A colloid‑interaction model that predicts the net pairwise interaction energy between particles in an electrolyte as the sum of attractive van der Waals forces and repulsive electrostatic double‑layer forces; DLVO yields an interaction energy profile versus separation that helps predict aggregation, stability and potential energy barriers in dispersions and emulsions under conditions where other forces are negligible.

Principle

The balance between van der Waals attraction (short‑range, always attractive) and electrostatic double‑layer repulsion (longer‑range for charged surfaces in ionic solutions) determines whether an energy barrier prevents particles approaching close contact and thus whether aggregation is kinetically inhibited or favored; increasing ionic strength compresses the double layer and reduces repulsion, lowering the barrier to aggregation.

Demonstration

Situation: An oil‑in‑water emulsion is stabilized by charged droplets. Recognition: Addition of salt raises ionic strength. Action: Measure zeta potential and observe droplet behaviour. Consequence: Salt compresses the electrical double layer, decreases repulsive energy, the DLVO barrier lowers and flocculation or aggregation increases, eventually causing phase separation if other stabilising mechanisms are absent.

Misapplication

Applying DLVO predictions unchanged to systems where steric stabilisation, hydration forces, specific ion adsorption, surfactant layers or polymer-induced depletion dominate; the error is ignoring non‑DLVO interactions that can be equal to or larger than DLVO terms in many food colloids.

Consequence

DLVO provides a mechanistic baseline for formulation: it explains why ionic strength, surface charge and particle size affect stability and guides mitigation (e.g., charge control, ionic strength adjustment). Relying on DLVO alone for complex food systems can mispredict stability and lead to formulation failure.

Reversal

In systems with significant steric layers (polymers, proteins, adsorbed surfactants), hydration forces or specific chemical interactions, non‑DLVO forces dominate and the DLVO framework must be extended or replaced by models including those contributions.

Boundary

Clearly within: suspensions/emulsions of dielectric particles in aqueous electrolyte where surfaces are bare or only weakly coated and non‑DLVO forces are small. Boundary case: protein‑stabilised emulsions where adsorbed layers produce mixed electrostatic and steric effects. Clearly outside: polymer‑sterically stabilised colloids, strongly hydrated surfaces or systems with specific ion binding controlling interactions.

Semantic Tension

Parsimony and physical transparency of DLVO versus the complex, system‑specific non‑DLVO forces present in real food colloids; DLVO is a useful first approximation but suffices only when additional forces are quantified or shown negligible.

Synthesis

DLVO theory is the foundational mechanistic model for colloidal interactions in electrolyte solutions; in food formulation it should be used as the baseline to which steric, hydration and chemical specific forces are added explicitly when they materially affect stability.