When Dan Kurzock started brewing his own beer in 2010, his fraternity brothers at the University of California, Los Angeles, were psyched.

A frat with its own in-house brewery is about as good as it gets. Kurzrock’s popularity soared even more when he started to use the leftover grain from brewing to bake bread, the perfect hangover cure.

That’s what sparked the idea for ReGrained, a startup Kurzrock co-founded with fellow student Jordan Schwartz in 2013, which uses grain waste from small city breweries to make snack bars.

“Brewers are great environmental stewards,” said Kurzrock. “It’s not a decision to waste, but there’s no way to produce beer without generating a lot of spent grain.”

Grain is a key ingredient in beer. Typically barley, though sometimes rye or oats. To make beer, the grain gets cracked to expose the starches. It is then steeped in warm water, where the starches start to break down into simple sugars, which become alcohol. This process leaves brewers with huge amounts of leftover grain.