Size-controlled and antioxidant proanthocyanidin nanoparticle-stabilized high internal phase Pickering emulsions for astaxanthin delivery

High internal phase Pickering emulsions (HIPPEs) provide a promising platform for astaxanthin (AXT) delivery. In this work, a novel HIPPEs was stabilized with size-controlled proanthocyanidin nanoparticles (PC-NPs) that synergistically enhance AXT bioavailability and antioxidant activity. The morphology, size and zeta potential of PC-NPs, alongside the microstructure, rheology, physical stability, and AXT encapsulation efficiency of the AXT- HIPPEs were characterized. Simulated gastrointestinal digestion showed that HIPPEs significantly enhanced lipid digestion and increased AXT bioaccessibility by 4-fold compared to free oil, while improving its retention to approximately 50% compared to 20% in oil after 28 days. In HepG2 cells, AXT-HIPPEs maintained cell viability above 80%, reduced triglyceride and total cholesterol accumulation, scavenged excess reactive oxygen species, and preserved mitochondrial membrane potential. These findings highlight HIPPEs as an effective platform to enhance AXT stability and bioavailability for functional foods and supplements.