Methods to improve rice protein dispersal at moderate pH

Area of Science:

• Food Science
• Protein Chemistry
• Colloid Science

Background:

• Achieving stable rice protein (RP) dispersion at neutral pH is critical for its food industry applications.
• RP exhibits higher solubility at acidic (pH < 3) and alkaline (pH > 8) conditions compared to neutral pH.
• Sonication enhances RP solubility at pH 2, but precipitation occurs upon pH neutralization.

Purpose of the Study:

• To investigate methods for improving rice protein dispersion and stability at neutral pH.
• To explore the potential of using anionic polysaccharides to stabilize rice protein solutions.
• To evaluate the emulsifying properties of rice protein-pectin complexes.

Main Methods:

• Analysis of rice protein solubility across a range of pH values.
• Sonication treatment of rice protein solutions at pH 2.
• Complexation of rice protein with anionic pectin and sodium alginate at pH 2.
• Zeta-potential measurements to characterize complex formation.
• Preparation and evaluation of emulsions using rice protein-pectin complexes.

Main Results:

• Rice protein solubility increased significantly at pH < 3 and pH > 8.
• Sonication boosted RP solubility at pH 2 from 30% to 63%.
• Complexation with 1% anionic pectin at pH 2 shifted zeta-potential from +17.3 mV to -1.0 mV, preventing precipitation upon pH increase to 7.
• A stable emulsion was successfully prepared using the RP-pectin complex as an emulsifier.

Conclusions:

• Anionic pectin effectively forms a complex with rice protein at acidic pH, enabling stable dispersion at neutral pH.
• This complexation strategy overcomes the challenge of rice protein precipitation at neutral pH.
• The developed rice protein-pectin complex shows promise as a functional ingredient for creating stable food emulsions.