Advanced Aroma Theory Basics

[This post is an excerpt from a yet to be completed text on avant garde beverage distillation.]


Nature is a temple where living pillars

Let escape sometimes confused words;
Man traverses it through forests of symbols
That observe him with familiar glances.

Methods of evaluating and classifying aromas are invaluable to the distiller. Many distillers work in teams to sculpt aroma during the product development stage or to maintain consistency across batches once production has begun. Articulate communication is paramount to achieving either objective but unfortunately not many guides exist in the literature. Some scientists, notably Gordon Shephard the author of Neurogastronomy, have made great strides in understanding aroma perception but for the most part it is still beyond the reach of science and needs to first be teased out by the suspicions and empathy of artists. Many of the ideas here have been shaped & formed through countless conversations with the great brewers, bartenders , distillers, and wine makers of the world.

Identifying and quantifying aroma constituents in terms of molecules using advanced technology such as chromatography is a seductive idea, but it is impractical to all but the largest scale producers who typically only use the data to troubleshoot off-aromas and maintain consistency as production scales up rather than explore the patterns of pleasure. The literature on spirits analysis often states that efforts to reveal every chemical constituent of a beverage has produced little in the way of our understanding of aroma perception. The amazing power of the human nose leaves little incentive to apply high-tech analytic tools to the creative process. With practice and a framework of language as guidance, great empathy for evaluating aroma can be developed. Rendering a sensory experience in language, which essentially requires a transfer between frames of mind, may improve and refine the schemas we use for contrast detection when parsing aromas. This all means that talking about aroma will make your nose work better, faster.

Chemical analysis has limitations for categorizing aromas that are not well articulated in the literature. A fairly new idea that is only slowly gaining traction is that aroma perception is subject to significant amounts of illusion generated by its unique ties to memory. Chemical analysis, so far, makes no recognition of illusion or connection to co-experience and recollection.

Representing a sensation like an aroma with words can be a daunting challenge and many of the great distillers and spirit blenders of the world are not good at it. Many of these professionals feel (think non-linguistically) but cannot say, which unfortunately limits their ability to teach and solve certain types of problems.

One of the great problems with evaluating and categorizing aroma arises from our difficulty in separating the symbolic world from the sensory world. Though they often seem glued together, each has its own harmony and disharmony. Each also has the ability to influence the harmony of the other which is part of the mechanism by which we acquire acquired tastes. Prudish drinkers have been known to enjoy challenging sensory acquired tastes under the powerful symbolic influence of nationalism. Cultural rifts have also been narrowed by recognition of shared sensory values.

The aroma of Bourbon whiskey can be described as traditional, American, and grandfatherly which are all symbolic descriptors, but Bourbon can also be described as oaky, sweet, and round which all attempt responsibility for addressing Bourbon’s sensory side. The vocabulary of the highly subjective symbolic side is laden with rhetoric and therefore important to the marketer, while the vocabulary of the sensory side strives for objectivity and close representation of the sensory experience making it central to the concerns of the distiller. Beauty is the composite of both symbolic and sensory values, but to fully express it and put beauty to work, we need to understand the dividing line.

It could be argued that symbolic bias is shown in the word choices of the average person when trying to describe an aroma. More time is spent wielding rhetoric to sell aromas than objectively represent them. We are more comfortable labeling an aroma (or aroma set) as masculine or feminine than we are at describing the shape of the sensory tensions that exist within it. The ease by which symbolism is found in aromas somewhat obscures the raw sensory experience. Aromas mark and retrieve memories and therefore inspire us to be poetic in our word choices despite how subjective and personal the language. We forget our word choices are often based on inside jokes.

The idea of an aroma fault in a spirit is also symbolic. Aromas categorized as faults in spirits are only done so because besides typically being ordinary as opposed to extraordinary, they represent regrets, missed opportunities, and what could have been. Sometimes though, one imbibers’s fault is another’s feature especially if that latter drinker doesn’t know what could have been.

No word(s) can ever be an exact or universal stand-in for an experience, but some can be closer than others. It is useful to explore the origins of commonly used attempts at objectivity so we can expand upon them. When Bourbon is compared to oak, it is an actual object comparison. Object comparisons are very common but lack a lot of precision and assume familiarity with the compared experience. Unfortunately, few have ever had oak in singular form and the single word does not address all possible oak expressions (honey from oak trees is a great way to become familiar with the oak aroma).

