The properties of plant-based protein particles with co-spray drying agents

Spray drying, as an important way of protein drying, greatly promotes the industrial production of emulsion, but it will cause protein aggregation and functional reduction. In this work, we aimed to study the efficacy of protein particles produced by co-spray drying with a sugar (trehalose), a polysaccharide (maltodextrin) and a surfactant (polyglycerol fatty acid ester, PGE). Soybean protein isolate (SPI) and pea protein isolate (PPI) were used as model proteins. SPI, PPI and powders containing 10 % above additives in each protein were produced through spray drying. Pickering emulsions with 75 % oil phase were produced using the particles of protein (control) and particles of protein containing the above additives. Compared to that of pure protein, the particle size and surface hydrophobicity of rehydrate powders of protein containing additives were significantly lower. For the SPI group, SPI-maltodextrin, SPI-trehalose, and SPI-PGE had better emulsifying properties than that of SPI. For the PPI group, the PPI-maltodextrin and PPI-trehalose were better, while PPI-PGE had weaker emulsifying properties than that of PPI. The Pickering emulsion prepared by PPI-PGE stabilized emulsion was water-in-oil type while others were oil-in-water type. The emulsions stabilized by SPI-trehalose and PPI-trehalose particles had the smallest particle size (59.2 μm and 149.1 μm, respectively), the highest viscosity, produced the most stable emulsions. These findings show that sugar and polysaccharide based co-spray drying agents can improve the physicochemical and emulsifying properties of protein particles, of which trehalose appears to be highly effective. The outcomes of the work are expected to facilitate the properties of protein particles and the production application of Pickering emulsions in food industry.