C-13 CP MAS NMR-SPECTROSCOPY OF NATIVE AND ACID MODIFIED STARCHES

13 CP/MAS NMR spectroscopic studies of some starches from cereals (wheat, maize and finger millet), pulses (green gram, chick pea), tuber (potato) and root (tapioca), and their respective acid (HCl, HNO3) Modified starches were carried out. While cereal starches exhibited a triplet signal for their anomeric carbons, pulse, tuber and root starches showed doublets. Line width changes in signals indicated that debranching in the above modified starches led to narrowing of C6 signals (more pronounced in the case of potato and tapioca starches) and were consistent with the release of branching strains. Potato starch, both native and modified, was found to be different from other starches as inferred from the chemical shift values for their anomeric carbons and line shape. The dihedral angle (phi2') calculated from chemical shift values for C1 and conformation of dihedral angel (chi) as predicted from chemical shift of C6 are discussed with respect to structural organization.