In a lot of the beverage distillation research papers I’ve been coming across, the idea of an odor threshold is mentioned. One particular paper from the gin paper round up, The Flavour Constituents of Gin (Journal of Chromatography, 1978) by D.W. Clutton mentions the concept and wonders why compounds below the odor threshold matter. One problem with Clutton’s inquiry is that there turns out to be a few possible thresholds.
I, for a while had been suspecting there was a threshold of perception and a threshold of attention. Because the nose is so sensitive, the mind can perceive astoundingly low concentrations of aroma compounds but we cannot exactly pay attention to them and name them. These ideas are really important to the distiller or blender because certain congeners like ethyl acetate and acetaldehyde want to be kept below but as close to the dividing line of perception and attention as possible. I suspect the reason is that these congeners have the ability to turn on our nutritional reward systems which changes the way we perceive the world (flavor mode which is kind of like beast mode!). The master Cognac distiller Robert Léauté referred to these two simple congeners as “aroma fixatives” without elaborating the concept.
Lots of people study sensory thresholds and the many types have more formal names than the ones I made up (stolen from wikipedia):
- Absolute threshold: the lowest level at which a stimulus can be detected.
- Recognition threshold: the level at which a stimulus can not only be detected but also recognised.
- Differential threshold: the level at which an increase in a detected stimulus can be perceived.
- Terminal threshold: the level beyond which a stimulus is no longer detected.
My threshold of perception is probably analogous to the absolute threshold. My threshold of attention is analogous to the recognition threshold.
In the past when I had explored the re-distillation of some commercial spirits (affordable bourbon) and examined the fractions, I had thought some of the spirits where improperly cut due to smelling lots of ethyl acetate and acetaldehyde in the first fractions. I was horribly wrong. The spirits were perfectly cut and perfectly blended but what I had experienced was those two particular congeners being bunched up and pushed over the recognition threshold line. If all the fractions were rejoined and re-cut to the original proof they would be back below the recognition threshold but still above the absolute threshold. They would be back to working their magic but you wouldn’t really know it.
A main objective of blending certain styles of spirits might be maneuvering ethyl acetate and acetaldehyde as close to the line as possible without going over. In the past this must have been quite the art (with lots of mishaps) but now it can be assisted with quick chemical analysis tools. In terms of this line I speak of, I think I have only ever experienced two improperly blended spirits on the market. One was a slivovitz and the other was a calvados. The distillers probably did not make mistakes while the blenders in the cellar probably did. I’m almost thinking I should buy some of these spirits, learn to fix them, and then put them on my cocktail list so I can prove my concept.
Certain styles of rum are known to be made in concentrates. I wonder if they are constructed in a way where ethyl acetate and acetaldehyde are above the recognition threshold (where they smell offensive) with the plan to blend them underneath later on. Sugar cane has different terroirs. Cane that is highest in favorable aroma precursors could be made to maximize aroma creation while deficient cane could be constructed closer to a neutral spirit so that it can blend down the concentrate. I’m definitely speculating. I’ve never seen any texts that describe the objectives of blending in terms of hitting chemical targets and I haven’t read much about creating concentrates.
So far the different thresholds have only concerned the aesthetic sensory side of the world but the symbolic side also has its various thresholds. I’ve never seen symbols articulated as having different thresholds but the idea is sort of hinted at in Roland Barthes’ Mythologies. Barthes somehow has the ability to explore the specific ways symbols, across a variety of topics, convey meaning to us but are below our threshold of recognition. We constantly take in these symbols but cannot recognize them with any ease.
I’m no expert of semiology (the study of symbols) but Barthes work resonated as I tried to learn a little about the sensory threshold issue. Barthes showed that there was so much to the world that impacted us that we were typically oblivious to. The same is probably true for spirits. for distillation mastery, we need to be aware of what is seemingly invisible and somehow learn to manipulate it.
To me, Barthes eventually stumbles and I suspect it is because he either does not drink enough distillates or because he drinks so much he takes them for granted. In an essay at the end of Mythologies Barthes tries to outline the mechanics of his mythologies. His framework is unfortunately unwieldy and cannot account for acquired tastes. Barthes system is not concerned with harmony and does not recognize how myths are constructed to have rhetorical power. Barthes system of signifier, signified, and sign can be simplified. Everything becomes a sign. Take Scotch whiskey for example. Barthes would see the flavor as the signifier and sophistication, nationalism, and masculinity as the signified. What Barthes does not realize is that the flavor could also be called the aesthetic sensory side with its own harmony and disharmony, while sophistication, nationalism, and masculinity can be called the symbolic side and also have their own harmony and disharmony. These harmonies are in fluctuation but what sets that in motion is the influence of the other side. The idea of sophistication can be so harmonious that it can bias and manipulate us into finding those challenging smokey aromas and high alcohol content harmonious as well. Slowly we will find the entire experience harmonious. Barthes system as it is cannot account for those interactions so he cannot explain the real significance of myth which is its rhetorical power to move and reshape us.
In one of his examples Barthes mentions a black soldier saluting the French flag. What is really significant to the myth that Barthes fails to mention is the handsomeness of the soldier. He has aesthetic features that convey capability and that demand our respect. A less fine specimen would not have the same rhetorical power. Harmony is particularly important to the equation. Accepting the French brand of colonialism follows the same journey as accepting Scotch Whiskey.
I first covered some of these idea a few years ago in Culinary Aestheticism– A Tale of Two Harmonies and it is amazing to see how much more I’ve learn about it since. These ideas which can be explored in spirits can be re-applied to just about every aspect of life as seen in Mythologies. Attempting to scale ideas to the acquired taste phenomenon will also give anyone a new perspective on Barthes.