The physicochemical properties of partially digested starch from sprouted wheat grain

Partially digested starch from grain heavily damaged by sprout-induced α-amylase was obtained by significantly delaying the harvest date using three wheat cultivars, Harunoakebono (HA), Haruyutaka (HY), and Hokushin (HS). In this investigation, the damaged starch was tested for physicochemical properties. The swelling power and peak viscosity determined by using a Rapid Visco-Analyzer decreased, and the digestibility of raw starch by glucoamylase increased as a result of an extremely late harvest except for HA, a sprouting-tolerant cultivar, in which visible sprouting was not seen even in the case of an extremely late harvest. However, an extremely late harvest did not significantly affect the amylose content, mean granule size, thermal properties determined by differential scanning calorimetry, and distributions of amylopectin chain length in HS and HY. Furthermore, observations by scanning electron microscopy indicated that HS and HY at an extremely late harvest contained a small amount of porous starch granules.