Bio-Engineered Plant-Based Emulgels for Chia Oil: Interfacial–Rheological Insights

The present study involved the engineering of chia-oil emulsions and emulsions using phycocyanin and sorghum flour as plant emulsifiers, and psyllium as a structuring agent. A central composite design was used to evaluate the protein ratio, the ultrasonication amplitude, and the total emulsifier concentration. The response-surface analysis identified an optimum at approximately 30S/70P and 45% amplitude, which in turn guided the development of the emulgel. The incorporation of psyllium resulted in the transformation of emulsions into shear-thinning emulgels. In emulsions, the consistency index exhibited an increase from 5.03 to 25.32 mPa·sⁿ as the flow index decreased from 0.31 to 0.01. A comparable trend was observed in dispersions. The results obtained from the small-amplitude oscillations confirmed the hypothesis that G′>G″ across all frequencies, and weak-gel formation was observed even at 0.5 wt.% psyllium. There was a significant improvement in physical stability, as evidenced by a substantial decrease in the Turbiscan Stability Index. FESEM revealed a fiber-like matrix embedding droplets at 1% psyllium, consistent with enhanced viscoelasticity and reduced mobility. The results indicate that secondary ultrasonic homogenization and the appropriate combination of emulsifiers and stabilizers are crucial to obtain emulsions and emulgels with optimal physicochemical properties. This suggests that these combinations may be beneficial for the development of more sustainable food products in the future.