Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 9, 1999
Publication Date: N/A
Interpretive Summary: 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 products 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-based systems. Increase in the level of soluble oat fiber in the blends was found to exhibit unexpected increases in the thickness of the solution. These increases in solution thickness are of importance in the development of cost-effective processing schemes for introducing oat-based fibers into new food products.
Technical Abstract: The rheological properties of several (1-3)(1-4)-beta-D-glucan/ amylodextrin blends designated as OATRIM were investigated. The experiments were conducted using a CarriMed CSL**2 500 controlled-stress rheometer with a cone-and-plate fixture (6-cm diameter, 4 deg cone). OATRIM containing 10% by weight (1-3) (1-4)-beta-D-glucan, was found to exhibit a region of shear-thickening behavior at 25 deg C above a critical shear rate of 30 s**-1. The shear-thickening behavior was also found to be dependent on the temperature of the solution with the magnitude of the observed shear-thickening region decreasing with temperature and finally being eliminated at a temperature of 60 deg C. When the level of (1-3) (1-4)-beta-D-glucan in the OATRIM sample was reduced to 5% by weight, the shear-thickening region was not observed. When the (1-3) (1-4)-beta-D-glucan level was increased to 24% by weight, two regions of shear thickening were observed with critical shear rates of 30 and 100 s**-1. In addition, a double stress overshoot was observed during the startup of steady-state shear at a shear rate of 100 s**-1. These observations indicate that the shear-thickening behavior is due, in part, to an interaction between the (1-3)(1-4)-beta-D-glucans and the amylodextrins that make up OATRIM.