Texture profile and turbidity of gellan/gelatin mixed gels

Abstract The effect of gellan (1.6–0.2%) to gelatin (0–1.4%) ratio and calcium ion concentration (0–30 mM) on the textural properties and turbidity of gellan/gelatin mixed gels was examined using instrumental Texture Profile Analysis (TPA) and spectrophotometry. Hardness of the mixed gels decreased as the proportion of gellan decreased. Hardness increased with increasing calcium ions until calcium concentration reached a critical level, after which further increases in calcium resulted in a reduction of hardness. Brittleness, springiness and cohesiveness were very sensitive to low levels of added calcium (0–10 mM), but less sensitive to higher calcium concentrations and gellan/gelatin ratio. In general, the addition of calcium ions caused gels to be more brittle and less cohesive and springy. Decreasing gellan to gelatin ratio caused an increase in gel turbidity at lower calcium ion levels (2–4 mM) and a decrease in turbidity at high calcium levels (20–30 mM). Maximum turbidity was observed in 0.6% gellan–1.0% gelatin gels without added calcium. The results of this study suggested a weak positive interaction between gellan and gelatin when no calcium was added, whereas at higher calcium levels gellan formed a continuous network and gelatin a discontinuous phase.