Emulsion Stabilization Mechanisms of Natural Polysaccharides

Natural polysaccharides have attracted considerable attention as sustainable emulsifiers in food, pharmaceutical and cosmetic formulations. Their stabilizing action arises from a combination of interfacial adsorption, continuous-phase rheology modification and electrostatic or steric repulsion between dispersed droplets. At the oil–water interface, amphiphilic or proteinaceous regions of polysaccharide macromolecules align to reduce interfacial tension and form viscoelastic films. In the continuous aqueous phase, highly branched or charged chains increase viscosity and create network structures that hinder droplet coalescence and creaming. Surface-active fractions, often rich in arabinogalactan-protein moieties, deliver rapid adsorption and form protective layers via hydrogen bonding, hydrophobic interactions or complexation with co-emulsifiers. Electrostatic contributions derive from charged uronic acid residues, imparting zeta potentials that discourage aggregation under moderate ionic strengths. Steric stabilisation is dominated by the size and conformation of hydrated polysaccharide chains extending from each droplet, providing a physical barrier to close approach. The interplay of these mechanisms depends on polymer architecture, molecular weight, degree of branching and the presence of minor protein or phenolic components. Tailoring polysaccharide blends or exploiting complex coacervation with proteins can optimise interfacial coverage and network strength, yielding emulsions with fine droplet distributions, long-term physical stability and enhanced protection of encapsulated bioactives.

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Emulsion Stabilization Mechanisms of Natural Polysaccharides publication trend

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Technical terms

Emulsion: A biphasic mixture of two immiscible liquids (commonly oil and water) in which one phase is dispersed as droplets within the other.

Interfacial tension: The force per unit length existing at the interface between two immiscible liquids, reduced by adsorbed surface-active molecules.

Zeta potential: The electric potential at the slipping plane of a colloidal particle, reflecting surface charge and predicting electrostatic stability.

Complex coacervation: A phase-separation process in which oppositely charged biopolymers associate to form a dense polymer-rich phase (coacervate) around dispersed droplets.

References

1. Stabilizing the Oil-in-Water Emulsions Using the Mixtures of Dendrobium Officinale Polysaccharides and Gum Arabic or Propylene Glycol Alginate. Molecules (2020).
2. Flexibility and Hydration of Amphiphilic Hyperbranched Arabinogalactan-Protein from Plant Exudate: A Volumetric Perspective. Colloids and Interfaces (2018).
3. Encapsulation of salmon oil using complex coacervation: Probing the effect of gum acacia on interfacial tension, coacervation and oxidative stability. Food Hydrocolloids (2023).
4. A new hydrocolloid to rival gum Arabic: Characterisation of a traditional food gum from Australian Acacia cambagei.. Food Hydrocolloids (2024).