Browsing by Author "Quevedo, R"

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    Characterization of food surface roughness using the glistening points method
    (ELSEVIER SCI LTD, 2004) Quevedo, R; Aguilera, JM
    Several properties of foods, most notably visual perception and color, depend on the complexity of their outer surface. The so-called glistening point method based on specular reflection of an incident light beam is a simple, non-invasive optical technique used to quantify the roughness of a surface. Assuming that a surface has a macroscopic random Gaussian roughness distribution, the method determines two parameters: the correlation length (L) and the rms amplitude (sigma). Rougher surfaces have higher L and sigma values. Results show that the glistening point method is suitable for analysing food surfaces at the microscopic scale and is also useful to quantitatively follow changes in food surface roughness as during chocolate blooming or after removal of the outer wax layer in fruits. (C) 2003 Elsevier Ltd. All rights reserved.
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    Description of food surfaces and microstructural changes using fractal image texture analysis
    (ELSEVIER SCI LTD, 2002) Quevedo, R; Carlos, LG; Aguilera, JM; Cadoche, L
    Images, particularly photomicrographs, provide qualitative information about surfaces of foods and cells. Methods to analyze the texture of images such as fractional Brownian motion (FBMM), box counting (BCM), and fractal dimension (FD) estimation from frequency domain (FDM), were used to numerically describe the surfaces of foods and the microstructure of potato cells. A FD was calculated for each image using the power-law scaling for self-similar fractals. The surface of analyzed foods had FD varying from 2.22 for chocolate to 2.44 for pumpkin shell. As reference, the FD of sandpaper having increasing grain size or roughness varied from 2.37 to 2.65. FD was also useful to numerically describe microstructural changes with time of an isolated potato cell during heating in oil and of the surface of chocolate undergoing crystallization of fats (blooming). (C) 2002 Elsevier Science Ltd. All rights reserved.