Phase behavior and complex coacervation of concentrated pea protein isolate-beet pectin solution

Area of Science:

• Food Science and Technology
• Colloid and Interface Science
• Biopolymer Interactions

Background:

• Complex coacervates are crucial in food formulations, but their formation conditions, especially at high concentrations, require precise definition.
• Pea protein isolate (PPI) and sugar beet pectin (SBP) are widely used biopolymers with potential for synergistic interactions.

Purpose of the Study:

• To develop and validate a state diagram method for identifying critical pH boundaries in concentrated PPI-SBP coacervate systems.
• To investigate the influence of pH and polymer mixing ratios on coacervate formation and properties.

Main Methods:

• State diagram construction, zeta-potential measurements, rheological analysis, and phase composition determination.
• Isothermal titration calorimetry (ITC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) for thermodynamic and structural elucidation.

Main Results:

• The state diagram method successfully identified three characteristic pH transitions (pH_φ1, pH_opt, pH_φ2) in concentrated PPI-SBP solutions.
• The pH_φ1 showed a concentration-dependent shift, increasing with higher PPI-SBP ratios.
• Optimal pH (pH_opt) correlated with net charge neutrality and maximum storage modulus, indicating robust coacervate formation.

Conclusions:

• The state diagram offers an effective alternative for mapping coacervate formation boundaries in concentrated biopolymer systems.
• Understanding these pH-dependent transitions is vital for controlling coacervate properties in food applications.
• The study provides a framework for optimizing PPI-SBP coacervate formulations through precise pH and ratio control.