Relationship of granule size distribution and amylopectin structure with pasting, thermal, and retrogradation properties in wheat starch.

Starches separated from 18 Indian wheat varieties were evaluated to see relationship of granule size distribution and amylopectin structure with pasting, thermal, and retrogradation properties. Average diameter of A-, B-, and C-granules among different starches varied between 23.0 and 28.5, 10.0 and 12.0, and 2.3 and 2.7 mum, respectively. Amylopectin chain length distribution varied significantly, short length chains (DP 6-12) and long length chains (DP > 24) ranged between 44.5 and 52.4% and 3.7 and 6.5%, respectively, whereas amylose content ranged between 18.2 and 28.8%. Short length chains of amylopectin had inverse relationship with starch gelatinization temperatures T(o), T(p), and T(c). Starches with higher crystallinity had higher enthalpy of gelatinization and lower swelling power. Paste characteristics were mainly dependent upon granule type and all pasting parameters except pasting temperature, showed significant positive correlations with A-granules and negative with the proportion of B- and C-granule.