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In an enzymatic wet milling process, termed E-Milling, proteases are incubated with ground, hydrated corn to separate starch and protein in corn endosperm for wet milling. Use of enzymes would eliminate the need for SO2 and significantly reduce steep time, thereby increasing productivity. However, E-Milling introduces two process streams differing from their conventional wet milling counterparts. These streams are corn soakwater (CSW) and enzymatic gluten (EG). Gluten resulting from E-Milling differs from conventional gluten (CG) in that it contains proteases that may continue to break up proteins in EG after incubation. Membrane filtration could provide a method of recovering protein from CSW and EG during E-Milling.

Laboratory scale microfiltration (MF) with a 0.1 micron membrane and stirred cell ultrafiltration (UF) with membranes varying in pore size from 10,000 to 100,000 molecular weight cutoff were evaluated for dewatering of CSW, SW, CG and EG from 1 kg scale processes. Permeate flux rates during filtration and nutrient content of permeate and retentate streams, including solids, nitrogen and ash, were reported. MF was effective at dewatering CG at permeate flux rates that appear economically feasible. Large amounts of small MW proteins permeated during MF of EG. Some additional protein was recovered during subsequent UF of MF permeate. Permeate flux rates were comparable with those of CG. Permeate streams from MF of both CG and EG contained high levels of ash. MF and UF were not effective at recovering protein from SW and CSW.