Gelling properties of gellan solutions containing monovalent and divalent cations

Gelling temperatures of gellan solutions with the addition of Na+ and K+ ranging from 15 to 450 mM or Ca++ and Mg++ from 2 to 40 mM were determined by dynamic rheological testing at four polymer concentrations between 0.4 and 2.0% (w/w). Gelling temperatures were much higher for gellan solutions containing divalent cations than for those containing the same amount of monovalent cations. Solutions containing K+ gelled at higher temperatures than those containing Na+. Effects of Ca++ and Mg++ on gelling temperatures were not significantly different. A general model was developed to predict the gelling temperature of gellan solutions as functions of cation and polymer concentrations.