Effect of Electrolytic Reduction on Dielectric Properties of Soybean Protein Solution

Food Technological Studies on Gelation of Soybean Protein Part V

Abstract

The effect of electrolytic reduction on the dielectric properties of the acid precipitated protein solution prepared from "old soybean" stored at 40°C (R.H. 75%) for 30 days was investigated. The electrolytic reduction current was set at 10mA (current density, 2.5mA/cmcm²). 1) The dielectric constant and dielectric increment of the solution had maximum values at 120 minutes after the start of electrolytic reduction. On further application, they decreased gradually. 2) The dielectric constant showed high frequency dependence and the anomalous dispersion was found in the frequency range from 1 to 10MHz/sec. 3) The dispersion of the dielectric loss had a wel-defined shape with a single peak between 1 and 3MHz/sec. With the application time of electrolytic reduction, the peak once shifted towared lower frequencies, and then higher ones. 4) In the frequency range from 10 to 100MHz/sec, the specific conductance appeared to depend on frequency and the frequency dependence increased with the application time of electrolytic reduction. 5) A plot of dielectric constant against dielectric loss at each frequency showed semi-circle in agreement with the equation of Cole and Cole. The dipolemoment μ, and mean dielectric relaxation time τ₀ and its distribution parameter α had maximum values at 120min-electrolytic reduction. On further application, they decreased gradually.