Structure–process interaction in mass transfer processes: Application of ethanol and ultrasound in a vascular structure

This study aimed to evaluate the application of ultrasound and/or ethanol technologies prior to convective drying in samples with a particular vascular structure (pineapple core). Pineapple cores were cut in parallel (Lc) or perpendicularly (Tc) oriented to vascular bundles (VB). Effects on drying kinetics (50°C, ~1.0 m/s), shrinkage, rehydration kinetics (25°C), size recovery, and texture (50% uniaxial compression) were evaluated. Drying kinetics was fitted to Page model and rehydration kinetics to Peleg model. As main results, a reduction in drying time up to 60% was observed when the combined pretreatment for 10 min was applied in Tc samples. Regarding shrinkage, the Tc samples better preserved their diameter (>53%), while the Lc samples better preserved their height (>73%) after drying, which was explained by the parallel orientation of the VB to each dimension. In addition, Tc samples showed higher rehydration rate while the Lc samples showed greater water retention (~12 more). After rehydration, samples recovered their height and diameter by more than 70%. Furthermore, principal component analysis suggested that differences in shrinkage due to VB orientation are very related to rehydration kinetics characteristics. These results contribute to better explaining the technology–process–structure interaction. Practical Application: This work contributes to explain the interaction between structure, and ethanol-ultrasound pretreatment during drying and rehydration process. Consequently, providing knowledge about condition on which is better to use these approaches. For instance, depending on the pretreatment time, drying process can be hindered or improved. Furthermore, these results help to find better drying strategies for faster fruits waste drying, since pineapple core can be used as food ingredient and animal feed. Therefore, contributing to circular economy reusing food processing waste.