Particle-stabilizers modified from indica rice starches differing in amylose content

Area of Science:

• Food science and technology
• Colloid and surface chemistry
• Material science

Background:

• Pickering emulsions offer an alternative to conventional emulsions, utilizing solid particles for stabilization.
• Starch modification, such as with octenyl succinic anhydride (OSA), enhances its functional properties for food applications.
• Understanding the role of particle characteristics, like amylose content, is crucial for optimizing emulsion stability.

Purpose of the Study:

• To investigate the preparation and characterization of octenyl succinic anhydride (OSA) modified rice starches.
• To evaluate the emulsion stabilizing capability of OSA starch particles in oil-in-water Pickering emulsions.
• To elucidate the microstructure and stability mechanisms of these OSA starch-stabilized emulsions.

Main Methods:

• Preparation of OSA starches from rice cultivars with varying amylose content (1.90%–26.98%).
• Formation of oil-in-water Pickering emulsions using soybean oil and water (1:2, v/v).
• Analysis of emulsion droplet size, microstructure via optical microscopy, and stability over 100 days of storage.

Main Results:

• OSA starch particles successfully stabilized oil-in-water Pickering emulsions with droplet sizes ranging from 10–70 μm.
• Emulsions exhibited excellent stability over 100 days of storage, attributed to particle accumulation at the oil-water interface.
• A densely packed layer of starch particles at the interface provided steric stabilization, preventing flocculation and coalescence.
• Emulsification performance correlated positively with the degree of substitution of OSA starch (P<0.01).

Conclusions:

• OSA modified rice starches are effective stabilizers for oil-in-water Pickering emulsions.
• The steric mechanism provided by interfacial starch particle layers ensures long-term emulsion stability.
• Degree of substitution is a key factor influencing the emulsifying properties of OSA starches, more so than amylose content or pasting properties.