Effect of polysaccharides on conformational changes and functional properties of protein-polyphenol binary complexes:...

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• Soybean protein isolate (SPI) is a valuable food ingredient.
• Quercetin (Que) is a bioactive flavonoid with antioxidant properties.
• Polysaccharides can modify the properties of protein-carbohydrate complexes.

Purpose of the Study:

• To investigate how sodium alginate (SA) and dextran (DX) affect the binding and properties of SPI-Que complexes.
• To understand the interactions between SPI, Que, and different polysaccharides.
• To evaluate the impact on functional properties like emulsification, foaming, and antioxidant activity.

Main Methods:

• Multi-spectral techniques and Stern-Volmer equation to study binding.
• Analysis of amide bands (FTIR) for structural changes.
• Circular dichroism (CD) spectroscopy to assess secondary structure.
• Molecular docking and dynamic simulations to model interactions.

Main Results:

• Static fluorescence quenching confirmed Que and SPI binding.
• SA reduced SPI-Que binding affinity, while DX showed a promoting effect.
• Polysaccharide addition increased random coil structures in SPI.
• SA enhanced the stability and rigidity of SPI-Que complexes more than DX.
• SA-complexes showed improved emulsifying, foaming, and antioxidant properties.

Conclusions:

• Sodium alginate significantly alters the structure and stability of SPI-Que complexes.
• The interactions are driven by electrostatic forces (SPI-SA) and van der Waals forces (SPI-DX).
• SA addition leads to improved functional properties of SPI-Que complexes, suggesting potential applications in food formulations.