Supercritical Fluid Extraction of Dry-Milled Corn Germ with Carbon Dioxide

Abstract

Dry-milled corn germ was extracted with supercritical carbon dioxide (SC-CO2) at 5,000-8,000 psi and 50°C. CO2-extracted oil was lower in free fatty acids and refining loss, and was lighter in color when compared with a commercial expeller-milled crude oil. Total unsaponifiable and tocopherol contents were similar for both oil types. The defatted, highly friable flour has a shelf-stable moisture content of 2-3% and good flavor quality. The flour contains 20% protein with good amino acid balance, meeting FAO specifications for food protein supplements. High pressure SC-CO2 extraction also denatures the proteins, including oxidative enzymes. Peroxidase activity is reduced tenfold in SC-CO2-extracted flour when compared with hexane-extracted flours. Storage tests for 5 wk at 38°C and for 2 months at 25°C show that flavor quality of untoasted SC-CO2-defatted germ flour is maintained even under these extreme conditions.