Eastman and Moore' recently developed a new process for preparing granular, cold-water-soluble (P.c.w.s.) starch by high-temperature treatment of native starch with aqueous alcohol. G.c.w.s. starch has the desirable property of pasting withqut heating. This property provokes questions regarding the change that has occurred within the granule. The present communication reports data to help answer that question.
Scanning electron micrographs showed that g.c.w.s. corn and wheat starches retained their granular structure, but the granules were slightly misshapen. When viewed with a light-microscope under crossed Nicol prisms, g.c.w.s. starch displayed a strong birefringence without any discernable pattern. This was different from the birefringence of native starch, which exhibited the characteristic Maltese cross. The loss of the Maltese cross indicated destruction of the or&ring of crystallites in the native granules.
An X-ray diffraction pattern of g.c.w.s. corn starch was taken with Cu,Ni-foilfiltered, I&Y radiation (see Fig. 1A). Operation was at 35 kV and 18 mA. Peaks appeared at 28 = 13.0 and 20.1', which were equivalent to d-spacings of 6.80 and 4.42 A, respectively. This diffraction pattern is similar to that obtained2 for the hydrated, V-amylose structure with hexagonally close-packed helices spaced 13.6 W apart. The peaks at 28 -16 and 23', typical of native corn starchj, were not present.