Composition and economic comparison of germ fractions from modified corn processing technologies

Several new processes for milling corn have been developed recently specifically to isolate germ as a value-added co-product and improve the profitability of dry-grind ethanol production. The present work used modified and conventional corn milling technologies to recover germ fractions from corn kernels using either wet or dry separation processes. This study determined the quality, composition, and yield differences among the corn germ produced and compared these properties with those of the conventional wet- and dry-milled germ. A method for calculating the estimated market value for germ produced by the alternative processing methods is given. There were significant differences in the oil, protein, starch, and ash compositions and in the estimated market values among germ fractions produced by the alternative milling processes. The different germ fractions produced (including the traditional wet-and dry-milled) were found to contain 18-41% oil, 13-21% protein, and 6-21% starch, depending on the milling process used. The estimated value of germ from these processes varied from as low as $0.058/lb ($0.128/kg) to a maximum of $0.114/lb ($0.251/kg), showing that the specific process used to produce the germ will have the major impact on the overall economics of the ethanol process.