Determination of galactomannan (gum) in guar (Cyamopsis tetragonolobus) by high performance liquid chromatography

Abstract A method is described for analysis by HPLC of galactomannan (gum) in seed of guar ( Cyamopsis tetragonolobus (L) Taub). The dry seed is ground in 950 ml litre −1 ethanol, and free sugars are removed by ethanol extract; the seed residue is hydrolysed with 2 M trifluoracetic acid in a pressure cooker (1 h at ˜ 105 kPa). Hydrolysing the gum in situ avoids the problems common with other techniques of extracting different fractions of gum, each having different mannose: galactose ratios. The method serves as a simple measure of gum contents in guar, and up to 20 samples per day can be processed.