IDENTIFICATION OF FOOD PRODUCTS BY ELECTRICAL PARAMETERS

Abstract

The method of identification of food products based on the results of measuring electrical parameters is given. These parameters are used to select the reactive and active components of the admittance of the multi-element bipolar device, which supplies the controlled products. The paper presents an electrical model of a primary capacitive transducer of a two-electrode design with non-insulated electrodes and a controlled food product. It contains a parallel connection of the equivalent capacitance and resistance of the controlled object and in series the capacitance of the double layer of each of the electrodes. According to the electrical model, a mathematical model was obtained in the form of an analytical expression describing the active and reactive components of the admittance. Such models were analyzed in a wide frequency range for different values ​​of model parameters. The active and reactive components of the admittance depend proportionally on the reactive and active conductivities of the controlled object. At the same time, the change in the nature of the curves describing the active and reactive components also depends on the ratio between the active conductivity of the control object and the double-layer capacity and frequency. According to the mathematical model, the reactive component is determined by the sum of the components. One component is proportional to the capacity of the double layer, and the second is to the equivalent capacity of the object. As the frequency increases, the first decreases, and the second increases. Accordingly, a decrease in frequency leads to an increase in the first and a decrease in the second. From this it is obvious that in a wide frequency range the curve describing the reactive component has two extreme values. Also, based on the obtained simulation results, it is possible to estimate the influence of the double-layer capacitance on the change in the admittance components with constant other parameters of the mathematical model in a wide frequency range. On the basis of this, identifying signs were found, which should be used to identify food products. One of them is the frequency dependence of the active component. At the same time, at the beginning of the range, such a change is non-linear and depends on the frequency, and at higher frequencies it has an additive character depending on the frequency. Another identifying feature is a change in the shape of the curve, which reflects the reactive component of the admittance. A characteristic feature is the presence of two extreme values, which are maximum and minimum according to the frequency range. At the same time, the extreme value for a different value of the active conductivity of the object has its own frequency, and also changes in amplitude. Conclusions were made regarding the application of the identified identification features for the identification of food products by admittance parameters.