07-Apr-2021 - American Chemical Society (ACS)

Biofuels from the brewery?

Separating beer waste into proteins for foods, and fiber for biofuels

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. 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.

The researchers present their results at the spring meeting of the American Chemical Society (ACS). ACS Spring 2021 is being held online April 5-30. Live sessions will be hosted April 5-16, and on-demand and networking content will continue through April 30. The meeting features nearly 9,000 presentations on a wide range of science topics.

"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.

However, that still left the remaining fiber-rich product without a specific use. Last year, Huang's postdoctoral researcher Joshua O'Hair, Ph.D., reported finding a new species of Bacillus lichenformis in a spring at Yellowstone National Park. In the paper, they noted that the bacteria could convert various sugars to 2,3-butanediol, a compound that is used to make many products, such as synthetic rubber, plasticizers and 2-butanol, a fuel. So, He pretreated the extracted fiber with sulfuric acid, then broke it down into sugars from cellulose and hemicellulose. She then fed the sugars to the microbe, producing 2,3-butanediol.

Next, the team plans to work on scaling up the process of separating the protein and fiber components in order to keep up with the volume of spent grain generated at breweries. They are also working with colleagues to determine the economic feasibility of the separation process, as the enzymes currently used to separate the protein and fiber components are expensive. Huang and He hope to find suitable enzymes and green chemicals to make this process even more sustainable, scalable and affordable.

Facts, background information, dossiers
  • grains
  • wet milling
  • fractionation
More about American Chemical Society
  • News

    A candlelight-like glow from a flexible organic LED

    Giving off a comfortable glow, candles set the ambiance for a special dinner or just a quiet evening at home. However, some lighting alternatives, such as electronic candles, give off unwanted blue wavelengths that interfere with the body’s circadian rhythm. Now, researchers reporting in AC ... more

    Growing extremely tiny, uniformly sized diamonds — without explosives

    Diamonds aren’t just glittery, sparkly gems for jewelry. The smallest ones, only a few nanometers wide, are also crucial for drug delivery, sensors and quantum computer processors. Producing diamond nanoparticles that are consistently sized is important to the success of these technologies. ... more

    A previously unknown bacterial enzyme makes new type of biodegradable polymer

    Strings of sugars called polysaccharides are the most abundant biopolymers on Earth. Because of their versatile and environmentally friendly properties, these molecules could eventually replace some plastics. Now, researchers reporting in ACS Central Science have identified a previously unk ... more

  • Videos

    What Makes Rubber Rubbery?

    Reactions is looking at sports science today. Sports balls owe their reliability to an unusual polymer. Learn about the chemistry of rubber the all-star’s best friend! more

    Dragon's Blood Could Save Your Life

    This week Reactions is looking at chemistry in bizarre places that could save your life. The science within the blood of the Komodo dragon or in a horseshoe crab can help with antibiotic resistance. But it doesn't end there, so we're taking a closer look at other wild places in nature that ... more

    Why is Olive Oil Awesome?

    Whether you sop it up with bread or use it to boost your cooking, olive oil is awesome. But a lot of chemistry goes on in that bottle that can make or break a product. Take the “extra virgin” standard: Chemistry tells us that a higher free-fatty-acid content leads to a lower grade, less tas ... more