Scientists and industries are discovering innovative new uses for brewers' spent grain, the largest waste product of the beer brewing process.

When thinking about a well-crafted beer, most people envision a glass filled with golden liquid, refreshing and ready to drink. However, what’s often overlooked is the enormous pile of wet, sticky grain that accumulates as the primary waste from brewing beer.

This by-product is known as brewers' spent grain, and it’s produced in massive quantities. For every liter of beer brewed, about 200 grams (7 ounces) of spent grain are generated. Worldwide, this adds up to around 37 million tonnes annually—roughly the weight of 340 double-decker buses every hour. As beer consumption continues to rise (with sales expected to increase by a third over the next seven years), the amount of spent grain produced will only grow.

Currently, about 70% of brewers' spent grain is repurposed as animal feed, particularly for cattle, while 10% is used for biogas production. Unfortunately, about 20% ends up in landfills, where it decomposes and releases methane, contributing to environmental concerns and costing breweries in disposal fees.

However, inside this beer waste lies a wealth of valuable chemicals, including proteins. Researchers and companies are beginning to explore how these could be used more effectively.

One such company is the Swiss start-up Upgrain, which, in 2024, introduced a system to process brewers' spent grain into protein and fiber, both deemed safe for human consumption by the U.S. Food and Drug Administration and the European Food Safety Authority. After all, brewers' spent grain is still just grain. Upgrain’s system, designed for easy installation at breweries, comes in two sizes: a compact version for microbreweries and a larger unit for bigger operations like Brauerei Locher, Switzerland’s second-largest brewer. This larger unit, which opened in September 2024, is expected to host Europe's largest on-site processing facility for spent grain.

William Beiskjaer, Upgrain’s co-founder, describes brewers' spent grain as a "hidden treasure" for sustainable and nutritious food options. He believes it has great potential to address the growing global demand for protein. "There’s an increasing need for our foods to be enhanced, especially to boost protein and fiber content in our diets," he says.