Mathematical correlations between selected quality attributes and electrical parameters of apple juice

Abstract

This study aimed at determining mathematical correlations between total soluble solids (TSS) content, content of organic acids (OA), pH value (pH), and density (D) of apple juice and their electrical conductance and capacitance using the RCC equivalent model of food products (resistance and capacitance). Linear correlations were determined between total soluble solids content, organic acids content, and density of aqueous solutions of the apple juice concentrate and values of their impedance (Z) and admittance (Y) in a frequency from 100 to 100,000 Hz; and their equivalent parallel capacitance (Cp) at frequencies of 100, 120, and 1,000 Hz; as well as their equivalent series capacitance (Cs) at frequency of 100,000 Hz. It was concluded that the correlations obtained from grounds for future studies on the development of a method for detecting adulterations (through watering) of apple juices based on measurements of electrical parameters, including the impedance or admittance. Practical applications Due to increasing requirements for the food quality and safety, as well as an increased demand for apple juice, many research works on the development of modern techniques for identification, detection of adulteration, and predicting its quality have been undertaken. Taking this into account, the research was undertaken to determine the mathematical relationships between selected quality attributes of apple juice (TSS, organic acids, pH, density) and their electrical parameters. The obtained significant mathematical correlations (r > 0.87 and p ≤ 0.01), indicate that the quality of apple juices can be predicted on the basis of simple impedance and admittance measurements at f = 100 Hz. These dependencies also justify the use of the RCC electric model for predicting the basic attributes of the apple juice quality, which in the future will make possible the development of a method for detecting its adulteration with water. On this basis, a relevant patent has been yet obtained.