Protein Concentrate Production from Thin Stillage

Two-stage fermentation (TSF) of saccharified wheat with a consortium of endemic lactobacilli produced CO₂ and induced colloid separation of fermented solution to produce a protein concentrate (PC). Protein-rich slurry (50%, db) was obtained by decanting solution or skimming floating material during or after TSF. Washing and drying processes were explored to improve protein content, extend storage life of slurry, and yield converted stillage for compound recovery. Centrifuging and washing slurry afforded a PC and clarified solution. PC protein content increased to 60% (w/w, db). The PC was dried in a spray dryer or drum dryer or tray dryer. Dried PC water activity ranged 0.23–0.30. The dried PC lysine content was low, but lysine availability (95%) was excellent. Liquid from TSF and washing was readily microfiltered. Mass recovery of protein, glycerol, 1,3-propanediol, lactic acid, acetic acid, and glycerylphosphorylcholine from combined TSF, washing, and filtration were 66, 76, 72, 77, 74, and 84%, respectively.