Effects of Ɑβ+ω1,2‐gliadin and Ω5‐gliadin on Retrogradation of Wheat Amylose/Amylopectin

AbstractTwo gliadin components of ɑβ+ω1,2‐gliadin and ω5‐gliadin are isolated and their addition on retrogradation of wheat amylose and amylopectin are investigated by solid 13C NMR, IR, X‐ray diffraction, DSC and DC. The addition of ɑβ+ω1,2‐gliadin greatly enhanced the 72‐h retrogradation rate of wheat amylopectin from 5.74% to 10.43%. Two gliadins has no apparent influence on the retrogradation rate of wheat amylose. Dynamics of starch retrogradation indicated that nucleation exponent of wheat amylopectin increased greatly upon the addition of ɑβ+ω1,2‐gliadin component. The typical V‐type crystal (2θ° 7.7°, 13.2°, 20.1°) of wheat amylopectin and αβ+ω1,2‐gliadin component is present in retrograded wheat amylopectin, which indicated the direct way for using gliadin to promote wheat starch retrogradation. The DSC and DC results indicated that easy nucleation has been enforced by interaction of wheat amylopectin and αβ+ω1,2‐gliadin, and conformation conversion of β‐sheet into α‐helix and β‐turn occurred during retrogradation. The mechanism for the effects of αβ+ω1,2‐gliadin on the enhancement of wheat amylopectin retrogradation is deduced. The findings in the paper suggested a new way to increase starch retrogradation rate via interaction of amylopectin and αβ+ω1,2‐gliadin. Such a complex is found to be potentially a new kind of resistant starch with high quality.