Investigation of evolving cellular-level structure of apple during convective drying using X-ray micro-computed tomography

Structural alterations of plant-based food materials (PBFM) initiate at cellular-level. However, little is known about such alterations during drying at medium and high temperatures. Therefore, this research comprehensively investigated the evolutions of individual cells, intercellular spaces, and porosity of apples during drying. X-ray micro-computed tomography (X-ray µCT) has been performed on fresh and at different stages of convective drying (at 60 °C) of apple samples, followed by image processing and analysis. The study revealed the significant structural evolutions of apple cells, intercellular spaces, which contributed to macroscale deformation. The average equivalent diameter for apple cells before, during and after drying were 215±0.03, 119±0.004, and 95±0.01 µm respectively, whereas that of confined intercellular spaces were reported as 185±0.03, 188±0.04, and 181±0.02µm, respectively. Moreover, the porosity was increased during drying. In-depth understanding of the impact of drying kinetics on cellular-level structural evolution during food drying was also evident through the current study.