Molecular compound formation drives polymorphic transitions and functional enhancement in binary blends of palm olein...

This study elucidated the crystallization behavior, polymorphism, and functional attributes of binary blends of palm olein fraction (POF) and commercial OPO-rich fat (cOPO) across the complete compositional range (0%-100%, w/w). Compositional analysis revealed that POP-rich POF and OPO-rich cOPO exhibited molecular complementarity, providing the structural foundation for molecular compound (MC) formation. Multi-scale characterization, including DSC, isothermal crystallization, XRD, microscopy, and hardness analysis, demonstrated that blends containing 40%-60% POF exhibited non-linear increases in solid fat content and slip melting point, accompanied by β' → β polymorphic transitions, 2 L lamellar stacking, and the development of dense, interconnected disc-like crystals. These synergistic structural rearrangements markedly enhanced hardness and textural stability, confirming MC-driven crystallization as the underlying mechanism. The findings expand the understanding of fat structuring in non-ideal, industrially relevant systems and identify an optimal compositional window for formulating cocoa butter alternatives and structured lipids with desirable melting and textural properties.