Starches from different botanical sources I: Contribution of amylopectin fine structure to thermal properties and enzyme digestibility

Abstract

Fifteen starches from different botanical sources were selected to study the influence of structural features on thermal properties and enzyme digestibility. Morphological appearance, X-ray diffraction pattern, apparent amylose content, unit-chain length distribution of amylopectin, thermal properties and enzyme digestibility of starch varied with botanical source. It was demonstrated that the distribution of unit-chains of amylopectin significantly correlated with functional properties of the starches. Gelatinization temperature of native and retrograded starches decreased and increased with a relative abundance of unit-chains with an approximate degree of polymerization (DP) of 8–12 and 16–26, respectively (P<0.01). Similar unit-chain lengths also affected the enzyme digestibility of starch granules (P<0.01). Keywords: Starch; Amylopectin; Degree of polymerization; Gelatinization; Retrogradation; Enzyme digestibility