Brazilian researchers at UFRJ have shown that brewer's spent grain, the main solid waste from beer production, can feed the yeast Yarrowia lipolytica to make protease enzymes. After optimizing the growth medium, they got a fivefold increase in enzyme yield, with the best results at moderate nitrogen limitation rather than high nitrogen input. The enzyme works at mild temperatures and neutral pH, which fits post-fermentation jobs like haze reduction and protein adjustment in breweries. It also held up for 120 days under refrigeration. The study is a preprint and used a crude enzyme extract, so the next step is pilot scale validation before commercial use. This kind of waste valorization reduces disposal pressure and keeps value inside the brewing chain.