Sometimes strings of object comparisons are used such as “oak, vanilla” or “raspberry, cherry”, but the comma is often the wrong logical operator to relate the descriptors. The experience may feel more like the unknown space between the two known values and a symbol that implies between-ness might be more appropriate. The comma as a logical operator has been known to throw many people off and can even make them question their ability to parse the experience. Strings of obscure object comparisons separated by commas can even be used as a means of cementing authority and professional critics are often accused of employing such tactics.

The supreme elaboration of the object comparison is the aroma wheel, which was developed to create standardized terms for wine tasting. The wheel begins in the center with generalized grouped comparisons such as “herbaceous / vegetative” and expands outwards into more specific sub-divisions like “dried” before ending at definitive comparison such as “hay” or “tea”. The aroma wheel is a useful teaching tool for tasters, and its creators share the opinion with the author that turning a sensory experience into language can help build the schemas we use to parse experiences and detect contrast, thus increasing enjoyment. The wheel unfortunately has the limitations of object comparison and is not tremendously useful in identifying patterns of attentional tension that can be beneficial to the creative process of building aromas.

The language we select to represent an aroma is constantly challenged by our attraction to grotesque (think of a mermaid) between-ness. The unknown tonal values between the aromas of raspberry and cherry are more prized than either known value alone. Between values are more attentional and draw us back to examining them, making them more memorable themselves as well as more likely to reinforce retention of paired experiences. They are a super normal stimulus. We crave the unique and extraordinary rather than the ordinary, obvious, or plebian. We put to use the extraordinary in aroma, such as a fine wine for a special dinner, as a tool that preserves the memories of the rest of the evening.

Like long echoes that intermingle from afar
In a dark and profound unity,
Vast like the night and like the light,
The perfumes, the colors and the sounds respond.

Beyond object comparisons, aromas can also be described in terms of the other senses. Cross-modal (a mode being one of the senses) comparisons, also called grounded metaphors, may seem unnecessarily more complicated than object comparison, but they do come to us naturally as proven by Lakoff & Johnson and when elaborated can take an understanding of aroma to the next level as one works with the sought after extraordinary and un-namable.

Describing the experience of one sense in terms of another may seem far-fetched, but when examining language applied to the other senses, the technique is very common. Vision is often described in terms of thermoception with warm and cool color analogies. Sound has been described in terms of color using the chromatic scale (*Piesse has a lovely chart). These analogies imply sensory linkages and evidence of them has been found in synesthetes.

Synesthesia is a condition where involuntarily stimulating one sensory modality produces an impression in another as well. However rare the condition, there is an astounding variety of types of synesthesia with reported cases of nearly every type of sensory linkage from seeing sounds (sensory-sensory) to smelling words (sensory-symbol). Synesthetes with sensory-symbol linkage may expose a neurological basis for our difficulties separating the symbolic and sensory worlds. Synesthesia implies that not everybody has the sensory linkage exhibited, but some researchers are starting to believe that olfactory-gustatory synesthesia is a learned type common to everybody. Aroma therefore can very effectively be described in terms of gustation and is seen by the author as the most useful method of categorizing aroma.

There are perfumes fresh like the skin of infants
Sweet like oboes, green like prairies,
—And others corrupted, rich and triumphant

When a Bourbon, which contains no significant sugar, is described as sweet, a cross-modal comparison has been made between olfaction and a gustatory division. Olfactory-sweetness is easy to identify and many people describe wines fermented to dryness, but having fruity aromas, as being “sweet”. We have evolutionary incentives to learn how to anticipate nutrition sources. The ability to predict food sources using our noses helps one to expend less energy while seeking out nourishment. Olfaction has evolved to anticipate gustation which in turn is a reliable determiner of nutritional value.

We can be seen somewhat arbitrarily as having twenty-one years of olfaction consistently anticipating gustation. When we start consuming alcohol at twenty-one, we enter a highly abstracted world where that sweet-smelling and sweet-tasting grape juice has now been converted to dry wine which often still smells the same. Fermentation and distillation are methods by which olfaction can be made to diverge from gustation. Divergence, as anyone who has consumed alcohol knows, can be highly attentional, memorable, and if done right, pleasurable.

