Synergistic interaction of xanthan gum with glucomannans and galactomannans

Abstract

Xanthan gum forms thermoreversible gels when mixed with konjac mannan or locust bean gum. The stronger gels are formed with konjac mannan and the maximum gel strength for the mixed systems in the absence of electrolyte occurs at a xanthan-konjac mannan or xanthan-locust bean gum mixing ratio of about 1:1. In the presence of 0.04 mol/dm 3 NaCl the optimum mixing ratio is unchanged for xanthan-locust bean gum blends but changes to about 2:1 for xanthan-konjac mannan blends. These observations support differential scanning calorimetric data which are able to monitor both gelation and the conformational transition of the xanthan molecules and indicates that (i) in the absence of electrolyte konjac mannan interacts with disordered xanthan chains whilst in the presence of 0.04 mol/dm 3 NaCl it interacts with ordered xanthan chains, and (ii) locust bean gum interacts with ordered xanthan chains both in the presence and absence of electrolyte.