Dielectric Characteristics of Grape Juice and Wine

This study was carried out on samples of red grape juice and red wine at 20°C made from red varieties of grapes of the denomination of origin Navarre. The relative dielectric constant ε′r and the relative loss factor ε″r were measured in the frequency range from 200 MHz to 3 GHz with an open-ended coaxial probe technique. The dielectric parameters that best differentiate red grape juice from the red wine are the values of the dielectric constant at 200 MHz and 3 GHz. The presence of CO2 during alcoholic fermentation of the must may give unreliable measurements.