the switch. Each company promises that its “version 2.0” — a term both use — tastes even more like real beef.

And as their markets expand, Impossible Foods and Beyond Meat are increasingly invading the territory each has claimed. The companies have flanked one another at every turn for years now, both comparing themselves to software companies rather than food manufacturers, both attracting hundreds of millions of dollars in investment as a result.

First to market was Beyond Meat, which Ethan Brown founded in Southern California in 2009. Since the release of its chicken strips made of pea protein in 2013, it has targeted the freezer and refrigerated shelves of grocery stores. In the summer of 2016, the company put much of its muscle into promoting a new flagship product: the Beyond Burger, which Whole Foods first agreed to sell in the fresh meat case. Safeway followed in May 2017.

Within a month of the Beyond Burger’s first public appearance, Impossible Foods, which former Stanford professor Pat Brown (no relation) started in 2011, released the first Impossible Burger at Nishi, one of David Chang’s New York restaurants. In October, it arrived on the West Coast at Jardiniere and Cockscomb in San Francisco. The embrace of chefs such as Chang, Jardiniere’s Traci Des Jardins and Cockscomb’s Chris Cosentino turned the “veggie burger that bleeds” into a hypebeast, drawing long lines of food obsessives both omnivorous and vegan.

Impossible Foods opened a large production facility in East Oakland in fall 2017 capable of producing 4 million pounds of the burger each month, and it says 5,000 restaurants around the country now sell Impossible Burgers, often at prices higher than their beef burgers. Among these are major chains like Cheesecake Factory and White Castle .

In the meantime, sales of all plant-based meats have exploded. According to Nielsen data commissioned by the Plant-Based Foods Association, from 2017 to 2018 plant-based meats saw a 24 percent growth in grocery sales, compared with just 6 percent from 2016 to 2017. “Overall, we’ve seen a raising of the bar in terms of quality,” said Michele Simon, executive director of the Plant Based Foods Association, a trade association Beyond Meat belongs to. “No longer does the consumer have to sacrifice to cut back on their animal meat consumption.”

Ethan Brown says Beyond Meat’s 2.0 burger has added mung bean protein to its core ingredients of pea protein and coconut fat for textural variety. But the real innovation is using biomedical equipment to rethink how those proteins, fats, and water are dispersed through throughout the patty. “The texture of meat is complex, and there’s a beauty to how unique it is,” he said. “How do we increase the heterogeneity of a bite so you’re getting the nuances of tendons and fat, fat bursting, different cuts of protein, bits of gristle?”

The Impossible Burger 2.0, which began a trial run at 120 restaurants starting Jan. 15 and will be universally available by April, has undergone a more radical change. According to senior flavor scientist Laura Kliman, the company switched from wheat to soy as the primary protein, making the burger gluten-free, and substituted cellulose for xantham and konjac gums as a binder. “What we focused on improving about the new recipe was taste (and) texture, and getting the product to have juiciness, which we never had before.”

Unchanged is the ingredient that gives Impossible Burger its meat-like flavor and ability to morph from pink to brown as it cooks: vegetable “heme,” which mimics the hemoglobin in blood. Heme is made by genetically engineering yeast cells to produce a protein found in the root of a soy plant (the yeast cells themselves are discarded). Impossible Foods applied to the U.S. Food and Drug Administration to add heme to its Generally Recognized As Safe list of food additives. The agency gave its final approval to heme as a flavoring agent in July 2018. Now Impossible Foods awaits a second FDA approval, for using heme as a coloring agent, to sell the product in retail stores.

Beyond Meat’s CEO isn’t sure grocery store shoppers will approve of his competitor. “We know the consumer doesn’t want soy in these burgers, so we’ve stayed away from that,” Brown said. “We know consumers don’t want GMOs, and we think (using them) is a bridge too far to convince Mom and Dad that plant-based meat is an amazing source of protein for the kids.”

He’s not alone in throwing shade. Kliman plays up the success Impossible Foods’ team has had in replicating the 200 flavor compounds, including heme, that make beef taste like beef when it’s seared in a hot pan. Beyond Burgers are pre-flavored to taste like cooked meat, she said. “We are generating flavor upon cooking, and that’s completely different from the Beyond formats,” Kliman said.

Until this year, Beyond Meat has dominated the grocery market and Impossible Foods has owned restaurant sales. With Beyond Meat’s December launch at 1,000 Carl’s Jr. locations — the company’s first major fast-food conquest — and Impossible Foods’ forthcoming retail rollout, the companies are now battling for customer loyalty.

So the question becomes: Which one tastes better? At back-to-back tastings at Carl’s Jr. and Gott’s (which already sells the Impossible Burger 2.0), the two new versions demonstrated they tasted dramatically different from versions 1.0 — and from each other.

The Carl’s Jr. Beyond Burger ($9.49) greeted the nose with a swaggering smokiness and beef-like aroma that hit hard and lingered long. Prepared by the fast-food chain, its porous texture resembled that of the McRib, McDonald’s cult pressed-pork sandwich. Gott’s Impossible Burger ($12.99) benefited from a brioche bun and higher-caliber fixings. The patty, which formerly tasted like wheat gluten spritzed with coconut oil and beef bouillon, better mimicked a real hamburger in its texture, its beefy flavor more amplified.

Beyond Meat won the last round of the burger battle. This round goes to Impossible Foods.

Both companies continue to work on version 3.0, as well as new products. “We’re humble. We know we’re not there yet,” Beyond Meat’s Brown said. “We have to provide people a seamless experience with what they love.” His company released a line of plant-based sausages in 2018 that, when grilled and topped with kraut and mustard, taste more like pork bratwursts than either 2.0 burger does beef.

According to David Lee, chief operations officer of Impossible Foods, his company continues to test 100 prototypes a day — and has set its sights on steak. The limit, he added, isn’t on how fast they can innovate. “We’re trying to be thoughtful about how we increase capacity, but we have enough demand to want to sprint,” he said.

Jonathan Kauffman is a San Francisco Chronicle staff writer. Email: jkauffman@sfchronicle.com Twitter: @jonkauffman