Effect of voltage and air flow velocity of combined convective-electrohydrodynamic drying system on the physical properties of mushroom slices

• Increasing voltage or air flow velocity increased drying rate of mushroom slices.
• Increasing voltage or air flow velocity increased porosity and rehydration ratio of mushroom slices.
• Increasing voltage or air flow velocity decreased remaining moisture content of mushroom slices.

Electrohydrodynamic (EHD) drying is an innovative drying method. For this investigation, a combined convective-EHD drying system with two variables of voltage (at four levels of 0, 20, 25 and 30 kV) and velocity (at two levels of 0.4 and 2.2 m/s) on drying kinetics, remaining moisture content, porosity, shrinkage, rehydration ratio, shear strength, color, and microstructure of mushroom slices was envisaged. The eight drying treatments (30 kV–0.4 m/s, 25 kV–0.4 m/s, 20 kV–0.4 m/s, 0 kV–0.4 m/s, 30 kV–2.2 m/s, 25 kV–2.2 m/s, 20 kV–2.2 m/s and, 0 kV–2.2 m/s) were carried out at 45 °C for a period of 5 h. ANOVA showed that these eight drying treatments had a significant effect with p ≤ 0.01 on porosity and with p ≤ 0.001 on moisture content, shrinkage, rehydration ratio, and shear strength, but no significant difference was observed in the color of the dried mushroom slices. The advantages of the mushroom slices dried at a higher voltage or air flow velocity included a higher drying rate, porosity and rehydration ratio and a lower remaining moisture content. However, the higher voltage or air velocity caused the development of a wrinkled and broken structure, leading into more shrinkage and shear strength.