Effect of heating temperature on rheological properties of inulin gels (in English)
Polimery 2012, No 2, 111
In this work, 20 % aqueous suspensions of three commercial high performance inulin powders were prepared and subsequently heated, to study the effect of temperature on the rheological properties of obtained gels. Apparent viscosity, flow curves and frequency sweeps were measured. Moreover, the analysis of texture was carried out, where hardness (Fig. 1), adhesiveness (Fig. 2) and cohesiveness (Fig. 3) of the inulin gels were estimated. All the analysed samples had higher values of storage modulus (G') then loss modulus (G”) (Table 1, Fig. 4). Rotational rheometry showed that the examined gels revealed thixotropic (Fig. 6) and shear thinning behaviour (Fig. 5). Rheological properties of inulin gels were influenced by the structure properties of inulin powders and the preparation temperature. An increase in temperature caused a significant (p £ 0.05) drop in storage and loss moduli as well as a decrease in apparent viscosity values for the gels formed from inulin with amorphic structure. Inulin with crystalline structure was able to form stable gels only at high temperature.