SIZE DISTRIBUTION OF STARCH GRANULES IN MATURE BARLEY KERNELS

Starch constitutes 60-64% of barley grains, and occurs in the form of granules which range in size from 1 to 48 mu m in diameter and traditi onally are considered to fall into two major size classes. The objecti ve of this study was to investigate starch granule size distribution i n mature kernels of Alexis, Condor and Excel barley cultivars. A nonli near least square curve fitting technique was used to study granule di ameter distributions. The curve fitting procedure revealed a trimodal distribution of starch granules, characterized by three Gaussian curve s, indicating three classes of granules, A, B and C. The A granule dis tribution was distinct from B and C granule distributions, while there was substantial overlap between B and C granule distributions. On ave rage, A granules were characterized by a curve with peak center at a d iameter of 18.68 mu m, while B and C granules had peak centers at 2.60 mu m and 1.42 mu m, respectively. AI B, and C granules were 9.4%, 75. 3% and 15.3% of the total number of granules, respectively. These resu lts suggest the existence of three classes of starch granules rather t han the widely accepted two classes.