Rheological characteristics, microstructures and stability of soy protein isolate nanoparticles stabilized silver carp oil pickering emulsions via mechanical-ultrasonic shearing

Reusing by-products from aquatic product processing stages, such as fish oil, remains a considerable challenge. In this study, soy protein isolate (SPI) nanoparticles stabilized silver carp oil Pickering emulsions were firstly manufactured via mechanical shearing, and then the effects of different ultrasonic energy densities (0, 0.27, 0.54, 1.08, 1.62, 2.16 kJ/mL) on the droplet size, rheological characteristics, microstructures and stability of final emulsions were compared. Results showed that ultrasonic treatments significantly reduced the droplet size of the emulsions and increased the emulsion stability and activity indexes. The ultrasonication (1.62 kJ/mL and 2.16 kJ/mL) successfully transformed the system from a low-viscosity fluid into a highly viscous system, with an up to 100-fold increase in apparent viscosity, which might be described to the intact interface layers and small droplet size of samples, as demonstrated by the optical microscope and confocal laser scanning microscopy (CLSM) images. These samples after ultrasonic treatments of 1.62 and 2.16 kJ/mL exhibited unique stability under storage, centrifugation, heating and oxidation conditions. In conclusion, SPI nanoparticles stabilized silver carp oil Pickering emulsions prepared using mechanical-ultrasonic shearing presents a green, efficient, and novel approach for the sustainable utilization of fish oil from aquatic by-products.