Rheological properties of inulin-waxy maize starch systems

The rheological properties of mixed systems of inulin and waxy maize starch (WMS) were studied, as a model of carbohydrate-carbohydrate interactions in foods. Steady shear and oscillatory rheological properties were analyzed using a strain-controlled rheometer. Steady shear data were satisfactorily fitted to the Carreau model. The data were also fitted to the Herschel-Bulkley model. Concentrated inulin gels presented static and dynamic yield stresses. Phase inversion from a WMS-continuous system to an inulin-continuous system, manifested as a sudden change in rheological properties, was observed in samples with a total polymer concentration greater than or equal to30% (w/w, w.b.). In order to validate the oscillatory rheological data, some samples were subjected to stress relaxation experiments and both types of data were compared, showing a satisfactory agreement. The Cox-Merz rule, which relates steady shear and dynamic material functions, was not followed by most of the samples. An extended Cox-Merz rule was applied to the analysis of concentrated inulin gels. (C) 2002 Elsevier Science Ltd. All rights reserved.