Particle size distribution and compositional effects on textural properties and appearance of dark chocolates

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° using a HunterLab Miniscan Colorimeter. Compositional parameters for particle size distribution were [D90 (>90% finer) of 18 μm, 25 μm, 35 μm and 50 μm], 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 (5737-1099 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°) 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

Characterization of melting properties in dark chocolates from varying particle size distribution and composition using differential scanning calorimetry

Melting properties in dark chocolates processed from varying particle size distribution (PSD), fat and lecithin content were studied using differential scanning calorimetry (DSC). Compositional parameters were PSD (D90 (90% finer than this size) of 18, 25, 35 and 50 μm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Variations in PSD had no influence on crystallinity of products. Fat and lecithin content influenced the degree of crystallinity and melting properties (Tend, Tindex and ΔHmelt) of the products. Increasing fat content caused consistent increases in degree of crystallinity and crystal size distribution, thus effecting significant changes in Tend, Tindex and ΔHmelt of their derived products. Increasing lecithin content however reduced the crystal sizes in products. Particle size (PS) increases had limited effects on Tonset, Tpeak, and ΔHmelt independent of fat and lecithin content. Significant decreases in Tend and Tindex were noted with PS increases at all fat and lecithin contents. Similar increases in Tend and Tindex were noted with increases in fat content at all PS and lecithin levels. Contrary, increasing lecithin content in products resulted in significant decreases in Tend, Tindex and ΔHmelt. Thus, variations in fat and lecithin contents during dark chocolate manufacture influence the crystallinity of products, and with PSD, they all influence the melting index (duration) of their derived products. 2008 Elsevier Ltd. All rights reserved