46C-6 |
Composition of waxes extracted from grain sorghum kernels and distillers dry grains |
K. T. HWANG, Department of Food Science and Human Nutrition, Chonbuk National University, Chonju, Chonbuk, 561-756, South Korea, C. L. Weller, Department of Biological Systems Engineering, University of Nebraska, Lincoln, NE 6583-0726, S. L. Cuppett, Department of Food Science and Technology, University of Nebraska, Lincoln, NE 68583-0919, and M. A. Hanna, Industrial Agricultural Products Center, University of Nebraska, Lincoln, NE 68583-0730. Grain sorghum wax has been noted to have physical properties similar to carnauba wax. However, the few studies on the chemical composition of the wax that have been published are not in agreement. The limited and conflicting chemical information on sorghum wax has hindered application attempts for the wax. Recently, in our lab, the major components in sorghum wax were identified as fatty aldehydes, fatty alcohols, and fatty acids, and HPLC methods were developed for analyzing sorghum wax composition. The objective was to determine and compare compositions of waxes extracted from grain sorghum kernels and distillers dry grains (DDG). Wax was extracted using hot hexane or ethanol from kernels of 4 different grain sorghum hybrids grown in 1996, 1999, and 2000. Wax was extracted also from grain sorghum DDG using hot hexane. Wax composition was determined using our HPLC method. Waxes extracted from grain sorghum kernels contained 36-55% (w/w) fatty aldehydes, 37-55% fatty alcohols, 3.9-5.5% fatty acids, 0.5-1.1% hydrocarbons, and 0.3-0.4% triacylglycerols (TG). Wax extracted from the kernels using ethanol was higher in aldehydes and hydrocarbons than hexane-extracted wax. Waxes extracted from white sorghum using hexane contained more aldehydes than wax from red sorghum. DDG wax contained 25.5% aldehydes, 35.1% alcohols, 5.7% acids, 18.0% wax esters, 12.7% TG, and 1.0% hydrocarbons. A considerably high level of aldehydes in sorghum wax implies their oxidative conversion to acids during storage or use. Further study of the chemical composition and functional properties of grain sorghum wax will instigate application attempts for the wax.
Session 46C, Food Chemistry: Lipids, antioxidants and emulsifiers
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