Possibility of crosslinking of raw xanthan with divalent and trivalent metal ions

Sa？etak Biopolymers are biodegradable, biocompatible and non-toxic natural compounds with large molecular masses. Xanthan is a biopolymer produced by bacteria of genus Xanthomonas. Nowadays scientists are focused on examining the possibilities of crosslinking of xanthan using different agents. The aim of this paper was to investigate the possibility of crosslinking of xanthan with divalent and trivalent metal ions. During these studies, xanthan produced by reference strain Xanthomonas campestris ATCC 13951 on medium based on wastewater from white wine production was used. Xanthan solutions of different concentrations (1.0%, 2.0% and 2.5% (w/v)) were prepared in 0.1M sodium chloride. Salts of barium, calcium, magnesium, manganese, zinc, lead, as well as divalent and trivalent iron at different concentrations (0.025 M, 0.050 M and 0.075 M) and pH values (3, 5, 7 and 9) were used. The obtained results indicate that the success of crosslinking and the stability of the formed structures highly depend on the pH value of the salt solutions and the biopolymer concentration. The most stable, solid structures were formed by dropping 2.5% xanthan solution into a 0.075 M solution of FeCl3 at highly acidic pH value. The dry matter content of structures was 2.37%, and average dimensions were about 4.02 x 5.08 mm