| Provisco AG | |
| Waldkircherstrasse 7 | |
| CH-9213 Hauptwil, Switzerland | |
| Phone: | +41 71 422 66 55 |
| Fax: | +41 71 422 66 56 |
Xanthan
Sources and Extraction
Xanthan gum is produced by fermentation of glucose or saccharose solutions with pure cultures of xanthomonas campestris or phasaeoli. Due to the high viscosity of the xanthan produced, the glucose concentrate of the substratum must thereby not exceed 5%. The fermentation also requires a nitric source (yeast) as well as mineral nutriments and puffer salts. After completion of the synthesis, which takes about two days, the fermentation batch is pasteurised in order to destroy the micro-organisms, and by centrifugation is cleaned from cell particles. By adding isopropyl, the xanthan is dropped out from the diluted viscous solution. After filtration – or centrifugation – the product is dried and milled. The production requires equipments of great capacity and thus high investment costs. The annual production is estimated at approx. 1500 tons.
Properties
Composition
Xanthan is a long chained polysaccharide with a large number of trisaccharide side chains. The components D-glucose, D-mannose and D-glucuronic acid exist in the molar proportion of about 3:3:2. The main chain consists of β-(1-4)-linked D-glucose-units. The side chains are composed of two mannose units and one glucuronic acid unit. Approx. 4.7 % acetyl groups and 3.5 % pyruvic acid groups are also bonded to the side chains. The average molecular weights are about 1 000 000.
Solubility
Xanthan is easily soluble in cold and warm water. The viscosity of such solutions is neither considerably changed by increased temperature (up to approx. 90° C) nor influenced by pH, nor have high salt concentrations negative influence on the viscosity. Solutions are highly resistant against chemical and enzymatical degradation. Xanthan solutions show a very pronounced pseudo-plasticity.