APPLICATION OF EXPONENTIAL RHEOLOGICAL EQUATIONS OF STATE TO DESCRIBE STRUCTURAL PROPERTIES OF HYDROCOLLOIDS

In the study paper, flow curves of potato and waxy starch pastes were interpreted. A rheological exponential equation of state for shear thinning systems was adjusted to the experimental data obtained at different temperatures. Distributions of rheological time constants were computed using a regularization method by Tikhonov. It was found that the values of those constants and their intensities depend on the composition of paste, whereas the position of global maximum of the distributions does not depend on the temperature. The characteristic times were determined using Equation (1) in the range (0.1 to 1 sec), and this fact indicates the predominance of viscous phenomena occurring while rheological features of pastes are in the process of moulding. Along with the raising temperature, the intensity increases of large time constants, which describe viscous contributions. The analysis of rheological properties of pastes indicates that a structure is developed in the paste, that "fluidifies" as the temperature increases. Starch pastes are systems capable of storing mechanical energy.