Emulsions ensure stable liquids

Mixed liquids must not separate, become grainy, precipitate, or stiffen up. They must be homogenous, independent of their components.

Photo: LINX.

Einar Willumsen A/S are specialists in flavorings, extracts, and essential oils. Stable emulsion drops are essential for an unvarying liquid. With 120 years of experience in producing certified flavorings to the food industry Einar Willumsen A/S are well versed in the essentialities of unvarying liquids.

It is not clear for the naked eye if small changes happen in a mixture, but the Niels Bohr Institute have, with the help of small angle scattering, examined liquids down to the molecular level.

It is important for Einar Willumsen A/S to know whether their stabilizing agents have bonded to the surface of their droplets properly. If there are not any agents on the droplet surfaces, they will aggregate into continuously larger particles until oil and water agents separate as to independent liquids. If the stabilizing agents are bound properly to the droplet surfaces, the liquid will sustain its proper consistency.

We know this from a basic vinaigrette. It must be shaken occasionally, but a store-bought vinaigrette is most often homogenous and requires little to no shaking. Mixtures of liquids that do not normally mix, are called emulsions. In the store-bought vinaigrette an emulsifier has been added to ensure the stability of the mixture.

Since emulsion droplets cannot be seen with the naked eye nor can they be measured with ordinary tools, Einar Willumsen A/S and LINX industry portal decided to join hand in hand for this experiment.

LINX is an association that connects industry with universities. Here, LINX connected Einar Willumsen A/S with Professor Lise Arleth and here research team under the department of Neutron- & Xray scattering in the Niels Bohr Institute, that is part of University of Copenhagen.

The experiment showed that the tested stabilizers in Einar Willumsen’s emulsions, are stable.

This is of course good for the company’s products, but the experiment had to show why some emulsions are stable and others are not. Often one works in the blind. Sometimes one will add an ingredient to a soft drink which will immediately make it unstable and precipitate without any indication of why. Here, the aid of small angle scattering could help to unravel why and how structural changes in liquids occur. The goal of the work made at the University was as much a proof of concept as it was an investigative experiment.

“The knowledge found can help us improve the stability of our flavorings, extracts, and essential oils.” Says Jan Grøndal, who is CEO of Einar Willumsen, and adds:

“Next step could be to analyze the emulsions that become unstable to understand why some ingredients lead liquids to easier changes.”
In the experiment to types of emulsions were studied in which different stabilizing agents are used. The scientists could, with the help of mathematical models, measure both the amount and thickness of the stabilizer layer on the emulsion droplets. To study whether the emulsion was stable over time measurements were taken several times in the span of a month. The study showed that both stabilizing agents were well distributed through the liquid. Stable emulsions mean that taste and consistency are constant, which means longer shelf lives.

“One of the big goals with projects created by LINX is to help companies with method development, to better understand how to work with their products. Here, techniques that use xrays or neutrons have the advantage that they completely shine a light through the products, so that one can see more than just the superficial.” Says Jacob Becker-Christensen.

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Fact box

An emulsion is a mixture of two different liquids, that do not naturally mix. E.g. oil and water. If the mixture is shaken the two liquids will mix, but soon the oil will separate and lie on top of the water. We know this from chocolate milk. Where the chocolate will lie in the bottom until the bottle is shaken for the milk to be drinkable.

If one wishes one can add an emulsifier which strips the two liquids of their resistance towards one another and makes them mix.