Dielectric Properties of Beverages (Tamarind and Green) Relevant to Microwave-Assisted Pasteurization

Dielectric characterization of vegetable oils during a heating cycle

The knowledge of the dielectric properties of oils is of great importance for several industrial applications, such as microwave-assisted oil frying for foods and high voltage electric power transmission. In this paper, we present the complex permittivity of vegetable oils (canola, olive, soybean, coconut) at 2.50 GHz using the cavity perturbation technique from 28 to 200 °C (temperature close to the smoking point of oils). The measurements were taken with a cylindrical cavity operating at the TE₁₁₁ mode with an unloaded Q of 4950. In addition, free fatty acids, peroxide index and color were measured before and after heating.

Dielectric properties of fresh rabbit meat in the microwave range

Dielectric properties (DPs) of fresh rabbit meat in the microwave range (0.5 to 20 GHz) were determined. Three different muscles (Biceps femoris, Tensor fasciae latae, and Longissimus thoracis) from California rabbits (male and female) were measured with the open-ended coaxial probe method at temperatures of 20, 40, and 60 °C. To assess the possible effect of age, females of 100 and 180 days old were analyzed. DPs were affected by frequency, muscle type, age, gender, and temperature (p < 0.05). Dielectric constant decreased with increasing frequency. Loss factor decreased from 0.5 to 2.5 GHz due to ionic conduction, followed by an increase up to 20 GHz, dominated by dipolar relaxation. PRACTICAL APPLICATION: These results are key parameters for further quality sensing applications and for heating processes of meat rabbit using microwaves. Longer penetration depths were achieved at 915 MHz; this frequency is recommended for further applications. Besides, dielectric properties have potential to be a tool for identification of gender and age for slaughtered rabbits.