Rheological characterisation of selected food hydrocolloids by traditional and simplified techniques

Empirical and fundamental rheological properties of six food hydrocolloids (carboxymethylcellulose, tara gum, guar gum, locust bean gum, xanthan gum and sodium alginate), as influenced by concentration, were evaluated and correlated. Furthermore, the possibility to estimate the empirical and fundamental parameters by using data coming from a very simple and inexpensive rotational viscometer prototype, was investigated. The prototype was build in laboratory and its simplicity consist of the capability to directly measure a voltage, correlated with the absorbed current, instead of a derived torque and rotation speed measurements of the cylinder probe. Fundamental rheological measurements were performed by using a controlled stress-strain rheometer, while a back extrusion test was performed in order to evaluate the empirical properties. The results reported that all the measured parameters are strongly correlated with the dispersion concentration. The simple prototype was able to predict the empirical parameters with R^2 value from 0.976 to 0.999 by means of exponential, linear, or power law functions and to assess the viscosity from power law or linear functions with R^2 close to 1 for shear rate higher than 50 s^-1.