Sustainable stabilization of microfluidized chia oil nanoemulsions by mixed proteins

Bovine serum albumin (BSA) is an animal globular protein widely employed in emulsion-based formulations, such as food products. However, non-animal proteins have recently emerged as potential sustainable alternatives. Phycocyanin (PC), a protein derived from algae, is non-toxic and biocompatible. In this study, nanoemulsions containing chia oil were formulated using BSA, PC, and their 1:1 mixture as stabilizers. The Z-potential of protein solutions was determined at pH 2.5 and 4, surface tension and interfacial rheology were measured to assess interfacial properties, and emulsions were prepared using rotor-stator homogenization followed by microfluidization. The droplet size distribution, rheological behaviours, and physical stability (Turbiscan Stability Index) were evaluated, and pectin was incorporated at different concentrations to improve stability. Z-potential measurements indicated that pH 2.5 was optimal for protein stability. At this pH, PC and the protein mixture exhibited a more structured interface than BSA alone. Microfluidized emulsions stabilized with the mixture showed the smallest droplet size (150 nm) and moderate polydispersity (span = 2.48). The primary destabilization mechanism was creaming, which was mitigated by adding pectin; concentrations of 7.5-10 wt.% produced more structured systems, increased viscosity, and reduced instability. These findings highlight the potential of combining BSA and PC for developing stable and sustainable chia oil nanoemulsions.