Experiments on the "Ryokka" phenomenon in glutinous rice grains : (3) Electronmicroscopic investigation on the surface structure of starch granules

Abstract

It was investigated with electronmicroscope, how the surface structure of starch granules was affected by the different contents of water in grains. Materials used are shown in Table 1 and the following results were obtained. 1) In all the figures illustrated, it is shown that the starch granules have similar shape of the pentagonal dodecahedron, of which the diameter is 6μ in an average. The surface of starch granules is covered less distinctly with microgranules, notwithstanding water contents. 2) Fig. 1∼5 show the surfaces of glutinous granules with various water contents. The surface of the moist granules is of comparatively even structure in the cases of 22% (Fig. 1 & 2) and 19% (Fig. 3) of water contents. The most desiccated granules in which the Ryokka phenomenon is completed, however, have the very uneven surface with a noticeable feature, just like that of the pumice (Fig. 4 & 5). 3) Granules of non-glutinous starches, when, desiccated. are also more unevenly structured in the surface (Fig. 9) as compared with moist granules, such as 23% (Fig. 6 & 7) and 19 % (Fig. 8) of water contents. But the distinctive features mentioned above can not be recognized. Explanation of the plates Fig. 1&2 Glutinous granules, 22% of water contents Fig. 3 Glutinous granules, 19% of water contents Fig. 4&5 Glutinous granules, 8.7% of water contents Fig. 6&7 Non-glutinous granules, 23% of water contents Fig. 8 Non-glutinous granules, 19% of water contents Fig. 9 Non-glutinous granules, 9% of water contents