Microstructure and mechanical properties related to particle size distribution and composition in dark chocolate

Composition in dark chocolate was varied and the effects determined on microstructure, using light microscopy, and mechanical properties of molten and tempered chocolates, using a TA.HD Plus Texture Analyser. Compositional parameters were particle size distribution (PSD) (D90 of 18, 25, 35 and 50 μm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Micrographs revealed wide variations in sugar crystalline network structure and inter-particle interaction strengths related to PSD and fat level. Samples containing 25% fat had more crystal agglomerates, well flocculated with greater particle-to-particle interaction strengths than those with higher (30% and 35%) fat contents. Increasing the D90 to 35-50 μm caused broadening of the PSD, with particles becoming coarser, which were similar at all fat levels. Mechanical analysis showed that PSD, fat and lecithin content significantly influenced firmness of molten chocolate and hardness of solid (tempered) chocolate with significant interactions among factors. Particle size was inversely correlated with firmness (1235-173 g) and hardness (7062-5546 g). Greatest effect of PSD was with 25% fat and 0.3% lecithin. With higher fat and lecithin contents, the PSD influence was reduced. It was concluded that PSD, fat and lecithin contents and their interactions were central to mechanical properties of dark chocolates

Viability of probiotic strains Lactobacillus acidophilus NCFM (R) and Bifidobacterium lactis HN019 and their impact on sensory and theological properties of milk and dark chocolates during storage for 180 days

The popularity of chocolate as food around the world combined with high level of health-related awareness of the contemporary consumer, imposed the idea of enriching composition of different kinds of chocolate with probiotic bacterial strains. In this study, two strains of probiotic bacteria, Lactobacillus acidophilus NCFM (R) and Bifidobacterium lactis HN019, were incorporated in milk and dark chocolate. Final products were kept at two temperatures (4 degrees C and 20 degrees C) at which viability of added strains was monitored with the aim of determining the recommended storage temperature. In order to determine the effects of probiotics an examination of their sensory and rheological properties was carried out immediately after production (0-30 days) and during storage of 90 and 180 days. Based on the obtained results it can be seen that the probiotic strain L. acidophilus NCFM (R) exerted higher viability compared to strain B. lactis HN019 in both kinds of chocolates, while a greater number of cells of both strains was determined at 4 degrees C. The increase in yield stress of chocolates with probiotics with larger granulation was observed, while the apparent and plastic viscosity did not experience major changes. Despite the occasionally noticed sandiness, sensory properties of chocolates were not significantly changed during storage