161 Heat and solvent dissociation of maize endosperm structure.

D. L. SHANDERA and D. S. Jackson. Department of Food Science and Technology, 250 Food Industry Complex, University of Nebraska– Lincoln, Lincoln, NE 68583-0919.

Solvent and heat treatments were used to explore the role of various endosperm components in maize endosperm integrity. Vitreous endosperm meal was incubated at 20, 40, 55, and 90 C for 1, 24, and 48 hr in solutions of water, CaCl(2), NaCl, ethanol, lime, lye, urea, sodium dodecyl sulfate (SDS), sodium bisulfite, and acetone. Cavitational shear energies were applied to soaked meal by probe sonication. The ability of solvent and heat to dissociate maize endosperm structure was quantitatively characterized, and released material microscopically examined. Except for acetone soaks, the impact of solvents in dissociating endosperm components was enhanced with longer soak times and at higher soak temperatures. Lye completely dissociated cells, starch, and protein without substantial starch granule swell or loss of birefringence. In contrast, lime released less material and caused greater loss of birefringence. SDS and urea released only 50 percent of components, but released components were gelatinized. Ethanol did not release starch, but ethanol extracted zein bodies and weakened bonds between cells. Water and chloride salts partially weakened starch to protein bonds; protein remained identifiable as zein bodies and matrix honeycombs. Thiol reducing solvents caused the greatest dissociation of endosperm components.