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Title: PREDICTION OF THE NONLINEAR TRANSIENT AND OSCILLATORY RHEOLOGICAL BEHAVIOR OF FLOUR SUSPENSIONS USING A STRAIN-SEPARABLE INTEGRAL CONSTITUTIVE EQUATION

Author
item Carriere, Craig
item Thomas, Andrew - Aj
item Inglett, George

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: With the depressed prices for many agricultural materials today, the introduction of agricultural products into new markets and applications is essential to growth of the industry. In addition, the expansion of present market applications is also a viable vehicle to increase utilization of depressed agricultural commodities. In order to introduce these materials into new applications, a detailed understanding of the performance of these bio-based materials needs to be obtained. The effective production of new, application-targeted materials in a cost-effective manner requires an understanding of the flow and processing behavior of the materials to be developed. This work presents some of the initial research at characterizing the flow behavior of flour suspensions that are used currently in numerous food applications. Models for the flow behavior have been developed and evaluated. These models can be used in optimizing processing conditions to reduce production costs and predicting the performance of these materials in future applications. The work is continuing with more complicated bio-based blends.

Technical Abstract: The evaluation and development of validated models for the nonlinear viscoelastic (VE) behavior of materials is an important area of research which has impact on a number of industrial processes, including those in the food industry. Various nonlinear VE models have been developed over the years and evaluated for petroleum-based polymers; however, our understanding of the nonlinear VE behavior of biopolymers of industrial import lags our understanding of synthetic polymers. In the work reported herein, the nonlinear VE behavior of defatted oat flour, oat bran, barley flour, and oat flour suspensions was investigated. The rheological properties were measured using a Rheometrics Series IV controlled-strain rheometer equipped with a cone-and-plate fixture. The measurements were conducted at 23 +/ 0.5 deg C. The rheological data were interpreted using a strain separable K-BKZ type (Wagner) model with a damping function evaluated from stress relaxation data. The Wagner model was found to provide an accurate description of the rheological behavior of the suspensions produced from defatted oat flour, barley flour, and oat bran. For suspensions produced from oat flour, the model predictions deviated from the experimental data to a greater degree than the other materials.