Effect of temperature and salt solution soakage on dielectric properties of black carp at 915MHz and 2450MHz

The dielectric properties of raw and preheated black carp flesh at different temperatures (10～90℃) , different frequencies (915 and 2450MHz) , and different concentration (1%, 2%, 3%and 4%) of salt solutions soakage were determined using the coaxial line method.Temperatures of the denaturation of myosin and actin in the raw samples were monitored by differential scanning calorimeter (DSC) .The influences of temperature, frequency, moisture content, concentration of salt solutions, and protein thermal denaturation on dielectric constant, dielectric loss factor, and penetration depth were analyzed.Results showed that salt solutions soakage had more great influence on dielectric constant than that on dielectric loss factor.With increasing temperature, the dielectric constant of the raw samples decreased more sharply than that of the preheated samples, and the dielectric loss factor of soaked raw samples increased more quickly than that of the preheated samples, which was due to moisture loss during heating caused by protein thermal denaturation.The dielectric loss factor of samples increased with increasing of the salt concentration of solution.Changes in the dielectric properties of the samples at 915 and 2450MHz with increasing temperature were found to follow second order polynomial equations.