Abstract: The effects of low acyl (LA) gellan gum concentration, the ratio of glucono-δ-lactone (GDL) to LA and acid immersion on the properties of low acyl gellan gum gels formed by acidification with GDL were investigated. The gelation profile of low acyl gellan gum after the addition of GDL showed a gradual decrease in pH, and the higher the GDL/LA ratio was, the lower the pH of the mixed system was and the higher the acidification rate. LA gellan gum concentration and GDL/LA ratio had a pronounced effect on the structure of the gels. Fracture stress and water-holding capacity increased first and then declined with the increase in GDL/LA ratio. Higher LA gellan gum concentration led to larger fracture stress and opacity index. Moreover, the fracture strain decreased with the increase in GDL/LA ratio. The opacity index increased while fracture strain decreased with increasing GDL/LA ratio. Acid immersion at pH 1 had no impact on the strength of the gels with GDL/LA ratio of 2:1 and 4:1, while for those with GDL/LA ratio of 1:4, 1:2 and 1:1, the gel strength increased with increasing immersion time, suggesting restructuring of the gels.

Key words: low acyl gellan gum, acid gelation, gelling property, fracture stress, fracture strain