RHEOLOGICAL STUDIES OF WATER-SOLUBLE (1-3),(1-4)-BETA-D-GLUCANS FROM MILLING FRACTIONS OF OAT

We studied the theological properties of water-soluble, mixed-linkage beta-glucans of high purity (88-99.5%) isolated from oats. Comparing t he beta-glucan fractions at the same concentration (1.3 mg/g) the mean value of the bran fraction viscosities was larger (by 5X) than the me an viscosity of endosperm fractions. Both mean values had a relative s tandard deviation of approximate to 20%. Heat treatment of oats did no t alter the viscous properties of the extracted beta-glucans. Activati on energies for the bran fraction at two shear rates were E(gamma=5.81 ) = 42 kJ/mole and E(gamma=5.81) = 17 kJ/mole. The variation in G' and G'' with frequency for the beta-glucan from bran fractions could be q ualitatively described by a superposition of two single Maxwell models with widely different relaxation time. These data can help predict po tential processing effects on such fractions incorporated as food comp onents.