Oil-in-water emulsions with small droplet sizes can be formed without requiring either microfluidisation or heating to cause phase inversion, but rather by simple mixing of a pre-mixed composition of oil and a surfactant component comprising at least one surfactant component with aqueous material. The HLB value of the surfactant component can be selected to give a composition which, on mixing with a volume excess of aqueous material, spontaneously forms an oil in water emulsion with submicron oil droplets having a diameter <250 nm, suitable for filter sterilisation. Droplet diameters of <40 nm can also be achieved.
