Estimation of mixed linkage beta-glucan concentration in oat and barley from viscosity of whole grain flour slurry

The presence of beta-glucan from oat (Avena sativa L.) or barley (Hordeum vulgare L.) products in the human diet can lower serum cholesterol. The selection of new oat or barley cultivars with higher beta-glucan concentration in the grain is usually limited by the efficiency of the analytical procedure required to measure this component. The utility of flour slurry viscosity as an indirect means of estimating flour beta-glucan concentration was investigated. Water at 25 degrees C was added to enzyme-inactivated whole-grain oat flour to form a 23% dry matter mixture, and stirred to form a uniform slurry. Viscosity, as measured with a rotational spindle-type viscometer, increased hyperbolically with time. Viscosity measured 3 h after water addition was exponentially dependent on flour content and was linearly correlated with beta-glucan concentration in the flour. The procedure was useful as a screening method for the estimation of beta-glucan concentration in preliminary breeding lines of oat and barley. The procedure is effective with enzyme-inactivated (steam-treated) whole or dehulled grain, but the presence of endo-beta-glucanases in hulls of oats and barley prevent the application or this procedure with flours of raw whole oats and barleys.