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 lm), 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 lm 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.
- textural properties,
- mechanical properties,
- melting character,
- particle size distribution
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