Microalgae-loaded SPI-based monodisperse emulsions prepared by PREMIX membrane emulsification: Effect of pH and HHP on droplet size and droplet size distribution

Emulsions containing Chlorella vulgaris (CV), Arthrospira platensis (AP), Soy Protein Isolate (SPI) powders, or their combination as emulsifiers were prepared at 2 or 3 % protein concentration by intramembrane PREMIX membrane emulsification. Then, the effect of pH (3.5, no-change, 10) and HHP (0.1 and 200 MPa) on mean droplet size (MDS) and size distribution (SPAN) of canola oil in water emulsions was assessed. Emulsions with individual emulsifiers showed undesired MDS and SPAN at pH 3.5, while plant-microalgae emulsions presented better MDS and SPAN values at all pHs. Emulsions at pH 10 had better MDS and SPAN values. AP emulsion prepared at 3 % concentrations showed the highest improvement in MDS and SPAN when 200 MPa were applied. HHP had a positive effect when applied to CV-SPI and AP-SPI at 2 % protein concentration. However, an adverse effect was observed at 3 % protein concentration. Microalgae and plant emulsions with interesting properties can be obtained by pH and HHP treatment.