Effects of alpha beta+omega 1,2-Gliadin and omega 5-Gliadin on Retrogradation of Wheat Amylose/Amylopectin

摘要

Two gliadin components of alpha beta+omega 1,2-gliadin and omega 5-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 alpha beta+omega 1,2-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 alpha beta+omega 1,2-gliadin component. The typical V-type crystal (2 theta degrees 7.7 degrees, 13.2 degrees, 20.1 degrees) of wheat amylopectin and alpha beta+omega 1,2-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 alpha beta+omega 1,2-gliadin, and conformation conversion of beta-sheet into alpha-helix and beta-turn occurred during retrogradation. The mechanism for the effects of alpha beta+omega 1,2-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 alpha beta+omega 1,2-gliadin. Such a complex is found to be potentially a new kind of resistant starch with high quality.