Water diffusion in chemical and physical polysaccharidic gels

Diffusion of water is a major interest in many food and biotechnological applications. In this work we determined the self-diffusion coefficient of water and sugars in chemical and physical polysaccharidic gels, by low field nuclear magnetic resonance. The physical gels were obtained from agar powder (gelagar type R, B&V, Parma Italy) with a final polymer concentration ranged between 0.2 and 1% (m/v). The chemical gels were synthetized from carboxymethylcellulose crosslinking with epichlorhydrin and PEG. All the materials were characterized by their rheological properties both by means of small amplitude oscillatory measurements and large deformation measurements with puncture test and uniaxial compression. Structural informations about the matrix, like the average pore size, can be obtained from self-diffusion coefficient of water.