Spirulina platensis protein isolate nanoparticle stabilized O/W Pickering emulsions: Interfacial adsorption and bulk aggregation

In this paper, novel food-grade Spirulina platensis protein (SPP) Pickering nanoparticles were obtained using a facile top-down approach of heat-set protein gel formation followed by controlled shearing and high-pressure homogenization. Results showed that nanoparticles not only adsorbed on the surface of oil droplets but also formed aggregation networks in continuous phases by varying nanoparticle concentration (c, 0.5-2 wt%) and oil phase fraction (φ, 30-65 wt%), which had a positive effect on the stability. Supported interfaces and regular polygonal shape deformations were observed in the micromorphology of emulsions when φ exceeded 50 wt%, becoming the more decisive factor of emulsion stability. And there was a significant positive correlation between φ and the recovery rate. Pickering emulsion with 30 wt% φ, stabilized by nanoparticle adsorption and aggregation network without the shared interface, had a recovery rate of 6.57-39.77% for the destroyed aggregation network after suffering 100% strain. While φ increased to 50 wt% or more, emulsions behaved recoverable at a rate of 56.69-73.86% for supported interfaces regardless of broken nanoparticle aggregation networks. Findings from this study on SPP nanoparticles and emulsions were of great significance for the utilization of sustainable microalgae protein in the food industry and would open avenues for rational designing of novel plant-based products in the future.