VOL. 21 NO. 5 (2009) AARTICLERTICLE A toast to dynamic NMR spectroscopy: towards a better comprehension of palatable emulsions David Carteau, Isabelle Pianet and Dario M. Bassani Institut des Sciences Moléculaires, CNRS UMR 5255, Université Bordeaux 1, 351 Cours de la Libération, 33405 Talence France. E-mail:
[email protected] Introduction and aniseed. One of the most intriguing cules that are in different environments.5 Memories of summer vacations on the properties of t-A, however, is its capabil- In many occurrences, however, the NMR Mediterranean would not be complete ity to undergo spontaneous emulsifica- spectra of emulsions are not very inform- without recollections of the refresh- tion upon rapid dilution of a concentrated ative due to inhomogeneous line-broad- ing anise-flavoured alcoholic beverages solution with a miscible but non-solubilis- ening of the signals. Surprisingly, this is served during the hot afternoons. Though ing solvent. This phenomenon, for which not the case for emulsions of t-A in water, varying in name and composition across the term “ouzo effect” has been coined though, as convincingly shown in Figure cultures (Raki in Turkey, Arak in Lebanon, by some authors,2 is responsible for the 1. The sharp and clearly distinguishable Ouzo in Greece, Sambuca in Italy and cloudy aspect of the above-mentioned signals are attributed to t-A located in Pastis in France), extracts from star anis beverages as the alcohol content of the different environments: a moderately (Illicium floridanum) are a common prin- hydro-alcoholic solution is dropped from polar aromatic environment within the cipal ingredient of the plant extracts used above 40% to ca 5% v/v and affects the aggregates, and a hydrophilic aqueous in their production.