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Recovery of sorghum wax from selected processes

Karen Rosanne Lochte-Watson, University of Nebraska - Lincoln


Sorghum wax has a high melting point compared to natural waxes commercially available. Commercial extraction of grain sorghum wax as a co-product may provide additional income to sorghum producers and processors. ^ Sorghum wax extracted by hexane was estimated after harvesting, dry milling and wet-peeling. Wax yield and quality were assessed for wax extraction parameters and sorghum co-products containing concentrated amounts of bran. ^ Sorghum wax yield was not significantly reduced given the harvesting and handling methods tested, although a test to simulate excessive kernel breakage did result in a 25% loss of wax. A tangential abrasive dehulling device (TADD) used to simulate dry-milling resulted in less than 85% of the total wax recovered in abraded bran fractions. A pilot scale wet-peeling process, using a centrifugal pump, concentrated 90% wax into two separate fractions, wet-peeled bran and suspended solids, which accounted for less than 12.7% of initial dry matter. ^ Sorghum wax quality and yield were assessed for a number of extraction parameters including moisture content, solids to solvent ratio, and extraction time. Maximum wax yield occurred at moisture contents of 12% and 30% for whole kernels and bran, respectively. Multiple short reflux periods recovered more wax than a single 30 minute difference was found for solids to solvent ratios tested. Wax quality parameters tested were not affected by extraction parameters. Quality of sorghum wax was compared to carnauba and paraffin wax. ^ Yield and quality of wax recovered from concentrated bran co-products of two dry-milling operations, two ethanol processes, and a lab “wet-peeling” process were evaluated. A significant difference in yield and quality was found between wax recovered from sorghum samples. ^ A conservative cost to extract sorghum wax was estimated to be $3.00 or $4.35/kg depending upon source. The process was scaled using three extraction vessels which could produce 425,000 kg of wax per year or less than 15% of total carnauba wax imports with an average customs' value of 3.96/kg. ^

Subject Area

Agriculture, Food Science and Technology|Engineering, Agricultural

Recommended Citation

Lochte-Watson, Karen Rosanne, "Recovery of sorghum wax from selected processes" (2001). ETD collection for University of Nebraska - Lincoln. AAI3004616.