Dielectric properties of litchi fruit (Litchi chinensis Sonn) at microwave frequencies

The dielectric properties of litchi fruit were determined using the open-ended coaxial probe method. The measurements were performed in the frequency range from 0.5 to 20 GHz during 3 days of storage at room temperature ( 24 degrees C). The dielectric properties increased with storage time. Additionally, measurements at different temperatures (24, 30, 40 and 50 degrees C) were determined. The dielectric constant (epsilon ') decreased with increasing temperature in a frequency range of 0.5-5 GHz; at higher frequencies, epsilon' increased with increasing temperature. The loss factor (epsilon '') value increased at frequencies higher than 2 GHz and decreased with increasing temperature. The results will be useful for further applications using microwaves, such as microwave-assisted drying, sensing of quality parameters, modeling, and heating to protect against molds or insects, among other applications.