Texture Analysis of Freeze Dried Banana Applying Scanning Electron Microscopy Combined with Image Analysis Techniques

Abstract

The aim of the present research was to evaluate the impact of freeze drying on texture properties of banana cv Cavendish. Freeze drying was performed at different rates (T1= 7h (-40°C)/24h (40°C); T2= 7h (-40°C)/48h (40°C); T3= 18h (-40°C)/24h (40°C) and T4 = 18h (40°C)/48h (40°C)). Microstructure was analyzed using a Scanning Electron Microscopy (SEM); Surface texture analysis by Grey Level Co Matrix Analysis (GLCM) and water absorbing capability and porosity by conventional techniques. Micrographs performed at 250 and 500 times magnification revealed that T1 and T2 showed higher porous size structure with larger and irregular cavities, and higher rehydration process was observed in T1 and T2 when it was related to T3 and T4. A higher rehydration process is due to a porous network with permeable barriers. Significant difference (P<0.05) were obtained for texture parameters, water absorbing capability and porosity. Hardness and roughness decreased in T3 and T4. These results suggest that prediction of texture parameters in banana cv. Cavendish can be performed easily by processing the surface and cross section images with SEM and GLCM methods