This study investigated the effect of isothermal hot air drying (ID), in which product temperature is controlled, compared with conventional hot air drying (CD) on the drying kinetics and quality attributes of pineapple slabs. Drying was conducted at 50, 60, and 70 °C with an air velocity of 1.0 m/s. The Midilli model adequately described the drying behavior under both methods. ID exhibited higher effective moisture diffusivity ( \({{\text{D}}_{{\text{eff}}}}\) ) and reduced total drying time by approximately 14–16% compared with CD across the investigated temperature range, indicating enhanced drying efficiency. Quality evaluation showed that ID significantly reduced dimensional shrinkage but resulted in greater total color difference (ΔE) relative to CD. Rehydration behavior was assessed through moisture uptake curves and rehydration rate analysis, and the Exponential model provided the best fit among the tested models. Higher drying temperatures decreased maximum rehydration rate for both methods, and ID samples exhibited slightly lower peak rehydration rates than CD. Overall, isothermal temperature control improved drying performance and reduced external shrinkage, although trade-offs in color change and rehydration characteristics were observed. These findings suggest that product-temperature-controlled drying may offer a practical approach for improving process efficiency in industrial fruit drying, while highlighting the need to balance drying rate and quality attributes.
