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.