Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups [more exactly: a (1-4)-linked beta-D-mannopyranose backbone with branchpoints from their 6-positions linked to alpha-D-galactose, i.e. 1-6-linked alpha-D-galactopyranose].

In order of increasing number of mannose-to-galactose ratio:

• fenugreek gum , mannose:galactose ~1:1
• guar gum, mannose:galactose ~2:1
• tara gum , mannose:galactose ~3:1
• locust bean gum or carob gum, mannose:galactose ~4:1

Galactomannans are often used in food products to viscosify the water phase.