Rheology and gelation of water-insoluble dextran from Leuconostoc mesenteroides NRRL B-523

Abstract

Dynamic oscillatory testing has been used to study the rheology of water-insoluble dextran. The rheological properties (storage and loss moduli) of dextran gel were measured and dextran was found to be neither a strong gel nor a weak gel, but an entanglement network at a concentration of 250 mg/ml. The extent of gelation, illustrated by the gel elastic modulus G', is found to decrease with increasing concentration of calcium ions. This was confirmed by shift of crossover frequencies towards higher values on the dynamic spectra and lower yield stress tau values obtained from stress ramp experiments. Finally, a comparison between gelation of dextran and alginate (a similar biopolymer) was made for clear understanding of effect of calcium ions on the dextran gelation. (C) 2003 Elsevier Ltd. All rights reserved.