From Beer Waste to Micoprotein: Fungal Cultivation for Sustainable Protein Development

Key insights from an interview with Luís Abrunhosa (UMINHO), based on an article in Perspetiva Atual

Researchers in Protein4Impact are developing new approaches to sustainable protein production that respond to nutritional, environmental and societal needs. One of the research pathways focuses on cultivating edible fungi using brewer’s spent grain as a nutrient source.

At the University of Minho (UMINHO), Luís Abrunhosa and his colleagues, Eduardo Coelho and Vítor Sousa, are investigating how Pleurotus ostreatus, a well‑known oyster mushroom, can grow on brewer’s spent grain (BSG) under submerged conditions, transforming this underused by‑product of beer production into micoprotein through fungal cultivation.

Why were the fungi and brewer’s spent grain chosen?

Brewer’s spent grain (BSG) is the most abundant by‑product of the brewing industry. Rich in fibre and residual nutrients, it is typically underused despite its potential. For Abrunhosa, this makes it an ideal substrate for P. ostreatus fermentation: “We want to create protein sources that are safe, nutritious and attractive for consumers,” he explains. Using spent grain as a nutrient source allows us to explore circular, sustainable solutions that make sense both scientifically and societally. Cultivating Pleurotus ostreatus on BSG produces fungal biomass, a micoprotein source that will now be evaluated across the Protein4Impact consortium for its nutritional, sensory and functional properties.

Fig 2. Example of P. ostreatus growth in small scale flasks for inoculum production.

Micoprotein: a microbial alternative with growing relevance

Micoprotein is gaining attention as a promising category of alternative proteins. Derived from fungal biomass, it typically offers high‑quality protein, favourable amino‑acid profiles, dietary fibre (including beta‑glucans), a low environmental footprint and strong alignment with circular bioeconomy principles.

What happens after the micoprotein is produced?

Once the micoprotein is produced at the University of Minho (UMINHO), it is transferred to other Protein4Impact partners, who analyse a different aspect of its performance, nutritional properties, safety and potential contaminants or allergens, sensory characteristics and palatability, functional behaviour in food applications, environmental impacts using LCA methodologies, techno‑economic feasibility and scalability, process optimisation through Digital Twins and modelling tools.

Scaling up the process

As Abrunhosa notes in the interview, the team at UMINHO has already successfully established the cultivation of Pleurotus ostreatus on brewer’s spent grain and scaled the fermentation process to a 3‑litre bioreactor. The next phase will focus on transferring the process to a larger airlift bioreactor, a step designed to support more efficient operation and assess the economic viability of the approach.

This progression reflects the Protein4Impact’s broader aim: generating robust, scalable knowledge that can inform future sustainable protein production pathways.

The original interview in Portuguese is available here: Novas respostas para velhos desafios nutricionais – Perspetiva Atual

Fig 3. First trial of Pleurotus ostreatus grow in a airlift bioreactor in BSG culture medium.