Brewing – Brew house residues should be used sustainably

The teams of Professor Dr. Roland Ulber (left), Professorin Dr. Elke Richling, and Professor Dr. Werner Thiel are investigating how the spent grain can be used in other ways. (Photo: TUK/Thomas Koziel)

Daniela Becker and Jens Weiermüller are also involved in the project. (Photo: TUK/Thomas Koziel)

In 2016, each German drank an average of 104 liters of beer. Brewing this malted barley beverage produces many residues, totaling approximately 400,000 tons annually across Europe. Only a portion of this is recycled as animal feed. Researchers from three disciplines at the Technical University of Kaiserslautern (TUK) are working on sustainable ways to utilize this waste, for example as a raw material for the chemical industry or as a source of pharmacologically active compounds, in a European project. They will present their project from June 11 to 15 at the Process Industry Fair Achema in Frankfurt at the Rheinland-Pfalz research stand (Hall 9.2, Stand A86a).

During brewing, yeasts convert the sugars contained in malt into alcohol and carbon dioxide during fermentation. Microorganisms also need other components from the cereal malt to grow and reproduce. Nevertheless, a lot of waste is generated in this process. These residues, also known as spent grains in technical circles, still contain many valuable substances. This is where the project comes in, with three working groups from TUK collaborating with partners: they are investigating how the spent grains can be used sustainably and resource-efficiently in the future.

At Professor Dr. Roland Ulber's Department of Bioprocess Engineering, the team around doctoral students Jens Weirmüller and Alexander Akermann is exploring what substances are produced when the brewing residues are further fermented. "We use various microorganisms such as fungi and bacteria," says Akermann. These processes produce a variety of chemical products, such as lactic acid. In the future, this could serve as a starting material for bioplastics for industry.

The team led by Professor Dr. Werner Thiel and doctoral students Ranja Saynisch and Pascal Weingart in Inorganic Chemistry is examining the fats present in the spent grains. "They contain, for example, numerous unsaturated fatty acids that yeasts do not need during fermentation," says Thiel. The chemists first want to identify these substances more precisely. In the next step, they aim to process them into products for industry. "Glycerin can be obtained from the fats, which can be converted into intermediate products for the chemical industry," the professor continues. "Among other things, unsaturated fatty acids can be used as precursors for plastics. We will develop the necessary catalysts for this."

The team from the Department of Food Chemistry and Toxicology, led by Professor Dr. Elke Richling, along with doctoral students Daniela Becker and Verena Kirsch, will investigate substances and extracts obtained from the residues, including those from project partners. They will first examine their biological activity, particularly potential toxicological effects. "We need to ensure that these substances pose no health risks," says Kirsch. Additionally, they will study how these substances influence human sugar metabolism. "There is some evidence that various compounds from the spent grains can inhibit sugar absorption into the blood," Becker adds. "We will look into their exact effects." Possibly, the insights gained could one day influence glucose metabolism, which is highly relevant for diabetes treatment.

The "BIOVAL" project involves TUK, Saarland University, and universities in Lorraine, Luxembourg, and Liège, as well as the Belgian company Celabor. It is funded by the European Regional Development Fund (ERDF) with 1.84 million euros. The total budget exceeds three million euros.

At Achema, the teams from the three working groups will present the project.