Effect of composition on the rheological properties of traditional balsamic vinegar

Aims: The influence of chemical composition (glucose, fructose, acetic acid, water, salts) on the rheological properties of traditional balsamic vinegars were studied as a function of their chemical composition at a range of temperature of 20-60°C. Preliminary studies were conducted on vinegar model systems (acqueous solutions) by performing steady shear and dynamic rheological tests in order to evaluatem the effect of chemical constituent alone and in combination on the rheological behavior. A fractional factorial experimental design was used to combine the composition variables (glucose content, glucose to fructose ratio, acetic acid, and potassium tartrate salt). By means of an multivariate analysis, a statistical model able to describe the effect of chemical composition on the rheological behavior of vinegar model systems was developed. Among measured rheological properties, dynamic viscosity was found strictly related to chemical composition. It is reasonable hypothesize that dynamic viscosity should be related to the sensory properties of traditional balsamic vinegars. Results suggest that dynamic viscosity should be used for a rapid and objective classification of traditional balsamic vinegars before the samples undergo to time-consuming and expensive sensorial analysis.