Techno-economic analysis of protein concentrates production from brewer's spent grains

Brewers' spent grains (BSG) are the predominant byproduct of beer production, containing 20-30 % (w/w) protein and presenting a massive, untapped resource for the burgeoning plant-based protein market. Although bench-scale protein extraction from BSG has been extensively investigated, industrial-scale production remains bottlenecked by uncertain scalability and economic viability. Herein, this study evaluated the techno-economic feasibility of industrial-scale BSG protein production across three extraction methods: alkaline (Scenario 1), enzymatic (Scenario 2), and acidic (Scenario 3). Process simulation demonstrated that all three scenarios yielded protein concentrates with approximately 60 % purity, comparable to commercial plant protein concentrates; however, the yields differed at 15 % (alkaline), 26 % (enzymatic), and 10 % (acidic). To process 140,760 tonnes of BSG annually, total capital investment was estimated at $22.3, $21.0, and $30.8 million for Scenarios 1-3, respectively. Despite enzymatic extraction achieving the highest yield, alkaline extraction yielded the lowest Minimum Protein Selling Price (MPSP) at $2.4/kg, compared with $4.2/kg for enzymatic and $8.8/kg for acidic extraction. Sensitivity analysis indicated that MPSP is highly sensitive to protein production yield, processing capacity, and raw material costs. Overall, alkaline extraction yields an MPSP competitive with commercial plant proteins, offering a practical solution for brewery waste valorization and sustainable food ingredient development.