The future of protein could be a meal worm, a fungus, an obscure plant or a run-of-the-mill pea.

“If we look around the world, there’s a big consumer trend on more protein,” says Mehmood Khan, vice chairman and chief scientific officer at PepsiCo Inc. “The question is: How are we going to do this in a manner that’s sustainable? Protein isn’t cheap. And animal protein has the greatest footprint on the planet.”

The...