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Cheers! Method for turning spent grain from beer production into biofuels and plant-based foods developed

Published: 06th April, 2021 at 16:07
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The technique could be used to produce animal feed, protein for use in human foods, synthetic rubber, materials for creating plastics, and biofuels, the researchers say.

Whether your go-to tipple is a crisp Bohemian-style pilsner, a dark and roasty stout, or a dank American-style IPA, all styles of beer have one thing in common: producing them creates mounds and mounds of leftover barley and other grains.


Traditionally, this by-product has been used in cattle feed or simply put into landfill. But now, researchers at Virginia Polytechnic and State University (Virginia Tech) have developed an innovative method of extracting nutrients and fibre from spent grain for use in new food sources and biofuels.

Spent grain accounts for around 85 per cent of the waste material produced from brewing. It is made up of 30 per cent protein and 70 per cent fibre. While suitable for consumption by cows, the high fibre content makes it difficult for humans to digest.

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“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,” said Virginia Tech graduate student Yanhong He.

In order to figure out a method of turning leftover grain into something more useful, the team partnered with local breweries. Together they developed a method of separating the grain into a protein concentrate and a fibre-rich material by treating it with alcalase, a commonly available enzyme, and then sieving it.

Through this method they were able to extract more than 80 per cent of the protein from the grain. Initially, they proposed that this could be used as a cheap, sustainable food for use in shrimp farms. But now, given the rise in the number of people switching to a plant-based diet, they are looking into using it as an alternative protein source in various foods for human consumption.


In a separate project, another team from Virginia Tech has developed a method of treating the fibre with Bacillus lichenformis, a species of bacteria recently discovered in a spring in Yellowstone National Park. By treating the fibre with the bacteria it is possible to convert various sugars within it to 2,3-butanediol, a compound that is used to make many products, such as synthetic rubber, materials for creating plastics, and biofuels.

Reader Q&A: Could we survive on beer alone?

Asked by: Cassandra Sturgeon Delia

It is not possible to survive indefinitely on beer alone. The drink contains water and sugar, along with some vitamins and minerals, but is deficient in other nutrients needed for the body to function properly, including protein, fat and thiamine (vitamin B1). It contains little or no vitamin C. With an average pint of beer containing around 240 calories, you would need at least eight pints per day to fuel the body. Over time, the high volume of alcohol would harm your liver and kidneys. Alcohol is a diuretic, so dehydration could also be an issue.

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.


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