Fenugreek (Trigonella foenum graecum) gum: A functional ingredient with promising properties and applications in food and pharmaceuticals—A review

Abstract

Fenugreek (Trigonella foenum graecum) is an annual plant belonging to the family Leguminosae or Fabaceae. The seeds of fenugreek contain 26.8% soluble fiber chemically identified as galactomannans with properties similar to soluble fiber of guar seeds and psyllium husk and so on. Galactomannans are biopolymers consisting of linear core poly (1,4)‐β‐D‐mannan backbone having varying degrees of D‐galactosyl substituents attached by 1,6‐glycosidic linkages. Different galactomannans derived from various legumes usually differ in molecular weight, ratio of mannose to galactose, and the mode and place of linkages of galactose moieties to the mannan backbone. Fenugreek gum has a galactose to mannose ratio of 1:1, showing the highest amount of galactose resulting in its highest water solubility compared with guar and locust bean gum. It suggested that the galactose and mannose moieties are linked uniformly in fenugreek gum resulting in maximum hydration and solubility. This M/G ratio affects the physicochemical properties of galactomannans and is inversely related to the solubility of gum. Galactomannans sterically stabilize the emulsions against flocculation and coalescence by getting adsorbed onto oil droplets. In addition to this, galactomannans are all found to exhibit some surface, interfacial, and emulsification activities. Because of these properties, it is preferred over other natural hydrocolloids as an excellent ingredient for various food applications. As a hydrocolloid, fenugreek gum provides texture, appeal, gelling, thickening, emulsifying, stabilizing, and encapsulating properties. In the present review, we summarized the extraction, purification, chemical, functional properties, molecular structure, thermal and rheological behavior of gum isolated from fenugreek seeds, and then vital application of this traditional source of hydrocolloids in food, pharmaceutical, and other industries.