Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 23, 1998
Publication Date: N/A
Interpretive Summary: Oat bran and other oat materials are used in numerous food applications where high-fiber content is desired in food products. The soluble fiber of oats is acknowledged to benefit health by lowering blood cholesterol and reducing the risk of coronary heart disease. Despite the importance of oat bran in food applications, little is known about the flow properties of these materials. In order to process oat-based materials in a cost-effective manner, an understanding of the flow behavior needs to be developed. This work reports on some of the first research aimed at understanding the flow behavior of oat bran and OATRIM-10. OATRIM-10 was found to exhibit an unexpected rise in the solution fluidity. This rise in fluidity is of importance in any non-food application such as paint and could open new application areas for these materials.
Technical Abstract: The solution rheological behavior of OATRIM-10 and cooked oat bran were investigated. The rheological properties of the materials were investigated using both thixotropic loop and small-amplitude oscillatory shear experiments. The cooked oat bran exhibited shear-thinning behavior during a thixotropic loop experiment over a shear rate range of 0 to 250 s-**1. The shear-thinning behavior was reproducible during the application of a second thixotropic loop. In contrast, OATRIM-10 exhibited an unexpected region of shear-thickening behavior from 20-80 s-**1. The shear-thickening and subsequent shear-thinning regions for OATRIM-10 could be described by a transient network model indicating that the shear-thickening behavior is caused by a shear-induced entangled network which is partially disentangled at high shear rates. Repeated thixotropic loop experiments displayed the shear-thickening region for OATRIM-10 indicating that the network structure can be reformed during the imposition of a shear field. Small-amplitude oscillatory shear data indicated that cooked oat bran behaves as a random coil in solution. The oscillatory data for cooked oat bran can be described reasonably well using a bead-spring model with vanishing hydrodynamic interaction. The oscillatory data obtained for OATRIM-10 could not be described by bead-spring model predictions.