Diversity in amylopectin structure, thermal and pasting properties of starches from wheat varieties/lines.

Structural, thermal and pasting diversity of starches from Indian and exotic lines of wheat was studied. Majority of the starches showed amylose content ranging between 22% and 28%. Endotherm temperatures (T(o), T(p) and T(c)) of the starches showed a range between 56-57, 60 -61 and 65.5-66.5 degrees C, respectively. Exotherms with T(p) between 87.0 and 88.2 degrees C were observed during cooling of heated starches, indicating the presence of amylose-lipid complexes. Exotherm temperatures were negatively correlated to swelling power. Amylopectin unit chains with different degree of polymerization (DP) were observed to be associated with pasting temperature, setback and thermal (endothermic T(o), T(p), and T(c)) parameters. Amylopectin unit chains of DP 13-24 showed positive relationship with endothermic T(o), T(p) and T(c). Pasting temperature showed positive correlation with short chains (DP 6-12) while negative correlation with medium chain (DP 13-24) amylopectins. Setback was positively correlated to DP 16-18 and negatively to DSC amylose-lipid parameters.