Spirulina-Stabilized Emulsions as Sustainable Delivery Systems for β-Carotene-Rich Sunflower Oil Extracted from Dunaliella salina
The incorporation of lipophilic bioactive compounds into aqueous food matrices requires delivery systems capable of improving their dispersion and storage stability. This study developed oil-in-water emulsions containing β-carotene-rich sunflower oil extracted from Dunaliella salina, using a commercial blue Spirulina extract as a bio-based emulsifier. The Spirulina extract concentration was initially screened from 0.5 to 3 wt.%, and the processing conditions were subsequently optimized through a central composite design and response surface methodology. The systems were characterized in terms of droplet size distribution, physical stability, apparent encapsulation efficiency, microstructure, and β-carotene retention at 4 and 25 °C. A Spirulina concentration of 2.5 wt.% produced the smallest droplet size during the preliminary screening, whereas 3 wt.% resulted in larger droplets and broader distributions. The optimized formulation exhibited a D3,2 of 0.680 µm, an apparent encapsulation efficiency of 91.4 ± 2.1%, and a Turbiscan Stability Index of approximately 4.8 after 30 days. β-Carotene retention after 30 days was 68.5% at 25 °C and 91.3% at 4 °C, compared with 41.8% and 80.7%, respectively, in the non-emulsified oil. These results support the potential of Spirulina-stabilized emulsions as sustainable carriers for carotenoid-enriched food products.