Emulsions: Unity Between Polar Opposites
An emulsion is a mixture of two liquids that would otherwise be immiscible in one another (e.g. water and oil) by introducing them to one another with agitation and, potentially, emulsifiers. Emulsions come in two main forms 1) oil in water and 2) water in oil. The main difference between the two is the change in the continuous phase and the dispersed phase. In an oil in water emulsion, the water is the continuous phase while the oil is dispersed and vice versa for water in water in oil phase.
Figure 1: Concept of two-phase water-in-oil and oil-in-water emulsions.<https://www.researchgate.net/figure/Concept-of-two-phase-water-in-oil-and-oil-in-water-emulsions_fig2_260376328>
While emulsions can be used in a variety of ways, they are most commonly seen in food products that result in some household staples. Items such as milk, mayonnaise, salad dressings, margarine, and even ice cream can all be attributed to the process of emulsification. It is important to note that while you can suspend water in oil, or vice versa, for a short amount of time by agitation, the two will eventually separate into their respective layers. To prevent this from happening, the inclusion of emulsifiers (like lecithin) will help to surround the droplets of the dispersed phase and lengthen the amount of time the emulsion lasts. A good example of this would be the difference between an Italian dressing compared to mayonnaise. You do not have to shake the mayonnaise before using it thanks to the inclusion of eggs’ lecithin to act as an emulsifier. However popular these food products are, the emulsifiers within them can pose challenges for traditional analytical methods.
With emulsifiers’ affinity for liquids, they pose an issue with traditional analytical methods. To account for this, Eurofins offers a variety of tests to determine the product’s composition and inclusions. One such example would be our moisture method specific to lecithin. By utilizing Karl Fischer titration with the inclusion of chloroform to keep lecithin separate, we are able to accurately measure the water content in lecithin. Other approaches could encounter issues during titration or weigh-back.
Whether you are looking at the proximate composition, fat quality, color, or potential pesticides, Eurofins offers methods specific to emulsifiers for ensuring product quality and safety.
