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Quality of Corn Oil Obtained by Sequential Extraction Processing

¹Systems Bio-Industries, Waukesha, WI 53187. ²USDA, National Center for Agricultural Utilization Research, 1815 N. University St. Peoria, IL 61604-3999. ³Corresponding author. E-mail: dmyers@iastate.edu. ⁴Center for Crops Utilization Research and the Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50010-1061 ⁵Pillsbury Technology Center, Minneapolis MN 55414-2198. ⁶Delimex, San Diego, CA 92173.

Sequential extraction processing (SEP) is a new approach to fractionating dried, flaked corn using 95% ethanol. In the original process, corn oil was extracted at 76°C in a countercurrent mode while simultaneously dehydrating the ethanol. This resulted in 20% of the protein (predominantly zein) coextracting with the oil. The process was modified to reduce the amount of coextracted protein. One modification (mSEP1) was to use a blend of 30% hexane and 70% ethanol at 56°C. A second modification (mSEP2) used a longer extraction column (L/D ratio 15) to replace the column with L/D 2 used in the original SEP system. To determine the effect of the modifications on oil quality, the quality of the crude corn oils produced from the modified SEP processes were compared with the quality of oil from the original SEP. To evaluate the quality of the three crude oils produced by SEP with the process typically used in industry, they were compared with the quality of laboratory hexane-extracted corn oil. The results of the three SEP oils exhibited larger concentrations of fatty acids, phospholipids, and carotenoids, smaller concentrations of triacylglycerols, and darker red color than the hexane-extracted oil. The oils from the two modified SEP processes contained smaller concentrations of free fatty acids and phospholipids and larger concentrations of triacylglycerols and carotenoids than the original SEP oil. In spite of the improvements to the oil through process modifications, the mSEP1 and mSEP2 oils exhibit greater refining losses than hexane-extracted oil.