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Corn Kernel Structural Integrity: Analysis Using Solvent and Heat Treatments¹

¹Journal Series No. 12519, Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln. ²Former research assistant, Cereal/Oilseed Science and Technology Laboratory, Dept. of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68583-0919. Currently research scientist, Cargill, Dayton, OH 45414. ³Professor, Cereal/Oilseed Science and Technology Laboratory, Dept. of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68583-0919. ⁴Corresponding author. E-mail: djackson@unlnotes.unl.edu

Most corn (Zea mays, L.) processing is accomplished by causing a structural change to the kernel. Associations between corn endosperm structural components were characterized using textural analysis after solvent and heat treating kernels. Intact Asgrow 405W and B73xMo17 kernels were incubated and treated at 20, 40, 55, and 90°C for 1, 24, and 48 hr in static air, in acetone, and in aqueous solutions of water, calcium chloride, sodium chloride, sodium bisulfite, lactic acid, lime, lye, ethanol urea, and sodium dodecyl sulfate (SDS). After treatment, kernels were compressed between flat platens. Acetone did not significantly soften endosperm structure. Ethanol reduced kernel fracturability by weakening cell-to-cell (wall) bonds, but ethanol did not effectively reduce kernel hardness. Water and aqueous solvents swelled and softened kernels by plasticizing structural components. Bisulfite and SDS softened kernels more than water only soaks because they denatured matrix proteins. Alkaline soaks reduced fracturability and softened the kernel by dissociating both cell-to-cell and intracellular (starch-protein) bonds. Soaking for longer periods and at higher temperatures increased aqueous-based solvent softening effect. Urea imbibition into the kernel and its softening effects were highly dependent on time and temperature of soak. Endosperm structural integrity is the governed by a combination of cell-to-cell bonds and intra-cellular (starch-protein) bonds. Reagents that denatured the endosperm matrix proteins and disrupted hydrogen bonds resulted in the greatest alterations to kernel structural integrity. Ultimately a better understanding of kernel structural integrity will lead to the development of improved hybrids and process technologies designed to facilitate desirable structural changes.