Phycocyanin-Psyllium Gel Systems: Rheological Insights and Functional Applications in Algae Oil Emulgels

Abstract This study examines the rheological and structural characteristics of dispersions prepared from phycocyanin extract and psyllium fiber, with a particular emphasis on their potential applications in algae oil-in-water emulgels. The experimental design analyzed the rheological characteristics of dispersions as a function of algae extract and fiber concentrations. The results showed that all dispersions exhibited shear-thinning behavior, with flow index values ranging from 0.09 to 0.33. The viscosity of the dispersions increased with psyllium concentration (consistency index varied from 0.38 to 130.38 Pa·sⁿ), while phycocyanin addition led to a viscosity decrease. Oscillatory tests confirmed the predominance of elastic behavior ( G ′ > G ″), with storage modulus values increasing from 0.02 Pa at the lowest psyllium concentration to 121.30 Pa at the highest. Microstructural analysis supported these findings, showing denser networks in psyllium-rich dispersions, while phycocyanin addition led to a more porous structure. In emulgels, droplet size analysis indicated that phycocyanin reduced the Sauter mean diameter from 0.480 to 0.262 µm, whereas psyllium increased it up to 3.448 µm. Stability tests confirmed that higher concentrations of both biopolymers improved emulgel stability, as reflected in lower Turbiscan Stability Index values. These findings suggest that psyllium-phycocyanin dispersions are promising for the development of stable, structured emulsions with potential applications in food and pharmaceutical products.