Dynamics of hydrated saccharides of interest in food science

We have used IN13 at the ILL to investigate the dynamics of amylose and amy lopectine performing elastic scans from 20 to 320 K at different hydration levels. In the dry samples, the atomic dynamics is harmonic in the whole te mperature range explored. For the hydrated samples the mean square atomic d isplacement, [u(2)], is almost hydration independent and harmonic up to sim ilar to 230 K for amylose, and similar to 250 K for amylopectine. A 'glass- like' kinetic transition then shows up with a marked increase in [u(2)]: th is behaviour is qualitatively similar to that observed in other biopolymers like globular proteins, hut here the transition temperature is higher and it markedly varies with hydration. (C) 2000 Elsevier Science B.V. All right s reserved.