Development and Characterization of Pickering Emulsion Stabilized by Walnut Protein Isolate Nanoparticles

Area of Science:

• Food Science
• Materials Science
• Nanotechnology

Background:

• Walnut residue is a valuable byproduct with potential for high-value applications.
• Developing effective stabilizers for food-grade Pickering emulsions is crucial for the food industry.
• Nanoparticles derived from plant proteins offer a sustainable alternative to synthetic emulsifiers.

Purpose of the Study:

• To prepare and characterize walnut protein isolate nanoparticles (nano-WalPI).
• To investigate the impact of nano-WalPI concentration and oil volume fraction on Pickering emulsion stability.
• To enhance the utilization of walnut residue by creating stable food-grade emulsions.

Main Methods:

• Preparation of nano-WalPI using pH-cycling and ultrasound treatment.
• Formation and characterization of oil-in-water (O/W) Pickering emulsions.
• Optimization of nano-WalPI concentration (0.5–2.5%) and oil volume fraction (20–70%).
• Assessment of emulsion stability through creaming index, particle size, and rheological measurements.

Main Results:

• Nano-WalPI exhibited uniform size (108 nm) and excellent emulsification properties.
• Stable O/W Pickering emulsions were successfully formed using nano-WalPI.
• Optimal emulsion stability was achieved at 2.0% nano-WalPI and 60% oil volume fraction, forming a weak gel network.
• The optimized emulsion showed good thermal and storage stability, with a creaming index of 4.67% after 15 days.

Conclusions:

• Nano-WalPI is a promising stabilizer for creating stable, food-grade Pickering emulsions.
• The developed Pickering emulsion system demonstrates excellent stability and potential for food applications.
• This research offers a sustainable approach to valorize walnut residue into functional food ingredients.