The effect of centrifugation on agar/sucrose gels

The viscoelascity and water mobility of 3% agar gels containing 5, 10 and 20% sucrose, before and after centrifugation, were studied by using dynamic mechanical spectroscopy and nuclear magnetic resonance relaxometry. Centrifugation was found to induce damage in the gel by phase separation of water. However, results suggest that water can recombine after centrifugation with closely packed macromolecules to provide a similar molecular structure to that of the gel before centrifugation. Sucrose helped reduce exudation of water at low centrifugation speeds through hydrogen bonding. The effects of centrifugation at high speed on water mobility were compensated by increasing sucrose concentration. Centrifugation created water compartments in the gel with distinct motion properties. On the contrary, sucrose concentration did not affect the hydraulic radius of these compartments. (C) 2002 Elsevier Science Ltd. All rights reserved.