Gel formation in amidated low methoxyl pectin systems at unusually acidic conditions

A sample of amidated low methoxyl pectin was purified and recovered as the sodium salt form. Viscosity measurements were performed in 0.1 M NaCl at 20 degrees C. Tthe intrinsic viscosity and the critical overlapping concentrations were determined. Gel formation was investigated at acidic conditions. A phase diagram was established at pH 2, as a function of calcium ion and polymer concentrations, The mechanical properties of acid gets were determined as a function of the calcium ion concentration. Although the presence of calcium is necessary to obtain strong acid gels that can support their own weight, increasing calcium concentrations lead to heterogeneous gels.