A Comprehensive Review on Electrohydrodynamic Drying and High-Voltage Electric Field in the Context of Food and Bioprocessing

Increasing global energy demand and the application of more energy-consuming processes has forced food industries to investigate alternative processes. This article pertains to one such novel and promising alternative drying process called electrohydrodynamic (EHD) drying. EHD is a method of inducing electric wind that is generated by gaseous ions under the influence of a high-voltage electric field. This article evaluates the available literature and discusses the experimental investigations carried out to explain the effect of operating parameters on the drying rate and specific energy consumption (kJ/kg water) of the EHD process. Through the review it was established that the corona current increased linearly with an increase in applied voltage (kV) for both positive and negative polarities and a negative corona discharge produced a larger corona current compared to a positive corona discharge. It was also revealed that the specific energy consumption increased with an increase in applied voltage for both polarities but was lower compared to conventional drying processes such as fluidized bed drying; however, it was observed that the specific energy consumed by the EHD process was lower than that of latent heat of vaporization, indicating the removal of water from the surface of the sample by other means in addition to evaporation. Electrode configuration plays an important role in determining the efficiency of the EHD process; the multiple-needle electrode configurations had better efficiency than wire and single-electrode configurations. Recent and past studies on application of EHD both postharvest and in food processing were also reviewed and the benefit of using EHD for food and bioprocessing due to its unique properties supported the feasibility and applicability of EHD as a suitable alternative for processing thermally sensitive biological materials.