Brewing waste used for biofuel and food

Researchers have developed a way to extract the proteins in brewing waste products for use in food and biofuel

Spotted: As anyone who has ever brewed beer knows, the process produces huge mounds of leftover grain. This “spent” grain is what remains after the flavour has been extracted in the brewing process – but it still contains a lot of protein and fibre. Up to now, the main use of spent grain has been as animal feed, but researchers at the Virginia Polytechnic and State University (Virginia Tech) have recently found a way to turn the protein in spent grain into biofuels and more.

The researchers, who presented their results at the spring meeting of the American Chemical Society, developed a novel wet milling fractionation process to separate the protein in the grains from the fibre. Unlike other processes, this one did not involve drying the grains first – which saves a lot of energy. Instead, enzymes are used to aid in separating the fibre and proteins. The result is then sieved to produce two products: a protein concentrate and a fibre-rich product.

Initially, the research team, led by Haibo Huang, PhD, proposed using the protein concentrate as a more sustainable replacement for fishmeal to feed farmed shrimp. However, they also believe the protein could be used as an ingredient in human food products. For the fibre-rich product, they have found that a newly-discovered species of Bacillus lichenformis can be used to convert sugars to 2,3-butanediol, a compound that is used to make products such as synthetic rubber and the fuel 2-butanol. 

This would mean that both the protein and the fibre could be sustainably converted into a protein source, biofuels, plastics and more. Yanhong He, a graduate student who is presenting the work at the meeting explained: “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.” Huang added: “There is a critical need in the brewing industry to reduce waste.”

Spent grain joins a rapidly growing list of agricultural waste products that are being sustainably repurposed for new uses. Almost every week brings another development in this fast-growing space. At Springwise, we have recently covered the use of unwanted oranges for generating electricity and an organism that can turn cardboard into biofuel.

Explore more: Agriculture & Energy Innovations | Sustainability Innovations