Non-contact Measurement of the Shrinkage and Calculation of Porosity During the Drying of Banana

A novel non-intrusive technique (stereo-correlation) was used to determine the apparent volume of a banana in convective drying condition. The volume was calculated using the 3D Digital Image Correlation method (3D-DIC), which provides the 3D shape of the banana during drying. The combination of this technique and mass measurement allows the calculation of the porosity using the model of Katekawa and Silva[ 1 Katekawa , M.E. ; Silva , M.A. 2004 . Study of porosity behavior in convective drying of bananas . In Proceedings of the 14th International Drying Symposium (IDS 2004) , Sao-Paulo , Brazil , August 22–25, 2004; B , 1427 – 1434 . [Google Scholar] ] and the graphical interpretation presented by Madiouli et al.[ 2 Madiouli , J. ; Lecomte , D. ; Nganya , T. ; Chavez , S. ; Sghaier , J. ; Sammouda , H. A method for determination of porosity change from shrinkage curves of deformable materials . Drying Technology 2007 , 25 ( 4 ), 621 – 628 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar] ] The banana shows an ideal shrinkage at the beginning of drying but stops shrinking at low moisture content, thus increasing the porosity up to 30–35%. The comparison of the experimental shrinkage and the calculated porosity with the experiments deduced from the literature enables us to conclude the effectiveness of the 3D-DIC technique as well as the porosity calculation model.