Formulation and characterization of edible pea protein stabilized emulsions: the role of phycocyanin as a co-emulsifier

Food sustainability and functionality are of great importance and the increasingly burdened lifestyle makes them an issue urgent to be addressed. Herein, pea protein isolate (PPI) and phycocyanin (PC) from Spirulina platensis were used as emulsifiers of edible Oil-in-Water (O/W) emulsions. PPI particles formed by combining the pH-shifting method and high-pressure treatment, while PC was dissolved untreated in the occurred particles' solution. The obtained PPI particles- PC solutions were analyzed in terms of size with Dynamic Light Scattering (DLS), and for their Dynamic Interfacial Tension (DIT) with the pendant drop technique. Emulsions were produced using high-pressure and were analyzed in terms of size using Laser Diffraction (LD), and microscopically with Confocal Laser Scanning Microscopy (CLSM). The effect of Extra Virgin Olive Oil (EVOO) and Sunflower Oil (SFO) was examined for emulsions’ formulation and stability. It was found that PPI particles were at 200 nm with small PDI values, while the ζ-potential of proteins varied from negative for PC, positive for PPI and close to neutral for their combination. The droplet size of the emulsions varied from 4.4 μm to 111.6 μm, affected by the protein concentration, oil volume fraction as well as the oil type. To depict the oil phase, adsorbed proteins and particles on the CLSM were employed. Overall, the systems proposed are novel with high encapsulation potency due the high oil-volume fraction. They remain stable for over 20 days and are stained blue with PC, which can serve as a natural alternative to conventional chemical colorants used in foods. • Phycocyanin acts as stabilizer and coloring agent. • Phycocyanin and Pea Protein Isolate co-stabilized O/W emulsions. • Phycocyanin enhanced emulsions' antioxidant activity. • Emulsions with high oil content and strong stability were produced.