The chemical reaction of resilience: the Ouzo effect

The Ouzo effect (also called the milky effect or spontaneous emulsification) is the phenomenon of milky opacity that appears in certain aniseed drinks when mixed with water. It is so called because it is typical of aniseed liqueurs, as is ouzo itself. absinthe, anise oil, etc. All of them drinks with traces of the active principle that is anethole, this effect is usually called louche (from French: louche, cloudy) and appears as a microemulsion of this essential oil of Pimpinella anisum. The microemulsion can be generated even with small amounts of water and is characterized by being highly stable over time.

The Louche effect can be used to compare the aniseed content of these drinks, this is because the cloudier the liquid becomes at a given mixing ratio, the more aniseed the aguardiente contains. The addition of water blanches the clear liquid, the milky cloudiness is formed by an emulsion of oil in water which causes light scattering. The cause of the effect is the poor solubility in water of the essential oil anethole that the absinthe contains, therefore, it is not a chemical phenomenon but a physical one.

The effect can also be achieved (without adding water) by cooling the alcohol, this phenomenon is also known in nature as the Tyndall effect. Occurring mainly on sunny afternoons in late summer, sunlight is refracted by small particles in the air, giving the impression of a golden mist over the landscape.

The Ouzo effect has several applications in the industrial and cosmetic area, a large number of food products, personal hygiene products and detergents take the form of an emulsion to allow their stabilization for long periods of time. This technology has shown potential for the generation of surfactant-free microemulsions (compounds used in a wide variety of cleaning products for their ability to reduce the surface hardness of water) without the need to employ advanced encapsulation techniques, which are costly in large-scale production processes.

Let’s see the following video and if you can, then let’s go to work!