Particle size distribution (PSD) and composition in dark chocolate were varied and their effects on textural properties of molten and tempered chocolates determined using a TA.HD Plus Texture Analyzer. Surface colour was evaluated in terms of CIELAB parameters L*, C* and h degrees using a HunterLab Miniscan Colorimeter. Compositional parameters for particle size distribution were [D-90 (> 90% finer) of 18 mu m, 25 mu m, 35 mu m and 50 mu m], fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Results showed that PSD, fat and lecithin content significantly (P <= 0.05) influenced the textural parameters with significant interactions among factors. Particle size was inversely correlated with firmness (1235-173 g), consistency (50,410-7029 g s), cohesiveness (1594-262 g), index of viscosity (57371099 g s) and hardness (7062-5546 g) with chocolates containing 25% fat and 0.3% lecithin. With higher fat and lecithin contents, PSD influence was reduced. PSD and fat concentration inversely influenced all colour measurements (L*, C* and h degrees) of samples. High correlations (r = 0.71-1.00, P < 0.001) were observed between texture parameters and colour. It was concluded that PSD, fat and lecithin contents and their interactions were central to changes in textural properties and appearance during processing of dark chocolates. (c) 2007 Elsevier Ltd. All rights reserved.