Abstract: Low acyl gellan gum (LAG) fluid gels were prepared via heat-induced gelation of LAG solution under controlled temperature and shear conditions, and their properties were evaluated with respect to gellan gum concentration, cooling rate, shear rate, ion type and concentration, and glucono-δ-lactone (GDL). The microstructure of the gels was investigated as well. The results indicated that increased gellan gum concentration increased the transition temperature for the system, resulting in fluid gels with increased particle size, final viscosity and irregularity. When the cooling rate exceeded the critical value for the gel system, the transition temperature substantially remained unchanged. The critical cooling rate declined with increasing gellan gum concentration, decreasing from 9 to 4 ℃/min when gellan gum concentration increased from 0.005 to 0.015 g/mL. The transition temperature and the final viscosity and particle size of fluid gels increased with increasing ion concentration. Ca2+ led to a higher final viscosity than did Na+. The higher GDL concentration resulted in higher transition temperature and higher viscosity and looser texture of fluid gels.

Key words: gellan gum, fluid gel, shear rate, cooling rate, microstructure