Freeze-dried texturized
fruits were produced by freeze-dehydrating gels consisting of
fruit concentrate or puree. The products were dry and crunchy with a high content of
fruit ingredients. A dried texturized
fruit product is characterized by its porosity and pore-
size distribution, among other parameters. The objective of this work was to examine the possibility of assessing edible products by modifying a technique, which was first suggested by the Czech scientist Korcak,
65 years ago, for studies in the fields of geography and cartography. We were interested in whether this procedure would be suitable for describing the
distribution of pore
sizes within a dried texturized
fruit section or any other solid. We hypothe
sized that instead of dealing with pieces of land (islands or archipelagos, as suggested originally) suspended in water (seas and oceans), as is the case in cartography, it is possible to reverse the picture, and imagine the solid fragments as holes or pores within a solid matrix, and thus develop a new estimate of porosity. Another objective of this research was to test whether the calculated fractal index would be sensitive to food-processing conditions. We observed that for randomly selected, large enough pores within the freeze-dried texturized
fruit, the average fractal dimension of the circumscribing silhouette of the pores is about twice the measure of the
size distribution of a set of pores as estimated by Mandelbroth. The fractal dimension of the pore coastline is a property of the individual pores, whereas the fractal index deduced from the Korcak plot is a property of the group of pores. This
size-
distribution measure was also related to the porosity of the texturized
fruit. The proposed approach can be generally used to identify changes in the porosity of cellular solids, independent of their origin (i.e. edible or not), and as a simple tool for product development.