Physicochemical Properties of Starches from Purple and Orange Fleshed Sweet Potato Roots at Two Levels of Fertilizer

Abstract

Abstract 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, digestibility by glucoamylase, X‐ray diffraction pattern, amylopecin chain distributions, and gelatinization properties by rapid visco analyzer and differential scanning calorimetry, were observed among these cultivars. On the other hand, higher application of NPK‐fertilizer had little impact on the starch properties. Thus, it was demonstrated that a key factor in altering starch characteristics in the case of sweet potato roots was the difference in cultivars, not the level of fertilizer.