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Solution Viscoelastic Properties of OATRIM-10 and Cooked Oat Bran

¹Biomaterials Processing Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, 1815 N. University Street, Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. E-mail: carriecj@mail.ncaur.usda.gov Phone: 309/681-6240. Fax: 309/681-6685 ³Biopolymer Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, Peoria, IL.

The solution rheological behaviors 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 0–250/sec. The shear-thinning behavior was reproduced during the measurement of a second thixotropic loop. In contrast, OATRIM-10 exhibited an unexpected region of shear-thickening behavior at 20–80/sec. 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 that is partially disentangled at higher shear rates. Subsequent 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 for cooked oat bran can be described reasonably well using a generalized linear viscoelastic (GLV) model. The oscillatory shear data obtained for OATRIM-10 could not be described by the GLV model. OATRIM-10 exhibited a distinctive plateau centered at 10/sec, and the low frequency response of storage modulus G′ decreased with a much larger slope in frequency than was predicted by the GLV model.