Extraction, purification and physicochemical characterization of fenugreek gum

Abstract

Fenugreek gum was extracted from defatted, deactivated fenugreek seeds (produced in Canada) at 10 °C for 2 h to give a yield of 22% with only 2.36% protein contaminates. Further purification of fenugreek gum was achieved by treating the gum solution with pronase to reduce the protein contaminates to 0.57%. High performance size exclusion chromatography showed that the enzyme treatment did not affect the molecular weight of the galactomannans. Monosaccharide and methylation analysis suggested that the extracted fenugreek galactomannans were highly substituted and the ratios of galactose to mannose were from 1.00:1.02 to 1.00:1.14. Although fenugreek gum exhibited higher molecular weight compared to locust bean gum and guar gum, the intrinsic viscosity and rheological behavior of fenugreek gum were reduced. This was attributed to the influence of the substitution patterns of the galactose on the mannosyl backbone chain. The purified fenugreek gum demonstrated less surface activity compared to the unpurified gum, which is in contradiction with the results reported in the literature. Detailed structural characterization of fenugreek gum has been done in order to elucidate the structure–functionality relationship of this gum and it will be reported in a subsequent paper.