The process combines spent grain with oyster mushrooms to produce a protein-rich base for products such as vegan nuggets and sausages.

I went looking to see if there were more details, and the German Gretranke News (Beverage News) had this article that explains it in more detail.

In the pilot plant, brewer's grains are processed into a protein-containing mycelium mass with the help of fungal fermentation. The aim of the project is to develop a technical solution that allows breweries to produce proteins directly on their own site – without additional personnel costs. The plant is currently used to optimize the fermentation process as well as the quality of the end product, an oyster mushroom-based mycelium.

According to the company, the process works regardless of the type of spent grain used - for example from barley, wheat or rye. The aim is to standardize the processes by 2026 under different operating conditions and thus prepare for market maturity. The mycelium mass produced is currently used for tests in food processing, for example for the development of meat alternatives.

In the long term, Eat Beer wants to offer a platform solution that can be adapted to different brewery structures. "Each company works with its own raw materials, recipes and processes. Our system must be flexible enough to reflect these differences," says Managing Director Malte Nordmann. In the future, the software will control the entire fermentation and production process on a site-by-site basis.

Raw pellets:

Processed into "bratwurst":

Sounds somewhere between regular mushroom growing, except the mycelium matrix is the end goal rather than formed mushrooms and the process to make tempeh. Looks and sounds very exciting!