Energy, exergy, and drying kinetics of beetroot under electrohydrodynamic-assisted hot-air hybrid drying

Drying of agricultural products with minimum energy consumption and preserving their quality remains a major challenge in food processing. This study investigated beetroot drying in an electrohydrodynamic (EHD)-assisted hot-air method at 50–60°C and 15–30 kV by evaluating drying kinetics, effective moisture diffusivity, energy and exergy performance, thermal response, color, and ImageJ-based microstructural properties. Increasing temperature and voltage reduced drying period, and the Midilli et al. model provided the best fit under all conditions. Maximum exergy efficiency (0.0334) occurred at 15 kV–50°C treatment, while the highest surface temperature (41.02°C) was observed at 15 kV–60°C treatment. Effective moisture diffusivity increased from 5.87 × 10–8 to 1.11 × 10–7 m²/s with increasing temperature and voltage. The 15 kV–60°C treatment showed the lowest total color difference (ΔE = 2.445), whereas higher voltage levels increased color deterioration. ImageJ analysis revealed marked treatment-dependent variations in pore characteristics. Overall, increasing temperature and voltage enhanced moisture transport and shortened drying period under tested conditions; however, superiority over conventional hot-air drying cannot be established without a hot-air control. Optimization of drying temperature and applied voltage is therefore required to balance drying efficiency, color preservation, and microstructural integrity.