Ingredients for 100 g of cream:
- 65 ml distilled water
- 25 g petroleum jelly or coconut fat
- 5 g emulsifier (mono- and diglycerides of fatty acids, can be purchased online or from food additive suppliers as emulsifier E 471)
- 5 g glycerin (from the pharmacy or online)
List of required tools:
- 2 pots
- 3 bowls (slightly larger than the pot)
- Hand mixer with whisk
- Thermometer
Procedure:
- We need a water bath at approx. 70°C to heat the components.
This can be, for example, a bowl in a pot. - Heat the distilled water to 70°C.
- Heat the petroleum jelly or coconut fat to 70°C and dissolve the emulsifier in it. Then slowly add the mixture to the distilled water while stirring. This mixture needs to be stirred for a few minutes to achieve good mixing.
- Heat the glycerin in the water bath to 70°C and add it to the mixture.
- Let the mixture cool down while stirring constantly until the temperature drops below 40°C. The further the cream cools down with constant stirring, the more stable the emulsion will be.
What is the challenge in cream production?
As we have already learned, cream is a mixture of water, fat/oil, glycerin, emulsifiers, and possibly additives. More precisely, it is an emulsion, i.e., a stable mixture of substances in tiny droplets.
Emulsions are finely dispersed mixtures of two immiscible liquids that are mixed using auxiliary agents and energy input, thus not separating back into two distinct phases. If you put oil and water into a container, two phases are clearly visible. Think of a simple example of oil droplets floating on the surface of water. We often find emulsions in everyday life, e.g., shampoos, liquid soap, or skin creams.
Energy must be supplied to the reaction medium to mix the two immiscible phases. In the laboratory, this can be done using a magnetic stirrer or a suspended propeller stirrer.
If you let this freshly produced emulsion stand for a while, the water and oil will separate again. This is referred to as the emulsion not being stable. This raises the question: What can be done to create a stable emulsion so that water and oil do not separate from each other even after a year?
It is the surfactant properties of some substances, such as fatty acids or mono- and diglycerides, that are utilized to stabilize an emulsion. In everyday life, the more common term “emulsifier” is used for food or cosmetics, and “surfactants” are primarily found in cleaning agents, which are divided into “ionic” (“anionic” or “cationic”) and “non-ionic” surfactants.