Simple linear correlation between concentration and electrical properties of apple juice

The experimental material was the apple juice (8-12 °Brix) prepared from a concentrate (66.3 °Brix), n = 21. The TSS content was determined by the refractometric method. Measurements of the impedance (Z), resistance (R) admittance (Y) and conductance (G) were performed by means of the HP 4263B meter at a constant voltage of 200 mV, frequencies ranged from 100 Hz to 100 kHz and a temperature of approx. 20 °C. Linear correlations were derived using regression analysis to predict TSS as a function of electrical parameters (Y, G, Z and R). The relations observed were described with the regression equations in a standard form of: y = a ± bx. These equations are suitable for further studies to develop methods for rapid determination of the TSS content in different fruit juices as well as for the detection of their adulteration. For this purpose, the measurements of admittance or conductance over the range of 1-100 kHz may be applied.