Texture is a key quality attribute in fat-based products. Understanding how formulation and processing influence structure formation in anhydrous milk fat (AMF) blended with vegetable fats is important in developing butter blends. This study examines the effects of 5% structuring fat: palm stearin (POST), palm kernel stearin (PKS), palm kernel olein (PKO), or shea stearin (SHEA) on crystallisation behaviour and texture, at slow or fast cooling. The structuring fats were blended with 75% AMF and 20% Rapeseed oil.
Blends were crystallized at slow (0.5 °C/min) or fast cooling rate (10 °C/min) and analysed for their crystallization and melting behaviour using differential scanning calorimetry texture (DSC). Upon crystallisation the samples were analysed for their microstructure using polarised light microscopy (PLM). Furthermore, the blends were analysed for mechanical properties (hardness & brittleness) and oil-binding capacity using a filter-paper-method.
Fast cooling of blends with PKS produced most hardness. high OBC, and a large high melting fraction (~73%). Moreover, PKO-blend obtained larger high melting fraction (~57% HMF) compared to the other blends, though lower than PKS. In contrast, blends with POST promoted earlier nucleation, and melting fraction like AMF (44% HMF), and softer, more uniform crystal networks with reduced brittleness. Slow-cooled blends showed less differences in terms of hardness, but DSC and PLM revealed distinct development e.g. with PKS and PKO showing merged low and high melting fraction. PLM images confirmed this with showing multiple sized crystals.
These findings highlight composition–structure–function relationships: lauric/myristic-rich TAGs (PKS-blend, PKO-blend) strengthen crystal networks through heterogeneous crystal populations; POP-rich POST-blend forms uniform but weak networks, while SOS-rich SHEA-blend produces AMF-like hardness but with greater brittleness. By combining DSC, PLM, and texture, this study links crystallization pathways (DSC), crystal morphology (PLM), and functional outcomes (hardness, brittleness, OBC), demonstrating how small additions of structuring fats modulate network strength and stability in AMF/RO blends.