Effects of radio frequency heating on fruit and vegetable quality: mechanisms, physicochemical changes, and...

Fruits and vegetables exhibit heterogeneous moisture, complex microstructures, and thermal sensitivity, governing dielectric properties and RF heating behavior. Within the RF range (27.12-40.68 MHz), dielectric constant (ε') ranges from 60-100 and dielectric loss factor (ε″) from 100-500 at 20-25 °C, depending on composition and moisture. These properties determine energy absorption and penetration depth; heating is also modulated by structural heterogeneity and geometry. This review analyzes multiscale interactions among dielectric behavior, tissue structure, and RF energy deposition, distinguishing electromagnetic and thermal processes. At the cellular level, membrane permeability alteration and pectin degradation are governed by temperature-time history rather than RF-specific effects. At the tissue level, spatial variations in dielectric properties lead to non-uniform energy deposition, generating localized heating and temperature gradients that drive texture changes. At the quality level, enzymatic browning, pigment stability, and nutrient retention are controlled by thermal history, water mobility, and composition. RF processing influences quality through accelerated heating and reduced exposure time, rather than altering intrinsic reaction pathways. Despite advances, current models still lack fully validated multiphysics coupling among electromagnetic fields, heat and mass transfer, and quality kinetics. Future research should focus on integrated multiphysics modeling, dielectric characterization, and real-time adaptive control for predictive RF processing.