Dielectric Properties of Vegetables and Fruits as a Function of Temperature, Ash, and Moisture Content

The dielectric properties of 15 vegetables and fruits were measured at 2450MHz from 5 to 130 °C. Equations were developed as a function of temperature, ash, and either moisture content or water activity, and compared to literature equations. Dielectric constant of vegetables and fruits decreased with temperature and ash content. However, ash was not a factor in the equations produced separately for fruits. Dielectric loss factor changed quadrically with increasing temperature: first decreasing and then increasing. This transition temperature decreased with ash content. Ash increased the dielectric loss factor. Garlic and potato gave unusual results, which could be explained by the behavior of solutions of inulin and potato starch, respectively.