Oils are naturally immiscible with water. When such liquids are combined, they are referred to as an emulsion. Thus, an emulsion refers to a system of two immiscible liquids, one of which is aqueous. Emulsions represent milky-cloudy liquids. However, the consistency of individual emulsions can vary greatly from viscous to creamy. We reveal all the places where emulsions can be found in everyday life.
What characterizes emulsions?
A solution is called an emulsion when one liquid is in another. In this case, the two liquids are not able to mix with each other. One of the two liquids forms droplets. The droplets can be evenly distributed by shaking and stirring, and this condition can be obtained by adding emulsifiers. Two types are distinguished: the water-in-oil emulsion (W/O) and the oil-in-water emulsion (O/W). In the “water-in-oil emulsion,” the water is distributed in tiny droplets that are enclosed by the fatty component. Conversely, in “oil-in-water emulsion,” small fat droplets are enclosed by water.
Emulsifiers as mediators
To prevent the emulsion from separating back into its two components, so-called emulsifiers are needed. These are mediators between fat and water, because these substances have a fat-loving (lipophilic) and a water-loving (hydrophilic) component. In this way, the system can remain stable and flocculation can be prevented. Depending on the type and quantity of emulsifier used, different emulsions are produced which differ in consistency. Ideally, the emulsifier is soluble in the outer phase – the liquid surrounding the droplets. As a result, the emulsifier prevents the droplets from coalescing, thus stabilizing the emulsion.
Emulsions in food
Everyone is familiar with milk or cream as emulsions (O/W) from everyday life. Because these emulsions contain natural emulsifiers, such as milk protein or the phospholipid lecithin, the fat does not settle as easily as a layer. Lecithin is also found primarily in eggs, soy or rapeseed. Margarine, mayonnaise and dressings are examples of water-in-oil emulsions. In mayonnaise, egg yolk serves as an emulsifier and keeps it thick. In vinegar-in-oil dressings, mustard acts as a natural emulsifier to keep the two liquids from separating again. Another well-known emulsifier is the cholesterol found in butter or margarine.
Emulsions in cosmetic products
From cosmetics, for example, creams and lotions are known as emulsions. Glycerin, used in the creams, prevents them from drying out. Compressing agents make the consistency of cosmetic products smoother. Creams and lotions usually contain additional substances such as amino acids, antioxidants, preservatives, as well as perfume.
Quasi-emulsion – what is it?
Quasi emulsions are characterized by the use of fats and waxes. These separate the two liquid phases from each other. With this knowledge, you can make ointments yourself. One example is a cooling ointment made from yellow wax, peanut oil, water and a refatting thickener called cetyl palmitate. The wax and thickener are so viscous that they prevent the liquids from moving and thus the internal phase from merging.
Natural emulsifiers in the body
In addition to acting as an emulsifier, lecithin is involved in our metabolism. It transports fatty acids across our blood and through our body cells. Cholesterol is also a natural emulsifier. On the surface of our skin, it creates a protective layer from sweat. Cholesterol is also a component of many of the body’s hormones.
Synthetic emulsifiers
Edible fatty acids are synthetic emulsifiers. In the food industry, emulsifiers are labeled as E numbers. Emulsifiers are used in the production of the following foods, among others:
- In the production of butter and ice cream, emulsifiers lead to more air inclusions. This creates a better spreadability and smoothness.
- Mixed in bread, emulsifiers lead to a finer texture, greater volume and longer shelf life.
- Products made of chocolate emulsifiers give the right consistency and prevent white spots on the surface.
- In sausage, emulsifiers serve to keep the emulsion of protein, fat and water stable and create a pleasant consistency.
Detergents contain detergent surfactants – also called detergents. They act in a similar way as emulsifiers. During washing, the surfactants combine with oil and dirt particles and enclose them. The emulsified particles are simply rinsed out with the water.
Emulsions and our skin
Emulsions, as creams, ensure that our skin is moisturized and nourished. However, frequent applications of emulsions on the skin can make it dependent on the cream. Then the skin may stop producing its own oil or become dependent on the skin care substances. Therefore, use creams and lotions only if the skin’s own production of fat is not sufficient to meet external factors or if nutrients are lacking. You should also make sure to use high-fat W/O emulsions for dry skin. This will ensure an adequate supply of fat and moisture to the skin. On the other hand, if you have particularly oily skin, you should use light O/W emulsions. These do not “overgrease” your skin, but still provide it with nutrients and care substances.
Are emulsifiers harmful?
Artificial emulsifiers are no longer used just to make the consistency of food more pleasant, but mainly as food additives. These improve the color of the food, achieve a longer shelf life or change the taste. Many of the artificial emulsifiers – taken in small quantities – are generally harmless to our organism. However, there are emulsifiers that cause allergies, have a laxative effect or, when taken in larger quantities, hinder the absorption of essential trace elements.
