pH-shifted quinoa protein isolate-based nanocarriers for naringenin: Structure characterization and stability evaluation

Naringenin (Nar) is an important natural flavonoid compound with multiple health functions, but stability issues and poor solubility greatly limit its bioavailability. To enhance the water-solubility, chemical stability and bioavailability of Nar, quinoa protein isolate (QPI)-Nar and pH-shifted QPI (PQPI)-Nar nanoparticles were constructed in this study. The results of ultraviolet–visible and fluorescence spectra showed there existed the interactions between QPI or PQPI and Nar, with stronger interaction between PQPI and Nar. Thermodynamic analysis indicated the molecular interactions between QPI or PQPI and Nar were mainly driven by hydrogen bonds. Circular dichroism (CD) and surface hydrophobicity results revealed that the binding of Nar changed the secondary structures and reduced surface hydrophobicity of QPI and PQPI. The measured DLS, LC and EE results suggested that PQPI-Nar nanoparticles formed a more stable system with higher encapsulation capacity. Additionally, PQPI-Nar nanoparticles exhibited higher antioxidant activity, superior slow-release property and biocompatibility, as well as better thermal and ultraviolet stability than QPI-Nar nanoparticles. These results indicated that PQPI-Nar nanoparticles could effectively improve the bioavailability of Nar. This study may provide a theoretical basis for the promising application of PQPI-Nar nanoparticle delivery systems in the food industry.