Explosion puffing of bananas

Summary Banana slices were satisfactorily dehydrated by incorporating explosion puffing into the drying process. Water contents in the range 27–38%, steam temperatures of 152–160°C, internal pressures of 0.8–1.0 Kg cm ‐2 and residence times of approximately 1 min were typical explosion puffing conditions. Initial and final drying were performed with hot air at a temperature of 70°C, velocity 3.6 m s ‐1 , and relative humidity 35%. The increase in porosity obtained by puffing clearly reduced the total drying time compared with conventional air dried (CAD) samples. A simple diffusional model was applied to calculate the effective diffusivities of water vapour during drying of samples with and without puffing treatment. Analytical tests for colour differences, bulk density, porosity, rehydration parameters, and scanning electron microscopy in both puffed and CAD banana samples were also performed.