Dielectric properties of myofibrillar protein dispersions from Alaska Pollock (Theragra chalcogramma) as a function of concentration, temperature, and NaCl concentration

The open-ended coaxial probe technique was used to study the effects of frequency (500-2500 MHz), temperature (20-90 °C), concentrations of myofibrillar protein (0.5, 1.5, and 2.5 mg/mL) and NaCl (0.3, 0.45, and 0.6 M) on the dielectric properties of myofibrillar protein. Models describing the behavior of the dielectric constant (ε′), loss factor (ε″) were developed. ε′ decreased as frequency, temperature, and NaCl concentration increased, whereas ε″ decreased with increasing frequency but increased with increasing temperature and NaCl concentration. Minor differences in the effects of myofibrillar protein concentrations were observed; the trend of ε′ changes agreed with viscosity changes, namely the maximum value of ε′ and viscosity were achieved when the myofibrillar protein concentration was 1.5 mg/mL, followed by concentration of 0.5 and 2.5 mg/mL. The penetration depth was estimated under various conditions and decreased with frequency, temperature, and NaCl concentration increasing but increased with myofibrillar protein concentration increasing.