Influence of the acetyl substituent on the interaction of xanthan with plant polysaccharides — I. Xanthan-locust bean gum systems

Abstract

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 locust bean gum (LBG) in de-ionized water and the data were analysed statistically. The majority of the polymers interacted to form a strong thermoreversible-gel network, and the strength of the system was shown to be heavily dependent on the level of acetyl substitution. A polymer from a mutant strain of X. campestris, believed to lack the terminal mannose residue from the trisaccharide side-chains, formed an exceptionally weak gel network, suggesting that the xanthan side-chain may play an important role in the interaction with LBG.