Studies on the Relationship Between Water‐satured State and Crystallinity by the Diffraction Method for Moistened Potato Starch

Abstract Crystallinity was measured by X‐ray diffraction method and water‐saturated state was determined by means of the moisture contents calculated from the crystallinity for moistened cellulose and potato starch. In the X‐ray diffractograms the upper areas which were separated by the straight line joined the points of intensity at 37° and 4° (8°) of diffraction angle was the relative reflection area in the crystalline and amorphous portions, and the lower area was the background of the non‐relative reflection area. The upper area separated by the smooth curve joined the minimum intensity at 4° to 37° of diffraction angle corresponded to the crystalline portion and the lower area to the amorphous one. The ratio of the crystalline portion to sum of the crystalline and amorphous portions was considered to be crystallinity. Crystallinity of the air‐dried and the moisture‐saturated (28%) samples of cellulose were 0.68 and 0.71, resp. The crystallinity of the air‐dried and water‐saturated (49%) samples of potato starch were 0.24 and 0.32, resp.