Jan Hartmann is co-founder of Aixsinthe, a young team of aspiring absinthe distillers. They’re about to release their third batch of their successful Absinthe Vivide! Being a Chemist, Mr. Hartmann has a unique perspective toward absinthes which he wants to share with the Absinthes.com readers today.
A Closer Look At Absinthe
Absinthes have a lot to offer not only for nose and palate, but also for the eyes. Whether it is the wonderful palette of colors of verte and rouge absinthes, the enchanting clouds and swirls forming in a glass of absinthe as it louches, or the sunset-like light scattering in a louched absinthe, preparing a glass can be a fascinating visual experience. But what should you look out for and what exactly are you looking at?
Most obviously, some absinthes can be very colorful. While there are colorless blanche absinthes, there are also many verte absinthes in all shades of green that, upon aging, will turn to a yellow, orange or brown color (feuille morte). A very limited number of pink or red rouge absinthes also exist.
Absinthes are colored by steeping more botanicals in the colorless product of the distillation step. The red color of rouge absinthes is usually based on hibiscus flowers. A great variety of herbs can be used to obtain a green color; most often, melissa, petite wormwood, hyssop and others are employed. Some cheap brands use spinach instead because it leads to a strong and robust green color that can be considered natural, but this is generally viewed unfavorably because it does not benefit the aroma or taste of the product. Absinthes colored artificially are even cheaper to produce and will not fade or turn yellow over time, but are vastly inferior in quality to naturally colored products. This is because usually in these cases the producers not only avoid costs in the coloration step, but also skip the distillation, using mixtures of essential oils added to neutral alcohol. Furthermore, using artificial dyes means missing out on the added complexity a coloration with herbs can provide. Finally, there is evidence that the chlorophyll in naturally colored absinthes positively affects the absinthes’ aging process while artificial dyes do not.
A cheap and easy way to test whether an absinthe is naturally colored is using a UV laser pointer. Naturally colored absinthes without feuille morte will show bright orange fluorescence due to their chlorophyll content. Once the chlorophyll has started degrading (even though the absinthe may still be green), the color of the fluorescence will shift to a yellowish white. Artificially colored absinthes show green fluorescence. More reliable, but also much more difficult tests can be performed using UV-Vis spectroscopy and thin layer chromatography.
The Louche Effect
Probably the visually most appealing aspect of an absinthe is its louche, i. e., the absinthe turning opaque when mixed with water, often creating beautiful clouds and swirls in the process.
This is due to essential oils in the absinthe, especially the anethole present in anise and fennel, which are soluble in alcohol but very poorly soluble in water. The addition of water to an absinthe thus causes the oils to separate and form a cloudy emulsion. Light scattering in the opaque liquid can lead to a marvelous play of colors ranging from celestial blue to fiery orange tones. As Oscar Wilde remarked:
A glass of absinthe is as poetical as anything in the world. What difference is there between a glass of absinthe and a sunset?
This comparison itself is not only poetic, it is also quite close to the truth! The colors seen when light passes through a louched absinthe are the same as those seen when light passes through the atmosphere at sunset because both are based on the same physical phenomenon, known as Mie scattering. In a sense, an absinthe truly is a sunset captured in a glass.