Restaurants are lining up to put meat substitutes from Beyond Meat Inc. and Impossible Foods Inc. on their menus — but don’t expect Chipotle Mexican Grill Inc. to join them.

Chief Executive Officer Brian Niccol said the companies’ products are too processed for the burrito chain, which touts its simple food and a menu that uses only 51 ingredients.

“We have spoken to those folks and unfortunately it wouldn’t fit in our ‘food with integrity’ principles because of the processing, as I understand it, that it takes to make a plant taste like a burger,” Niccol said in an interview. “If there’s a way for them to do this that would match our ‘food with integrity’ principles, I’m sure we would continue talking with them.”

Chipotle is currently doing all of its culinary development of new products internally, he added.

In response, Beyond Meat CEO Ethan Brown invited Chipotle to visit its factory in Columbia, Missouri, and suggested that meat producers are worse.