Microstructure evolution affecting the rehydration of dried mushrooms during instant controlled pressure drop combined hot air drying (DIC-HA)

This paper presents a study on the microstructure evolution providing good rehydration performance of shiitake mushroom after instant controlled pressure drop combined with hot air drying (DIC-HA). The effect of variations of DIC process parameters on the cell membrane was studied via the electrical conductivity of rehydration liquid as well as transmission electron microscopy (TEM). Microstructural properties of dried products, including porosity and connectivity, were studied by scanning electron microscopy (SEM) and X-ray micro-computed tomography (mu CT). The results confirm that DIC pretreatment can facilitate a higher porosity of mushroom tissue, thus preventing collapse during subsequent hot air drying - provided that the product temperature remains below a critical temperature for retaining the integrity of the cell membrane. A new insight into the role of instant controlled pressure drop is to improve the microstructure of the samples. The porous structure implies potential innovative applications in the production of dry foods distinguished by good rehydration behavior.