Fabrication of soy protein isolate/fucoidan complex-stabilized high internal phase Pickering emulsions for enhanced naringenin stability, bioavailability, and 3D printability

Abstract

High internal phase Pickering emulsions (HIPPEs) have shown promising potential as advanced delivery systems for encapsulation and controlled release of bioactive compounds. In this study, soy protein isolate (SPI) and fucoidan (FUC) complexes were employed to stabilize HIPPEs, which were systematically characterized for their physicochemical, rheological, and microstructural properties. The results showed that the SPI/FUC-HIPPEs exhibited enhanced stability over 30 days, with the optimal FUC concentration (0.5%) and neutral pH conditions promoting the formation of a compact, multilayered interfacial film, resulting in a low creaming index (9.12%) that confirmed high stability. Rheological analysis revealed gel-like viscoelastic behavior with superior thixotropic recovery (exceeding 75%) and good thermal stability, underpinning structural resilience. When loaded with naringenin (NAR), these emulsions significantly improved the compound's stability, retaining 89.94% of NAR after 24 h of UV irradiation, compared to only 57.93% in MCT oil. Simulated gastrointestinal digestion demonstrated that SPI/FUC-HIPPEs preserved NAR integrity (83.37% stability) and enhanced its bioaccessibility to 73.20%. Cellular studies confirmed enhanced NAR absorption. The overall in vitro bioavailability reached 17.10%, representing a 3.6-fold increase compared with the control. This enhancement was associated with multiple energy-dependent endocytic pathways as well as paracellular transport. Furthermore, digested NAR-HIPPEs exhibited superior anti-inflammatory effects in macrophage models. Importantly, SPI/FUC-HIPPEs demonstrated excellent 3D printability, with SPI/FUC complexes conferring superior mechanical strength and shape fidelity. Overall, these findings establish SPI/FUC-HIPPEs as promising, multifunctional delivery systems for hydrophobic nutraceuticals, combining enhanced stability, bioavailability, and 3D printing performance.