Browsing by Author "Briones, Vilbett"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Effect of surface topography on color and gloss of chocolate samples
    (ELSEVIER SCI LTD, 2006) Briones, Vilbett; Aguilera, Jose M.; Brown, Christopher
    Different surface roughnesses of six chocolate samples were produced by molding over sandpaper of different graininess. Surfaces were examined for roughness (laser scanning microscopy), color and image texture (digital vision system) and gloss (glossmeter). Samples exhibited significantly different roughness among them expressed by the two parameters used to characterize their surfaces: the statistical average roughness, ARa (mu m), and the area-scale fractal complexity (dimensionless), Asfc. Surfaces of sandpaper and chocolate samples were highly correlated with these two parameters. Surface elements related to roughness were in the order of 3-14 mu m. Gloss of chocolate surfaces diminished exponentially as roughness increased while color (L*, lightness and whiteness index) decreased linearly. Parameters describing image texture, entropy and homogeneity, varied linearly with Asfc values. The structure of the surface of chocolate bars seems to play a decisive role in visual quality appearance. (c) 2005 Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    Item
    Microstructure affects the rate of chemical, physical and color changes during storage of dried apple discs
    (ELSEVIER SCI LTD, 2008) Acevedo, Nuria C.; Briones, Vilbett; Buera, Pilar; Aguilera, Jose M.
    Blanching, freezing and drying induce major changes in the physical properties of processed foods. Microstructural changes induced by these processes in apple discs were related to the degree and kinetics of browning and to fracture mechanics after drying and later storage at 70 degrees C under a wide range of relative humidity (RH). Blanched and unblanched apple discs were dehydrated by vacuum drying or freeze-drying to induce the formation of different structures, then equilibrated from 33% to 75% RH and stored at 70 degrees C in order to promote browning. Color changes on the surface of apple discs were analyzed non-invasively by image analysis using a computerized vision system. Pre-treatments and drying conditions modified the structural characteristics of apple discs, which in turn, changed sorption properties, texture hardness and browning development. Microstructural changes (e.g., loss of cellular integrity) promoted higher browning rates, the rate and degree of browning was analyzed. (c) 2007 Elsevier Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Scale-sensitive Fractal Analysis of the Surface Roughness of Bloomed Chocolate
    (WILEY, 2006) Briones, Vilbett; Brown, Christopher A.; Aguilera, Jose M.
    The surface roughness of stored chocolate bars was studied by scanning laser microscopy and area-scale fractal analysis. Topographic data were expressed by the statistical average roughness (Sa), by two parameters from area-scale analyses-the fractal complexity (Asfc) and the scale of the rough-to-smooth transition (SRC)-and by the relative area as a function of scale. The roughness measured with Asfc showed extremely low correlation with the SRC, indicating that these two, parameters can be considered to be independent. Asfc appeared to have some correlation (R-2 = 0.82) with the Sa, indicating that for these data Asfc and Sa are somewhat related. As surface roughness (Asfc) increased during storage, gloss decreased in a linear fashion (R-2 = 0.96), which is consistent with the proposal that surface roughness is intimately related to gloss. The scales of observation from about 0.5 to 100 mu m(2) were characteristic of the fat bloom interaction with chocolate surface and with the gloss. Fractal analysis provides parameters (Asfc and relative area) that are better than conventional arithmetic mean roughness for describing the surface changes during storage of chocolate. Both the complexity (Asfc) and the relative areas showed strong correlations with gloss (0.96 and 0.94, respectively), which is consistent with a facet-based scattering model.