Production of Zein From Dry Milled Corn by Solvent Extraction and Ultrafiltration

153 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2000.This research focused on developing a process for the production of low cost zein from corn using a combination of solvent extraction and membrane technology. Extraction of zein from dry milled whole corn was optimum with 70% ethanol at 50°C using a solvent-to-solids ratio of 6 ml ethanol per g corn for 45 minutes. Zein concentration in extract was 3--9 g/l. Continuous column extraction was also best at 50°C and 70% ethanol; a solvent ratio of 1 ml/g resulted in zein concentrations of 17 g/l in the extract. Multiple extractions of the same corn with fresh ethanol resulted in a yield of 85% after 4 extractions, while multiple extractions of fresh corn with the same ethanol resulted in high zein concentration in the extract (15 g/l). The zein extracted in our research was comparable in amino acid analysis and SDS-PAGE profiles to commercial samples.Several commercially available polymeric and inorganic membranes were evaluated for stability, flux and rejection in aqueous ethanol solutions. Regenerated cellulose, surface-modified/cross-linked composite and ceramic membranes had better stability than polysulfone or cellulose acetate membranes.Three polymeric membranes and one inorganic membrane were selected for further studies with model zein solutions in a cross-flow cell. Flux with the Osmonics-Membrex MX25 was 45 liters per square meter per hour (LMH) at 5 g/l zein and 25 LMH at 150 g/l zein at 20 psi and 50°C. Zein rejections were 88% and the Cg value was 340 g/l. The Membralox 200 A ceramic membrane gave a flux of 70 LMH at 5 g/l zein at 15 psi and 50°C, with a zein rejection of 80%. Pilot scale trials done with real extracts confirmed model solution data.The process developed here can be easily integrated into any corn processing facility, especially dry-grind ethanol plants. The solvent extraction step involves only mixing and a filtration/centrifugation step. The filtered extract, after further treatment if necessary to improve protein purity, can be concentrated using solvent stable membranes to at least 250 g/l, which results in a recycle of over 97% of the extraction solvent, thus substantially lowering energy requirements.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD