Abstract
Spent yeast recovery is important in medium-scale breweries because yeast biomass can be reused, processed into value-added materials, or managed as part of sustainable brewery operations. This study examines spent yeast recovery and reuse strategies in medium-scale brewing. Yeast biomass was collected from fermentation vessels after primary fermentation and evaluated under different washing, storage, and reuse conditions. Cell viability, microbial contamination, glycogen reserves, membrane integrity, slurry density, fermentation performance, protein content, and by-product recovery potential were assessed. The results show that carefully washed and cold-stored yeast retained higher viability and supported more consistent repitching performance. Delayed recovery increased autolysis risk, off-flavour formation, and microbial instability. Spent yeast not suitable for repitching showed potential for protein-rich by-product recovery after proper stabilization. The study demonstrates that spent yeast management should combine quality screening, reuse limits, storage control, and sustainability planning. This improves brewing efficiency and reduces waste in medium-scale brewery operations.