Chemistry and Interactions of Seed Galactomannans

This chapter discusses the interaction of galactomannans with other polysaccharides. The general chemistry of the galactomannans has been reviewed by Whistler and Smart and others. The chapter discusses the uses of guar and locust-bean gums in various industrial applications and investigates the structural chemistry of galactomannans, especially as revealed by enzymic studies. Mixtures of locust-bean gum with the non-gelling polysaccharide from Xanthomonas campestris have been shown to interact synergistically to give firm, rubbery gels, whereas the use of the galactomannan from C yamopsis tetragonolobus (guar gum) results only in viscosity enhancement. These interactions are important in many of the industrial applications of galactomannans, and a study of them may also help provide an understanding of the associations among polysaccharide chains, contributing to biological cohesion and texture. The two main groups of galactomannan polysaccharides are those derived from (1) the endosperm of plant seeds, the vast majority of which originate in the Leguminoseae, and (2) microbial sources, in particular, the yeasts and other fungi. D-Mannose and D galactose are also found in numerous other plant polysaccharides—for example, glucomannansm, mannans, and galactans.