Comparative Assessment of Ohmic, Induction, and Electric Coil Heating on Thermal Kinetics, Energy Efficiency, and Quality Attributes of Cow Milk

Electrical heating methods are increasingly recognized as efficient alternatives to conventional thermal processing, although their effectiveness depends on process control and product characteristics. This study compared ohmic heating (OH), induction heating (IH), and electric coil heating (ECH) for cow milk processing, evaluating heating behavior, energy consumption, physicochemical changes, and microbial quality. OH achieved the fastest heating, reaching 90°C in 17 min (4.70°C/min), followed by IH (22 min; 4.14°C/min) and ECH (57 min; 1.39°C/min). The superior performance of OH was attributed to volumetric heat generation driven by electrical conductivity, enabling rapid and uniform temperature rise. In contrast, ECH exhibited the highest energy consumption (0.57 kWh) compared to IH (0.24 kWh) and OH (0.19 kWh) due to surface-mediated heat transfer. OH minimized compositional changes in fat, protein, and lactose and better-preserved color (ΔE = 0.79), whereas ECH resulted in significant concentration-dependent changes (ΔE = 4.65). Microbial inactivation was most effective in OH-treated milk, as indicated by the lowest SPC and the highest methylene blue reduction time. FTIR analysis revealed minimal structural modifications in proteins and lipids under OH conditions compared to surface-based heating. Sensory evaluation further confirmed superior flavour, texture, and overall acceptability of OH-treated milk. These findings demonstrate that OH, particularly under optimized electrical conditions, offers a scalable and energy-efficient approach for dairy processing while enhancing retention of product quality.