Abstract: 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.

Key words: palm stearin; solid lipid particles; crystal structure; oil-in-water Pickering emulsion; storage stability