Emulsification — the dispersion of one liquid phase in another through the reduction of interfacial surface tension — produces either oil-in-water (aioli, vinaigrette, cream) or water-in-oil (butter, margarine) emulsions. The distinction between permanent (stabilised with an emulsifier) and temporary (unstabilised, breaks within minutes) emulsions determines application and technique.
- **The emulsifier:** A molecule with both hydrophilic (water-attracting) and hydrophobic (fat-attracting) regions — it bridges the oil-water interface, reducing the surface tension that would otherwise cause phase separation. - Lecithin (egg yolk, soybeans): the primary culinary emulsifier. - Proteins: casein (milk), albumin (egg white), myosin (muscle protein) — all act as emulsifiers. - Mustard: mucilaginous polysaccharides provide emulsification in vinaigrettes. - **The droplet size:** Smaller oil droplets = more stable emulsion (more interfacial area = more emulsifier contact). High-power blending produces smaller droplets than hand whisking — more stable emulsions. - **Breaking an emulsion intentionally:** High heat (hollandaise); excessive addition of one phase (mayo); centrifugal force; extreme pH changes. For mayonnaise repair: start fresh with one egg yolk and add the broken mayonnaise drop by drop.
Modernist Cuisine