Dielectric properties of Camellia oleifera seed kernels related to microwave and radio frequency drying

Understanding the dielectric properties plays an important role in the efficient use of microwave and radio frequency for dielectric heating and drying Camellia oleifera seed kernels. The dielectric properties of C. oleifera seed kernels were studied with the moisture content ranging from 5.50% to 44.22% (w.b.) over a frequency range from 10 to 3,000 MHz and a temperature range from 20 to 90 degrees C. The results showed that both dielectric constant and dielectric loss factor decreased with increasing frequency, but increased with increasing moisture content and temperature, and the increase rate was greater at higher temperature and moisture content than that at lower levels. The penetration depth decreased with increasing frequency, moisture content and temperature. And the maximum RF heating rates can be estimated by the dielectric property parameters. The present work may provide an effective guide to develop microwave and radio frequency drying protocols of C. oleifera seed kernels in the future. (C) All Rights Reserved