In order to control the formation of fat crystal network structure and optimize the quality of the final product, this work aimed to investigate the effect of lard-based monoacylglycerol (L-MAG) on the isothermal crystallization kinetics, microstructure, thermal behavior, polymorphism and hardness of palm stearin (PS) at different temperatures of 4, 15 and 20 ℃. Our results showed that the types of fatty acids in L-MAG were identical to those in PS, but the contents of fatty acids were different between them. L-MAG could decrease the crystallization rate and extent of PS. However, this effect depended on the concentration of L-MAG and crystallization temperature. The effect of L-MAG on reducing the crystallization rate and the solid fat content value at equilibrium was more significant when the crystallization temperature was higher. Furthermore, this effect was proportional to the concentration of L-MAG in the range of 1% to 4%. Results of differential scanning calorimetry (DSC) and X-Ray diffraction (XRD) suggested that L-MAG could promote the crystallization of low-melting fractions and had little effect on the polymorphism of PS. Moreover, the hardness of PS increased after addition of PS, which could be attributed to the formation of a more compact and orderly crystal network with a high degree of space filling. The crystallization behavior of PS could be modified to improve the quality of the final product by controlling the concentration of L-MAG and crystallization temperature.

The stability of Pickering emulsion stabilized by solid lipid particles (SLPs) is directly impacted by changes in its crystal structure. The mechanism behind the effect of changes in the crystal structure of palm stearin (PS) as an ideal raw material for SLPs on Pickering emulsion stability is still unknown. In this study, PS-SLPs with different crystalline structures (size, crystal shape and morphology) (T40-PS-SLPs and SC-PS-SLPs) were prepared by adding 0.5%–5% of Tween 40 (T40) or sodium caseinate (SC), and oil-in-water (O/W) Pickering emulsion stabilized by SLPs was successfully constructed. Moreover, the relationship between the crystalline structure of the PS-SLPs and the stability of O/W Pickering emulsion stabilized by them was investigated. The findings indicated that most T40-PS-SLPs were lath-like particles with a particle size range of 124.1–370.1 nm, and the major crystal structure was type β’, while SC-PS-SLPs were type β’ irregular spherical particles with a particle size range of 309.7–346.2 nm. After sonication, both T40-PS-SLPs and SC-PS-SLPs wrapped 10% corn oil to form stable O/W Pickering emulsion; the average droplet size of the emulsion prepared with T40-PS-SLPs ranged from 0.76 to 2.23 μm and the lipid crystals in the emulsion were predominantly type β, while the emulsion prepared with SC-PS-SLPs showed average droplet sizes ranging from 0.81 to 1.27 μm and most lipid crystals were type β’. It was found that during the preparation of Pickering emulsion, the crystal form of T40-PS-SLPs changed from sub-stable type β’ to stable type β, while the crystal form of SC-PS-SLPs did not change significantly. After 60 days of storage, it was found that the Pickering emulsion prepared with T40-PS-SLPs containing more than 1% of T40 and that prepared with SC-PS-SLPs containing more than 1% of SC were stable for at least 30 days. Overall, the emulsion prepared with type-β’irregular lath-like T40-PS-SLPs with small particle size showed better storage stability. This study provides some data support for the development of O/W Pickering emulsion stabilized by lipid-based solid particles.