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Beer Waste Can Now Be Turned Into Biofuel

It turns out that brewing beer results in leftover waste that can be put to good use.

The beer-making process results in lots of leftover grain that is a protein and fiber-rich powder typically used in cattle feed or landfills. Now, Virginia Polytechnic and State University (Virginia Tech) scientists have found a way to make this leftover grain useful by extracting the protein and fiber held inside it and using it to create new types of protein sources, biofuels, and more.

“There is a critical need in the brewing industry to reduce waste,” Haibo Huang, Ph.D., the project’s principal investigator said. Huang and his team collaborated with local breweries to find a way to transform leftover grain into valuable 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,” Yanhong He, a graduate student who is presenting the novel work at the spring meeting of the American Chemical Society, said. 

Spent grain comprises up to 30% protein and up to 70% fiber, making it difficult for humans to digest. Huang and He, therefore, decided to transform the waste into something more functional and developed a novel wet milling fractionation process to separate the protein from the fiber.

They used an alcalase treatment to turn the spent grain into a protein concentrate and a fiber-rich product. Up to 83% of the protein in the spent grain was recaptured in the novel concentrate. 

The researchers then further explored using the protein as an ingredient in food products but that still wasn't enough. The next step was using bacteria to turn it into fuel.

The researchers used a new species of Bacillus lichenformis found in a spring at Yellowstone National Park to convert spent grain to 2,3-butanediol, a compound that is used to make many products, such as synthetic rubber, plasticizers, and 2-butanol, a fuel. The team is now working on finding cheaper more accessible enzymes to separate the protein and fiber components in order to make this process more affordable and sustainable.

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