Pectate concentration determination

The rheological behaviour in the range of LM pectin was analyzed and the sol-gel diagram established [59] for different stoichiometric ratios. In their paper, these authors determined the gel times for sodium pectate during calcium-induced gelation and the variation of the gel time with polymer concentration, stoichrometric ratio and temperature. 

Figure 3. Determination of the optimal parameters of PelZ activity. A pectate lyase activity in a reaction medium containing PGA 0.05%, CaCl2 0.2 mM and Tris-HCl 50 mM at various pH. B pectate lyase activity in a reaction medium containing PGA 0.05%, Tris-HCl 50 mM pH 8.5 and increasing concentrations of CaCl2- C pectate lyase activity in a reaction medium containing CaCl2 0.2 mM, Tris-HCl 50 mM pH 8.5 and as substrate either PGA 0.05% or pectins 0.05%, with different degrees of methylation (from Copenhagen Pectin).

The various groups of pectic substances are usually characterized by their solubility behavior. Polygalacturonides, like other polyuronides, can be quantitatively estimated by the amount of carbon dioxide formed upon heating with hot acid. Pectic substances of all sorts have been commonly determined by the formation and weighing of water-insoluble pectic acid or calcium pectate but unfortunately it is difficult to get these precipitates free from impurities (particularly other polysaccharides) present in the material analyzed. Today, the most common method of estimation is the spectrophotometric measurement of the colored complex formed upon the addition of alcoholic carbazole to the material to be analyzed after alkali treatment and heating with concentrated sulfuric acid. ... 

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