Scientists studying the behaviour of aniseed flavoured alcoholic beverages like the French alcohol Pastis, which turns cloudy when mixed with water, observed some surprising qualities of these unique emulsions.
The liquids - which have some important properties that could be interesting to the cosmetics and pharmaceutical industries - behaved in unexpected ways, according to the scientists.
"More knowledge of the parameters that determine the stability of these emulsions…might lead to better control of the emulsification process," concluded the study.
Spontaneous and sustainable emulsification The team, led by Elke Scholten of the Wageningen University, Netherlands, investigated the behaviour of aniseed flavored alcoholic beverages (PLBs), including French brands Pastis, Pernod and Ricard, as well as the similar Greek drink, Ouzo.
The alcohols spontaneously form emulsions when added to water without the need for either an emulsifier or any form of mechanical energy - two properties that are very interesting to the industry.
The method is currently used by the industry in the production of nanocapsules as it is possible to make much smaller particles than with conventional methods, according to the study.
The spontaneous emulsification process can be used for many practical situations such as the design of drug or active ingredients loaded particles, capsules or vesicles in a wide range of industries, explained the researchers.
PLBs have three components - alcohol, water and oil.
The oil component is mainly trans- anethol, which is soluble in alcohol but not in water.
When bottled the ratio between the three components means that the oil is still soluble in the mixture and therefore appears transparent.
However, as soon as the alcohol is added to water the oil comes out of solution and forms small droplets, causing the liquid to appear cloudy, explain the scientists.
Importantly PLB-based emulsions can stay stable for a number of months, and the team investigated the factors affecting the emulsions stability.
The observed behaviour of the emulsions differed markedly, and at times opposed, from the behaviour the scientists expected based on present theories regarding such three-component emulsions.
The team conclude that current theories do not seem to explain these results and that a better understanding of such three-component systems could be useful in the development of better commercial emulsions.