30E-8 |
Synergistic effects of inulin and xanthan gum |
A. D. WESTPHALEN, Chemical Engineering, Iowa State University, Ames, IA 50011 and J. L. Briggs, Agricultural and Biosystems Engineering, Iowa State University, 1553 Food Science Building, Ames, IA 50011. Inulin is recognized for its neutraceutical effects. As a result, it has been incorporated into food products as an additional ingredient to enhance their health benefits. One such product is salad dressings. Considering the inclusion of xanthan gum in some low fat dressings, it was the objective of this study to evaluate the influence of inulin concentration on the rheological behavior of xanthan solutions. Xathan solutions at concentrations of 0.25 and 0.5% were prepared. Inulin was added at concentrations ranging from 0 - 20%. Rheological behavior was evaluated by rotational viscometry at 10 °C. Thixotropic characteristics were also quantified by conducting a shear rate up to 700 1/s and down to 0 1/s. All samples behaved as power law fluids. Each xanthan solution exhibited an increasing flow behavior index (n) with increasing inulin concentration, reaching a maximum, followed by a decline in n. This critical concentration was observed at 15 and 18% for 0.50 and 0.25% xanthan solution, respectively. The consistency coefficient (K) increased exponentially as the critical concentration of inulin was exceeded. K values were relatively constant below the critical inulin concentration. Degree of thixotropy increased up to 3-fold above the critical inulin concentration for both xanthan solutions. The significance of these results is that rheological properties remain relatively unaffected by inulin concentration below a critical value. Above this value, however, inulin and xanthan have a synergistic effect on the rheological behavior of these solutions. Understanding this relationship between inulin and xanthan is of value to product development and process design.
Session 30E, Food Engineering: Rheology and texture
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