Ovalbumin-gum Arabic Pickering W/O/W microcapsules for multivitamin co-delivery: fabrication, properties, and in vitro digestion

Co-delivery of hydrophilic and lipophilic vitamins offers synergistic nutritional benefits, but is often limited by solubility mismatch and the poor stability of conventional emulsions. In this study, complex coacervation, W/O/W Pickering emulsification, and spray drying were integrated to co-encapsulate vitamins B₁, B₂, C, D₃, and β-carotene, using protein-gum Arabic (GA) complex coacervates as particulate stabilizers. Ovalbumin-GA (OVA-GA) was used as the primary formulation, while whey protein isolate-GA (WPI-GA) served as a comparative system. At a protein-to-polysaccharide ratio of 3:2, OVA-GA microcapsules achieved encapsulation efficiency up to 91.3% for vitamin B₂ and in vitro bioaccessibility up to 72.4% for vitamin B₁ during simulated gastrointestinal digestion, corresponding to increases of 16.5% and 18.6%, respectively, relative to WPI-GA. Compared with WPI-GA, OVA-GA also showed higher emulsion viscosity and viscoelasticity together with smoother and denser particle morphology, suggesting a more effective interfacial particle layer and matrix barrier for vitamin retention and digestion-mediated release. The protein-dependent differences in encapsulation efficiency and vitamin-specific bioaccessibility may be related to differences in coacervate compactness and protein charge characteristics at pH 4.0. Taken together, these findings support the feasibility of this integrated strategy as a proof-of-concept platform for multivitamin co-delivery.