Microstructural Changes of Apples (Granny Smith) During Drying: Visual Microstructural Changes and Possible Explanation from Capillary Pressure Data

The relationship between water content and capillary pressure and the microstructural changes in apples (Granny Smith) during drying was studied. Apples were dried in a pilot tray dryer and samples, with different moisture contents, were put in liquid nitrogen. The remaining water was eliminated by the critical point method to avoid structural changes and samples were then observed by scanning electron microscopy (SEM). It was possible to characterize the internal space of the apples during drying and find a relationship between the drying rate and microstructural changes. We postulate that shrinkage during drying is mainly due to changes in capillary pressure.