Physicochemical property of Huaishan (Rhizoma Dioscorea) and Matai (Eleocharis dulcis) starches

The physicochemical properties of starch, the main component in tuberous ro ot of Huaishan (Rhizoma Dioscorea) and corm of Matai (Eleocharis dulcis) wa s investigated and compared with those of a Japanese yam, "Yamanoimo" starc h, and potato starch. Mean particle sizes of Huaishan and Matai starches we re 24 +/- 5 mu m and 12 +/- 5 mu m, respectively. X-Ray diffraction pattern suggests that Huaishan starch was B-type or C-type just close to B-type an d Matai starch was A-type or C-type just close to A-type. Apparently, the i ntermediate component (IntCom) of Huaishan starch, which was obtained by fr actionation of the starch into amylose and amylopectin, may still contain a mylose and amylopectin. IntCom of Matai starch has an intermediate nature b etween amylose and amylopectin. It is concluded that the amylopectin molecu les of Huaishan starch contain a larger amount of longer branched chains an d those of Matai starch contain a larger amount of shorter branched chains. Amylograms of Matai and Huaishan starches suggest that the gelatinized sta rches are difficult to retrograde. Digestibility of Huaishan starch by an a lpha-amylase was the highest among the tested starches.