Taco Bell and Panera are refusing to jump on the faux meat bandwagon, as the chains double down on plant-based proteins in less processed forms.

Executives from Panera Bread and Taco Bell told Business Insider that their customers are more interested in "whole food" fruits and vegetables than meat alternatives.

Chains including Del Taco, Burger King, and Tim Hortons have announced deals with Beyond Burger or Impossible Foods in recent weeks to add plant-based "meat" options to the menu.

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As fast-food chains jump on the vegetarian bandwagon, some long-time pushers of plant-based protein are abstaining from partnerships with meat alternatives makers like Beyond Meat and Impossible Foods.

Executives from Panera Bread and Taco Bell separately told Business Insider this week that, after consideration, they felt their menus did not currently need a faux meat option courtesy of Impossible Food or Beyond Meat. Instead, they said, they have spent years expanding the plant-centric options on their menus — making jumping on the bandwagon unnecessary.

"We continue to see our customers really looking for ... that whole food solution, and we're continuing to lean into that," said Sara Burnett, Panera's vice president of wellness and food policy. "Because hands down, we have the best pantry, I think, of anyone in the industry."

Panera has been building out its vegetarian and plant-based options for years, in an effort to beef up the nutritional bonafide of its menu — including options that contain meat.

"We're going to see more vegetables," Panera's head chef Dan Kish told Business Insider back in 2016.

"We're going to see culinary treatments of those vegetables in ways that bring out their flavors without adding a lot of other things to it — so keeping things as natural as possible. Upping the percentage of vegetables in your diet — [it] is part of our job to help you with that."

Taco Bell bucks the fast-food trend

Taco Bell has similarly been building out its vegetarian menu options for years.

"We're vegetarian-certified and have been since 2015," Julie Felss Masino, Taco Bell's president of North America, told Business Insider on Wednesday. "Nobody else is certified by the American Vegetarian Association."

Masino told Business Insider that the chain plans to launch an American Vegetarian Association-certified menu nationwide, rolling out the panel to stores across the US this fall. However, Taco Bell is also avoiding partnerships with Beyond Meat or Impossible Foods in favor of whole foods.

"We love what we're doing with real plant-based proteins, with refried beans and black beans and ... potato bites," Masino said.

Read more: Taco Bell plans to roll out vegetarian menu boards across America— but don't expect Impossible Tacos or Beyond Burritos to be featured

Many fast-food rivals are focused on burgers and sandwiches, Masino said. When burgers are the backbone of the menu, she said, it makes more sense to rely on faux "meat" makers that can produce vegan imitations of fast-food classics.

Beyond Meat and Impossible Foods' fast-food takeover

White Castle's Impossible Slider. Sarah Jacobs/Business Insider

Masino's theory has been proven in the swell of fast-food partnerships with alternative meat makers in recent weeks.

Burger King is rolling out Impossible Whoppers across the US by the end of the year. Tim Hortons is rolling out Beyond Meat breakfast options in Canada. And, Del Taco announced on Wednesday that its Beyond Tacos were one of its most popular menu launches of all time.

Even chains that haven't rolled out a plant-based menu item yet are considering it. Executives from KFC and Chick-fil-A told Business Insider that the chains have spoken with or are currently meeting with plant-based "meat" makers.

Amanda Norris, the executive director of Chick-fil-A's menu, said she believes that every chain is going to have a "point of view" on plant-based menu items. Whether a brand rolls out its own version of an Impossible Whopper or decides against doing so will be a decision that says something specific about the chain.

"We're certainly wanting to broaden our thinking and really start big in that funnel and come down," Norris said. "We think it is certainly beyond just no meat on salads or no meat in a wrap. It might be some kind of alternative protein on a sandwich."

Top plant-based "meat" makers have been thriving as new deals are announced on an almost daily basis.

On Wednesday, shares of Beyond Meat traded up more than 550% since the initial public offering in May, despite a stumble on Wednesday following Taco Bell's snub. And, while Bloomberg reports that Impossible Foods has struggled to keep burgers in stock at Red Robin and White Castle, the company raised $300 million in funding in May to improve its ability to keep up with demand.