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United States Department of Agriculture

Agricultural Research Service

Title: Methods for Decolorizing Corn Zein

Authors
item Sessa, David
item Eller, Fred
item Lawton Jr, John

Submitted to: Cereal Chemistry
Publication Type: Abstract Only
Publication Acceptance Date: January 10, 2002
Publication Date: October 13, 2002
Citation: SESSA, D.J., ELLER, F.J., LAWTON JR, J.W. METHODS FOR DECOLORIZING CORN ZEIN. CEREAL CHEMISTRY. 2002. Abstract p. 100.

Technical Abstract: The yellow color of corn and corn processing coproducts is due to xanthophylls and carotenes. Colorless zein commands a premium price and the resulting extracted carotenoids possess nutraceutical value. Our objective was to devise methods for decolorizing zein. Methods include: supercritical carbon dioxide extraction of zein with alcohol entrainers; ultrafiltration/diafiltration of ethanolic solutions of zein on a tangential flow system; partitioning of zein ethanolic solutions with toluene; batch treatment of ethanolic zein solutions with activated carbon. Color removal was assessed by dissolving either a zein control or decolorized zein in glacial acetic acid, filtration of each solution through glass fiber filters, preparation of a series of dilutions and reading absorbances of each dilution at 448nm. Comparative logarithmic regressions of each series of control zein and decolorized zein dilutions were used to determine degree of color removal. Results showed that partitioning zein solutions with toluene gave the least color removal. Supercritical carbon dioxide extraction with 15 percent ethanol entrainer for 15 minutes at 10,000 psi and 70 degrees C decolorized zein to a similar extent as diafiltration of zein ethanolic solutions ultrafiltered through 5000 MWCO membranes. Both methods gave excellent yields of decolorized product. However, the supercritical carbon dioxide method had the advantage of no need to spray dry the final product and did not require the copious aqueous ethanol volumes needed for color removal. The most complete removal of color was achieved by batch treatment with activated carbon. Recovered yield, however, was lowest of all the other methods evaluated.

Last Modified: 9/10/2014
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