Effects of Deacetylated Konjac Glucomannan on the pasting, rheological and retrogradation properties of wheat starch

The heat inwlerame and tetrogradation h; havior of native whea. starch tWS) aren desi iota able tor .,.arch based gel roods. therefore the coatbinations of WS and hl droccollo.ds have attraccted entensive attentions. he objectives of this study were to investigate the effects of konjac glucornannan (KGM) with different degree of deacetylation ( )D/ on the pasting, rheological and retrogradation properties of WS. Results showed that deacetyl-konjac glucomannan (DKGM) increased the peak viscosity (PV), trough viscosity (TV) and final viscosity .FV), while decreased the breakdown (BD) values of WS, suggesting the enhancement of the viscosity and thermal stability of WS paste. The raised storage modulus (G') of WS gels with DKGM1 (DD, 48.23%) demonstrated that the partial removal of acetyl groups from KGM chains effectively promoted the fonnation of gel network, accompanied by increased elasticity. After stming at 4 degrees C for 7 days, the hardness of gels increased up 369%, while supplement with DKGM significantly (p < 0.05) decreased the hardness. fhese data demonstrated that DKGM delayed the process of starch retrogradation, which was Miter verified by LF-NMR analysis. Besides, the addition of DKGM reduced the retogradation nate, relative crystallinity and the orderliness of WS-DKGM gels with the prolonging of storage at 4 `C, all validating the hindrance of starch retrogradation by DKGM. Therefore, these data suggested that panial deacetylation of KGM could effectively improve the pasting, rheological characteristics and impede the retrogradation of WS.