INFLUENCE OF THE ACETYL SUBSTITUENT ON THE INTERACTION OF XANTHAN WITH PLANT POLYSACCHARIDES .3. XANTHAN-KONJAC MANNAN SYSTEMS

A range of xanthans (Na+ salt form) with varying levels of acetyl and pyruvic acid substitution were prepared by culturing different strains of Xanthomonas campestris and by chemical deacetylation and depyruvylation. Oscillatory-shear measurements were used to characterize the interaction between these polymers and konjac mannan in de-ionized water and the data was analysed statistically. The majority of the polymers interacted to form a strong thermoreversible-gel network. Xanthan gelled with konjac mannan only at relatively high concentrations compared with xanthan-locust bean gum (LBG) systems but the gels formed had significantly higher melting and setting temperatures than xanthan-LBG gels of the same concentration. The transition from the liquid to the gel state was also much sharper. The strength of the gels was shown to be heavily dependent on the level of acetyl substitution. © 1990.