Dielectric Properties of Wine from 0.2 to 20 GHz

摘要

The usual characterisation of wines is based on chemical composition and sensoryconsiderations. We aim to describe the wine using mainly dielectric parameters, as well asexamining the data using statistical methods. Red wine samples were used for measuring dielectricconstant and loss factor at 0.2, 6 and 20 GHz together with the electrical conductivity.A vectorial network analyzer with a dielectric probe measures εr' and εr" from 200 MHz to 20 GHzwas used. The technique of measuring employed an open-ended coaxial probe.For each wine we determined the dielectric properties together with conductivity. Total measuredlosses can be broken down in dipolar and ionic (conductivity) losses, due to the conductivity,associated with salts in solution.The variation of the dielectric constant and the total loss factor with frequencies ranging from 0.2 to20 GHz turned out to be similar to those obtained by other authors for other foods. While thedielectric constant showed a monotonic and decreasing trend for increasing frequencies, the totalloss factor decreased to reach a minimum and then increased. In the area of the lowest frequenciesmeasured, we could observe an important contribution of the ionic conductivity to the value of thetotal losses.