SYNERGISTIC INTERACTION BETWEEN XANTHAN AND TARA-BEAN GUM

The non-Newtonian behaviour and dynamic viscoelasticity of a series of aqueous mixtures of xanthan and tara-bean gum were measured with a rheogoniometer. At a concentration of 0.2% of total gum, gelation did not occur at room temperature, but at a low temperature (0-degrees-C). A much stronger interaction was observed with mixtures containing deacetylated, deacylated, or native xanthan than with depyruvated xanthan. The maximum dynamic modulus was obtained when the ratio of xanthan to tara-bean gum was 1:2. The dynamic viscoelastic parameters for mixtures with deacetylated and deacylated xanthan decreased rapidly at temperatures above 25 and 20-degrees-C, respectively. It was concluded that the side chains of the tara-bean gum molecule prevent an intermolecular interaction between xanthan and tara-bean gum. The results obtained support the interaction mechanism between xanthan and locust-bean gum previously proposed.