Studies on oat gum [(1→3, 1→4)-β- D-glucan]: composition, molecular weight estimation and rheological properties

Abstract

Oat gum was extracted from oat bran and examined chromatographically for monosaccharide constituent, presence of glycoprotein and equivalent dextran molecular weight (EDMW). Protein and ash contents were also determined. The viscosity of oat gum was studied at variable pH, temperature and concentrations of salt and sucrose. Viscosity of oat gum was compared with that of other food grade gums (xanthan, guar, gum arabic, and locust bean). TLC analysis identified only glucose and showed no evidence of xylose, arabinose or glycoprotein in the oat gum extract. The gum was 98.4% glucose as determined by high performance liquid chromatograpy. The protein and ash contents were 1.3% (N × 6.25) and 0.30%, respectively. EDMW of the extracted gum was ~882 000. Viscosity of oat gum (0.5%) was stable over a wide range of pH (2–10), decreased with increased temperature and increased in the presence of sucrose (20–45%). Oat gum was less viscous than xanthan and guar at 0.5%, but slightly more viscous than locust bean gum at the same concentration.