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Antioxidant-Rich Foods Retard Lipid Oxidation in Extruded Corn

¹University of Maine, Dept. of Food Science & Human Nutrition, 5735 Hitchner Hall, Orono, ME. ²Corresponding author. Phone: 207.581.1627. Fax: 207.581.1636. E-mail: Mary.Camire@umit.maine.edu ³Natick Soldier Center, Natick, MA.

Antioxidant-rich plant materials could provide protection against oxidation in extruded foods and feeds, but their efficacy is not well established. Degermed yellow cornmeal was mixed with 0.02% (w/w) ascorbic acid or quercetin, or with 2% (w/w) spray-dried ginkgo extract, onion powder, potato peels, or wheat bran. The mixtures were processed in a laboratory-scale twin-screw extruder at a feed rate of 227 g/min. Water pump rate was 16 g/min; screw speed was 200 rpm. Mass temperature during extrusion averaged ≈170°C. Samples were cut into small spheres, dried to 5% moisture, then stored in trilaminate bags at 25°C. Ground sample headspace was assayed for hexanal and other volatile indicators of oxidation by gas chromatography. Ginkgo and potato peels significantly darkened the extrudates. Total soluble phenolics, as ferulic acid equivalents, were highest in the ginkgo sample. Volatile compounds were lower in several treatments during storage compared with the control. These findings suggest that manufacturers may be able to formulate products with improved shelf-life through addition of antioxidant-rich food materials.