Influence of saturated triacylglycerols on cocoa butter crystallization and permeability characterized through complementary microstructural analyses

The crystallization of cocoa butter is governed by interdependent interactions between triacylglycerol (TAG) composition, polymorphism, and microstructural development. While the behavior of major Sat–O–Sat TAGs has been extensively studied, the contribution of minor trisaturated TAGs remains insufficiently characterized, particularly during the early stages of crystallization. In addition, solvent-based methodologies commonly used in previous studies may influence TAGs partitioning and complicate TAG-specific interpretations. In this study, the isothermal crystallization behavior of the trisaturated TAGs tristearin (StStSt) and palmitoyl distearoyl glycerol (PStSt), and their association with the crystallization behavior of the principal Sat–O–Sat TAGs (POP, POSt, and StOSt), were examined using a solvent-free, composition-resolved approach. Isothermal crystallization experiments were performed at 18.0–22.0 °C using differential scanning calorimetry (DSC), while TAG-specific changes in the liquid phase were monitored by HPLC. At temperatures ≤20 °C, thermal and compositional data indicated behavior consistent with α crystallization, whereas β′ formation was associated with POP, POSt, PStSt, and StStSt. At 22 °C, β′/β development was dominated by POP, POSt, PStSt, and StStSt, with limited participation of StOSt. Microstructural descriptors revealed reduced pore size, changes in fractal dimension, and decreased permeability, particularly at lower temperatures, indicating progressive network densification and increased tortuosity. Together, these results provide a consistent framework for interpreting the association between minor trisaturated TAGs, early crystallization behavior, microstructural evolution, and permeability in cocoa butter.