QENS investigation of the dynamics of starch saccharides

Abstract

We present here quasi-elastic neutron scattering results on D₂O hydrated samples of amylose, one of the main saccharide components of starch. Two different sample hydrations (h = 0.5 and 1.0 g D₂O (g dry amylose)⁻¹ have been investigated in the temperature range 170 to 350 K. Below 260 K only an elastic contribution is present in the spectra, while a quasi-elastic component shows up above this temperature. The elastic incoherent structure factor (EISF) associated with this component changes considerably with increasing temperature. For the sample with hydration h = 0.5 the confinement volume increases by a factor of four in going from 300 to 350 K, and the proportion of hydrogen involved in the confined diffusion motion increases as well from 30 to 55%. Similar effects are observed at the higher hydration investigated. The observed dynamics can be associated with the known plasticising role of water in polysaccharides.