Home brewing enthusiasts and major manufacturers alike experience the same result of the beer-making process: mounds of leftover grain. Once all the flavor has been extracted from barley and other grains, what’s left is a protein- and fiber-rich powder that is typically used in cattle feed or put in landfills. Today, scientists report a new way to extract the protein and fiber from brewer’s spent grain and use it to create new types of protein sources, biofuels and more.

“There is a critical need in the brewing industry to reduce waste,” says Haibo Huang, Ph.D., the project’s principal investigator. His team partnered with local breweries to find a way to transform leftover grain into value-added products.

“Spent grain has a very high percentage of protein compared to other agricultural waste, so our goal was to find a novel way to extract and use it,” says Yanhong He, a graduate student who is presenting the work at the meeting. Both Huang and He are at Virginia Polytechnic and State University (Virginia Tech).

Craft brewing has become more popular than ever in the U.S. This increased demand has led to an increase in production, generating a major uptick in waste material from breweries, 85% of which is spent grain. This byproduct comprises up to 30% protein and up to 70% fiber, and while cows and other animals may be able to digest spent grain, it is difficult for humans to digest it because of its high fiber content.

In order to transform this waste into something more functional, Huang and He developed a novel wet milling fractionation process to separate the protein from the fiber. Compared to other techniques, the new process is more efficient because the researchers do not have to dry the grain first. They tested three commercially available enzymes — alcalase, neutrase and pepsin — in this process and found that alcalase treatment provided the best separation without losing large amounts of either component. After a sieving step, the result was a protein concentrate and a fiber-rich product.

Up to 83% of the protein in the spent grain was recaptured in the protein concentrate. Initially the researchers proposed using the extracted protein as a cheaper, more sustainable replacement for fishmeal to feed farmed shrimp. But more recently, Huang and He have started to explore using the protein as an ingredient in food products, catering to the consumer demand for alternate protein sources.

> Source: EurekAlert!