High acyl gellan as an emulsion stabilizer

Area of Science:

• Food Science and Technology
• Colloid and Surface Chemistry

Background:

• Oil-in-water emulsions are widely used in food and pharmaceutical industries.
• Stabilizers are crucial for preventing phase separation and maintaining emulsion integrity.
• Gellan gum, a polysaccharide, can be modified to yield high acyl (HA) and low acyl (LA) variants with different properties.

Purpose of the Study:

• To investigate the efficacy of high acyl gellan gum as a stabilizer in sunflower oil-in-water emulsions.
• To determine the influence of gellan gum concentration and processing conditions on emulsion stability.
• To elucidate the mechanisms by which gellan gum stabilizes emulsions.

Main Methods:

• Preparation of oil-in-water emulsions with 30% sunflower oil using varying concentrations of high acyl (HA) gellan gum.
• Comparison of emulsion stability using low acyl (LA) gellan gum under similar conditions.
• Application of different processing techniques: high-pressure homogenization and ultrasonication.
• Characterization of emulsion properties, including phase separation, zeta potential, and rheological behavior of the continuous phase.

Main Results:

• Stable emulsions were achieved with HA gellan gum concentrations above 0.05% (w/w).
• LA gellan gum failed to stabilize emulsions under the tested conditions.
• High-pressure homogenization resulted in stable emulsions, whereas ultrasonication led to destabilization.
• Emulsions stabilized with HA gellan gum exhibited zeta potentials between -50 and -59 mV.
• The high viscosity and gel-like behavior of the HA gellan gum continuous phase contributed significantly to emulsion stabilization.

Conclusions:

• High acyl gellan gum is an effective stabilizer for oil-in-water emulsions at concentrations exceeding 0.05%.
• Emulsion stability is highly dependent on the processing method, with high-pressure homogenization being favorable.
• Electrostatic repulsion and the rheological properties of the continuous phase, influenced by HA gellan gum aggregates, are key factors in stabilization.