Effect of electric field on calcium content of fresh-cut apples by inductive methodology

• An impregnation system based on the electric transformer concept was built.
• Electric fields induced by magnetic energy avoided the need of powered electrodes.
• The higher the voltage frequency the smaller the Ca2+ content became in apple samples.
• High overall operating costs resulted from the low power factor of this system.
• The electric transformer concept inspired a novel process system.

An experimental impregnation system based on the inductive methodology was established and used to investigate the effect of electric fields on the calcium content of fresh-cut apples. An induced electric field was generated when the Ca2+ solution acted as the secondary coil of the transformer system under the action of an alternating magnetic flux. The calcium content in fresh-cut apples was found to increase with the enhancement of the excitation voltage. Additionally, samples immersed in a CaCl2 solution exhibited a calcium content higher than those suspended in the calcium lactate solution. The latter presented a higher load power factor, the impedance in the CaCl2 solution being lower. Frequency at 20–60 kHz had a negative impact on the calcium content of fresh-cut apples due to the weakening of the electropermeabilization effect. This method utilized the conversion of electric energy into magnetic energy, and the electric field induced needing no insertion of powered electrodes into the solution under treatment. This might provide a reference for rapid impregnation of agricultural materials.