Modulating wettability of yeast protein particles by ball-milling to fabricate capillary oleogels with tunable...

One-step fabrication of protein-based oleogels via capillary forces has emerged as a highly efficient and scalable strategy, relying on micrometer-scale particles to create a robust structural network within the oil phase. Yeast protein (YP), an eco-friendly and nutritionally favorable sustainable resource, possesses an inherent particle size well aligned with this micrometer requirement. However, the native compact architecture of YP prevents its direct gelation. In this study, planetary ball milling was employed as a physical strategy to modulate the particle size and wettability of YP, facilitating the fabrication of YP-based capillary oleogels with water as the secondary fluid phase. The mechanical treatment of YP via ball milling for 30 min resulted in a substantial reduction in particle size and concurrently modulated its interfacial wettability from 76.21° to 83.92°, synergistically enhancing the structural homogeneity and mechanical strength of the oleogels. Ball-milled YP substantially enhanced the rheological properties of the resulting oleogels, with storage modulus enhanced by up to 110.75%, creep compliance reduced by up to 8.73-fold, and thixotropic recovery ratio increased to 70.48%. In addition, the dependence of oleogel performance on both the saturation of the secondary fluid and protein concentration (φ) was systematically investigated. Gel strength exhibited a non-monotonic dependence on the saturation of the secondary fluid, peaking at 0.16 with fully interconnected capillary bridges, while increasing φ monotonically enhanced structural homogeneity and strength through improved aqueous phase distribution and bridge coalescence. The findings demonstrated that the integration of mechanical milling and compositional refinement provides an effective methodology for engineering the microstructural and functional properties of YP-based capillary oleogels.