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Surface roughness during storage of chocolate: Fractal analysis and possible mechanisms
Author(s) -
Quevedo Roberto,
Brown Christopher,
Bouchon Pedro,
Aguilera José M.
Publication year - 2005
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-005-1093-2
Subject(s) - fractal dimension , surface roughness , fractal analysis , fractal , surface finish , materials science , chemistry , composite material , mathematics , mathematical analysis
Laser scanning microscopy and fractal analysis were used to determine roughness in the surface of chocolate samples stored under cycling temperature conditions (16 to 26°C) for 24 d. The four samples varied in the source of fat: 100% cocoa butter (CB), lauric and nonlauric fat replacers, and CB with 2% of nonlauric fat replacer. The response variable was the area‐scale fractal complexity (Asfc), equivalent to a fractal dimension. Asfc increased with time to an asymptotic value (AV) in much the same way as whiteness index, both being accepted proxies of surface bloom. Images produced from topographical data revealed clearly the increase in roughness. Chocolate samples prepared with CB replacers exhibited an induction period and a slower rate of change in surface roughness than chocolate containing only CB. A linear relationship between a normalized roughness and the square root of time was followed by CB chocolate samples for the period before reaching AV. This result suggests that either diffusion or capillary flow may be the mechanism involved in fat migration to the surface.