Dielectric, thermal, and rheological properties of inulin/water binary solutions in the selected concentration

Abstract

AbstractInulin—a prebiotic has many applications in the food and pharmaceutical industries for texture modification and replacement of fat/sugar. In this study, thermal, rheological, and dielectric properties of inulin solutions were studied in a wide range of concentrations (5–50% w/v). Inulin is readily dissolved in water in low concentrations (< 20%), and exhibited Newtonian flow behavior, and the dielectric spectra were close to the pure water. The dielectric constant, ε′ of concentrated inulin (40–50%) showed frequency independency (500–1,150 MHz) whereas the loss factor, ε″ increased with frequency. Oscillatory rheology of concentrated inulin solutions at selected temperatures showed solid‐like behavior (G′ > G″), and the mechanical rigidity increased exponentially with the concentration. During thermal scanning of inulin concentrates (30–50%), two glass‐like transitions were detected (−74.98 to −72.28 °C;−24.25 to −23.45 °C), which were independent of the concentration. The obtained information will be useful for product development and structural characterization of inulin‐incorporated food products.Practical applicationsIncorporation of soluble fiber like inulin into food products has proven health effect. Knowledge of flow behavior and glass transition temperatures of inulin at selected concentrations will provide a better understanding of food formulation, transport, and storage. Dielectric properties of inulin solutions would help to employ microwave/radiofrequency heating of formulated foods. The information presented in the present work should be useful to the food and pharmaceutical industries for early prediction of food quality and process engineering.