Adsorption-isotherm and effect of gum blends on viscosity and microstructure of oat gum (beta-D-glucan)

Interactions of oat beta-glucan/oat gum (OG) in binary mixtures with other gums [xanthan (XG), locust bean (LEG), and guar (GG)] were studied by viscometry at ratios (50/50, 60/40, and 50/20) and concentrations (0.5 and 0.75%). Physical structure changes due to interactions were examined by scanning electron microscopy (SEM). Equilibrium moisture contents (EMC) were observed at relative humidities (RH), 10.5%, 22%, 33%, 44%, 76% and 93%. Water and oil uptake were determined. Viscosity enhancement occurred in OG/LBG (50/50 and 60/40; 0.5%) and OG/XG (60/40; 0.5%) blends, suggesting synergism. Micrographs depicted microstructural homogeneity (single bulk phase) in OG/LBG and OG/XG blends. EMC of OG and GG were 26.1 and 31.6%, respectively, at 93% RH for 2 wk. LBG showed high mold growth at 93% RH. Uptake of water and oil by OG were 2.6 and 2.0 mL/g, respectively.