Abstract

SANTACRUZ-VAZQUEZ, Verónica; SANTACRUZ-VAZQUEZ, Claudia; TOXQUI-LOPEZ, Santa  and  LAGUNA-CORTES, José Oscar. CHANGES IN SURFACE TEXTURE OF MELON (Cucumis melo cantalupensis) SPHERES DURING SPOUT FLUIDIZED BED DRYINGE. Vitae [online]. 2013, vol.20, n.3, pp.161-171. ISSN 0121-4004.

Background: Shrinkage and morphometric changes of fruit during drying are phenomena difficult to evaluate since foodstuff are not homogeneous material and their physical properties are strongly influenced by its moisture content. Objectives: The aim of this paper was to describe, by means of image analysis and fractal theory the morphometric changes in the surface of melon spheres during spout fluidized bed drying. Methods: Images of melon spheres during spout fluidized bed drying were obtained with a videocamcorder. The studied variables were the dry airflow, at levels of 2, 3, and 4 m/s; and dry air temperature at 70 and 80ºC. The shrinkage was defined as ratio of areas (A/Ao) of melon spheres, where Ao and A were initial and final dimensions of the spheres during drying, respectively. Six measurement zones were selected on the surface of the spheres to evaluate moisture content (MCZ). Surface morphometric changes of dehydrated spheres were evaluated by means of fractal dimension of the texture (FD_SDBC) of the obtained images during fluidized bed drying. Results: It was observed an irregular decreasing of spheres shrinkage (A/Ao) vs. drying time. The highest irregularity in the contraction of the sphere was obtained at drying conditions of 70ºC, and 2 m/s. At these conditions, a distribution of moisture content zones (MCZ) in the surface of melon spheres were observed. Distribution of MCZ generated the onset of zones with different moisture contents, along the drying on the surface of the spheres, which produced a non-homogeneous dehydration of the melon spheres. FD_SDBC values were between 2.22 and 2.30. It was observed that morphology changes of surface were progressive because of the dehydration. Conclusions: Morphometric changes on surface of melon spheres were influenced by a distribution of MCZ on the surface, found during spout fluidized bed drying. FD_SDBC values of the surface of melon spheres were increased, indicating a rougher surface during drying.

Keywords : Dehydration; Cucumis melo; morphology changes; deformation.

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