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Solvent Extraction of Zein from Dry-Milled Corn

¹Agricultural Bioprocess Laboratory, University of Illinois at Urbana-Champaign, 1302 West Pennsylvania Avenue, Urbana 61801. ²Corresponding author. Phone: 217-333-9332. Fax: 217-333-9592. E-mail: mcheryan@uiuc.edu ³Department of Mechanical and Industrial Engineering, University of Illinois, Urbana.

Batch extraction of zein from dry-milled whole corn with ethanol was optimum with 70% ethanol in water, an extraction time of 30–40 min, and temperature of 50°C. High yields (60% of the zein in corn) and high zein contents in the extracted solids (50%) were obtained at a solvent-to-solids ratio of 8 mL of 70% ethanol/g of corn. However, zein concentration in the extract was higher at lower ratios. Multiple extraction of the same corn with fresh ethanol resulted in a yield of 85% after four extractions, whereas multiple extractions of fresh corn with the same ethanol resulted in high (15 g/L) zein concentration in the extract. Optimum conditions for batch extraction of zein were 45°C, with 68% ethanol at a solvent-to-solids ratio of 7.8 mL/g for an extraction time of 55 min. Column extractions were also best at 50°C and 70% ethanol; a solvent ratio of 1 mL/g resulted in high zein concentrations in the extract (17 g/L) but yields were low (20%).