Non-contact dynamic detection of apple juice conductivity based on magnetic induction spectroscopy

Conventional methods for detecting juice conductivity encounter several challenges, including contamination, electrode polarization, and the inability to conduct online detection during flow. In this article, a non-contact dynamic detection method for apple juice conductivity based on magnetic induction spectroscopy (MIS) was investigated. A finite element model was established and validated to explore the effect of flow velocity, tube length and coil structure on the proposed method. The conductivity of apple juice was detected and corrected based on the results of finite element analysis (FEA). The results showed that the established finite element model was effective and reliable, and the root-mean-square error (RMSE) between the simulated and experimental values of the phase difference was less than 10%. The flow velocity of apple juice under laminar flow conditions had little effect on the detection of electrical conductivity. When the tube length exceeded 40 cm, the cell constant stabilized. A separation of 9 cm between the excitation and receiving coil facilitated the attainment of a larger cell constant. A decrease in coil radius resulted in an increase in the cell constant. The proposed method was verified through the detection of apple juice and the RMSE between the conductivity corrected values and the true was 0.093%. The findings may provide a reference for the development of conductivity detection device for juice based on MIS. •A finite element model was established to investigate how flow velocity, tube length, and coil structure affect MIS.•An infinite element domain was established in the finite element model to address far-field dissipation of electromagnetic energy.•The flow velocity of apple juice under laminar flow conditions had little effect on MIS.•The RMSE between the corrected conductivity values of apple juice and the true values is 0.093%.