Colloids

Colloids are mixtures in which tiny particles of one material are suspended in another, often of a different phase. The particles run about 1 to 100 nanometres — larger than dissolved molecules but smaller than precipitate grains that filtration would catch. Aerosols, foams, emulsions, and gels are all colloids, and a solid suspended in a liquid earns the more precise name of sol. Foods are full of them: milk is an emulsion and a sol at once, while bread is a foam set solid. Colloid science underpins texture, stability, and appearance across the food industry.