Effect of pulsed electric field pretreatment on mass transfer during hot air drying: Drying and rehydration properties of sweet potato

In this study, to investigate the effects of various pulsed electric field (PEF) strengths (0.5–2.5 kV/cm) on drying sweet potato, drying kinetics, mass transfer rate, rehydration kinetics, and microstructure of sweet potato during hot air drying were observed. After pretreatment of PEF, electric conductivity, and Z- index were increased as the strengths of PEF increased. The drying time was approximately 420 min for PEF at 1.5 kV/cm - 2.5 kV/cm and was almost 500 min for control group and the maximum values for moisture diffusivity and mass transfer was observed in 2.5 kV/cm. The shrinkage ratio and microstructure of sweet potatoes did not differ among groups; however, parenchyma cell membranes were empty and disrupted by PEF. The rehydration time decreased as the PEF strength increased, similar to the trend in drying times. PEF pretreatment resolves long-term hot air drying side effects such as quality deterioration and time requirements.