Abstract
Starch granules were prepared from three kinds of Azuki beans (Vigna angularis ): Akanedainagon (dainagon), Erimoazuki (Erimo) and Shiroazuki. The properties of the starch granules were examined. The results obtained were as follows: 1) The mean particle sizes of the Dainagon, Erimo and Shiroazuki starches as determined by videomicrometer were 39.3, 38.0 and 37.5, um for long axis, and 32.4, 31.8 and 29.5, um for short axis, respectively. 2) The initiation temperature for gelatinization of Erimo starch by differential scanning calorimetry, photopastegraphy and Brabender's amylography (6 and 8 % starch suspensions) tended to be higher than the respective values of the other two starches. 3) The breakdown of Shiroazuki starch as determined by Brabender's amylography (8%) was 271 BU, which was relatively lower than the respective values of the other two starches. 4) The apparent amylose contents of the Dainagon, Erimo and Shiroazuki starches as determined by amperometric titration were 29.0, 27.4 and 28.7%, respectively, and those by the enzyme-chromatographic method were 30.4, 28.8 and 31.2%, respectively. The amylose content of Erimo starch was lower than that of the other two starches. 5) X-ray diffractograms of the Azuki bean starches showed Cb type patterns. 6) The susceptibility of Dainagon and Shiroazuki starch granules to a-amylase of the porcine pancreas was similar to that of normal maize starch granules, having relatively high susceptibility, and that of Erimo starch granules was lower than the respective values of the other two starches. By scanning electron microscopy (SEM), a stripe structure on the Azuki bean starch granules was observed following attack by pancreatin.
