Image analysis as a monitoring tool in the dehydration of banana slices

Abstract

The objective of this work was to evaluate the morphometric, fractal and color changes during the dehydration of banana slices through the use of image analysis. The convective drying was performed between 75 °C and 134 °C at an air velocity of 0.65 m s-1. Results showed that the images provided quantitative information of the morphometric changes (area and circularity reduction, and perimeter increase) due to the effect of thermal treatments. The analysis of fractal texture detected changes in the intensity of pixels, indicating that the surfaces were more complex and irregular as the moisture content of the product decreased. The fractal dimension of the contour (FDcont) increased over drying time. Regarding the color of the dried product, the parameters a∗ and b∗ increased, whereas the lightness (L∗) decreased, which is associated with the darkening of the slices and influenced by temperature increase. The micrographs determined the presence of pores that increased in quantity when temperature increased. Image analysis can be used as a monitoring tool due to its versatility, low cost, response speed, besides being a non- destructive technique.