PHYSICOCHEMICAL PROPERTIES OF STARCHES FROM PURPLE AND ORANGE FLESHEDSWEET-POTATO ROOTS AT 2 LEVELS OF FERTILIZER

Starch was extracted from purple (Ayamurasaki and Kyushu No. 109) and orange (Kyushu No. 120 and Kyushu No. 122) fleshed sweet potato roots at two levels of NPK-fertilizer. The physicochemical properties of the isolated starches were compared. Differences in the starch properties , namely average granule size, amylose content, phosphorus content, di gestibility by glucoamylase, X-ray diffraction pattern, amylopecin cha in distributions, and gelatinization properties by rapid visco analyze r and differential scanning calorimetry, were observed among these cul tivars. On the other hand, higher application of NPK-fertilizer had li ttle impact on the starch properties. Thus, it was demonstrated that a key factor in altering starch characteristics in the case of sweet po tato roots was the difference in cultivars, not the level of fertilize r.