Stabilization of High Internal Phase Emulsions by Sunflower Seed Protein Fibrils for Encapsulation of Lipophilic Nutraceuticals to Increase Their Bioaccessibility

Lipophilic nutraceuticals exhibit strong antioxidant and anti-inflammatory properties but suffer from poor water solubility and stability. Here, lipid-soluble nutraceuticals were encapsulated in high internal phase emulsions (HIPEs) stabilized by sunflower seed protein fibrils. Protein fibril formation was characterized, and HIPE morphology, droplet size, and rheological properties varied with fibril concentration and oil volume fraction. At a protein concentration of 10 mg/mL, the most compact HIPE microstructure was obtained at an oil volume fraction of 86%. Under these conditions, the oil droplet size decreased significantly with increasing fibril concentrations. Lipophilic nutraceuticals (0.01–0.3 wt %) were efficiently encapsulated and exhibited enhanced resistance to UV irradiation and high-temperature treatment. The retention of lutein, β-carotene, and curcumin exceeded 60% in HIPEs, compared to ∼40% in bulk oil. Furthermore, simulated gastrointestinal digestion studies revealed significantly improved bioaccessibility (>60%). These results demonstrate that sunflower seed protein fibril-stabilized HIPEs provide an effective strategy for improving the stability and bioaccessibility of lipophilic nutraceuticals.