Effect of surface topography on color and gloss of chocolate samples

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.