Fenugreek Galactomannans as Food Emulsifiers

Abstract

Fenugreek gum was extracted from fenugreek seeds and evaluated for its surface activity. This unique galactomannan has a mannose backbone grafted with galactose units at an average ratio of one. The purified fenugreek gum was found to reduce surface tension to values lower than guar gum (42 and 55 mN/m, respectively). The interfacial activity was surprisingly better than other galactomannans (interfacial tension was reduced to 2 mN/m in vegetable oils) which led to the formation of oil-in-water emulsions with small droplet size (2–3 μm) and long-term stability. The fenugreek gum was found to adsorb (or ‘precipitate’) on the oil interface forming a relatively thick interfacial film. The emulsions are more stable than any equivalent emulsions stabilized by other galactomannan gums. No flocculation was observed in emulsions stabilized with fenugreek concentrations sufficient for a good coverage of the oil interface as expressed by the coverage index (Rc) correlated to the gum/oil weight ratio (Rc>12).