Channels of maize and sorghum starch granules

The radial, tube-like channels of corn/maize and sorghum starch granules, w hich penetrate from the external surface inward toward a cavity at the hilu m, were found to vary in depth of penetration from granule to granule. Most , but nor all, channels spanned the entire granule matrix, from the outer s urface to the central cavity. Under slight swelling conditions (water), cav ities swelled somewhat closed, while channels appeared to remain open. Swel ling also affected the permeability of the granule matrix to dye molecules. Penetration of an aqueous dye solution occurred primarily from the central cavity outward and laterally from channels. Even under the slight swelling conditions, colloidal gold particles filled channels and cavities, showing that they are voids. (C) 2000 Elsevier Science Ltd. All rights reserved.