The commonly accepted analogy of sweet smells can be expanded. Just like gustatory-sweetness, olfaction can converge with any of the other gustatory divisions. After olfactory-sweetness, the olfactory-umami may be the easiest division to identify (umami is sometimes also called the fatty-acid taste). The other gustatory divisions are not as easy to separate by empathy and it is hard to say whether the aroma of juniper is olfactory-acid or olfactory bitter. Indeterminate non-sweet divisions can usefully be called olfactory-dryness.

In distillates, the olfactory-umami can easily be found in muscat-based brandies like Pisco, agave-based spirits like Tequila, and Rums, especially those made from fresh sugarcane juice. The term “funky” has often been applied to an umami quality in spirits as well as the older term “hogo” which was often used in descriptions of early rums. The olfactory-umami, like everything else, has a spectrum with the darker or heavier end often being described by the Spanish word “rancio” and commonly applied to red wines and sherry.

Umami is not a widely recognized gustatory division, but understanding the olfactory-umami may help explain the gustatory phenomenon. Fatty acids, besides being found in meat, are also found in non-animal sources such as grapes, sugar cane, and agave. The heat of atmospheric distillation provides an opportunity for esterification where fatty acids react with alcohols to produce distinct volatile aroma compounds. Fermentation produces similar aroma compounds as does other processes like Maillard reactions (which also happen during beverage distillation) and reactions related to enzyme activity. The organic chemistry unfortunately can get intricate very quickly and so can the neuroscience but basically we smell the aroma compounds and because prior experiences has already linked the volatile fatty acids and their even more volatile esters, olfaction alone produces the illusion of tasting the umami. This idea of smelling the umami is not widely recognized or even widely studied, but the idea that we evolve to expend as little energy as possible when searching for nutrition makes it probable. Sensory linkages can make us better adapted for survival.

The gustatory patterns of pleasure are widely known. We enjoy attentional tension such as the bitter-sweet, salty-sweet, umami-sweet and “sour” (acid-sweet). The same patterns exist once olfaction is categorized in terms of gustation. Olfactory-sweetness contrasted with olfactory-dryness forms the basis of most culinary aroma creative linkage patterns.

When Bourbon is described as round, olfaction is being compared to the haptic sense which is our sense of touch. Haptic aroma analogies go back at least as far as the ancient Greeks. According to the Greek philosopher Democritus, “Sweet” things are “round and large in their atoms,” while “the astringently sour is that which is large in its atoms but rough, angular and not spherical.” Saltiness is caused by “isosceles atoms” while bitterness is “spherical, smooth, scalene and small.” Bourbon is often described as round relative to the more angular rye whiskey. Empathy tells us Green Chartreuse is nearly all angles and therefore its aromas may be from the spectrum of olfactory-acid.

Neuroscientist Richard E. Cytowic’s book on synesthesia, “The Man Who Tasted Shapes”, describes a synesthete with permanent haptic linkages to his flavor perception. He experiences food similar to Democritus’ analogy, but on non-voluntary terms. Quinine to Cytowic’s subject, “felt like polished wood because it was so smooth.” Angostura Bitters was “an organic sphere”, “with tendrils”, “the shape feels like a living thing, see, which is why I say ‘organic’. It’s round but irregular, like a ball of dough.”

We see the terms “flinty minerality” or “wet cobble stone” used all the time as descriptors for wine aroma and take for granted their origins. Many wine analogies may be cross-modal haptic references similar to Democritus early explanation of flavor or Cytowic’s synesthete. Stone has a texture and we find that texture an analogy for the aromas found within the wine. We know the sensation of “minerality” is the product of volatile aroma rather than non-volatile dissolved minerals because the “minerality” in question carries over into distillates.

The word “acrid” may be also rooted in a comparison to the haptic sense. Acrid is often used to describe the sharpest most angular aromas such as acetic acid, ammonia, or bleach. The word saw more common usage in the 18th and 19th centuries and was used to describe sharp but less extreme aromas like ginger, galangal, and cumin. The sensation of the word said aloud has a striking correspondence to the shape of aromas described as “acrid”. The phonetics of our word choices is not always arbitrary and even infants have been found to match nonsense sounds to shapes consistently with adults. Aromas referred to as acrid with the current usage of the word are most often always flaws and end up in the distillates of stressed and often oxidized fermentations.

The aroma of some distillates like those in the palm sugar based rum, Batavia Arrack, defy most attempts at object comparison. Their extraordinary foreignness cannot even clearly anticipate a gustatory sensation, but somehow a shape often comes to mind and the aroma feels like an elegant expression of what could be called “acrid”.

One of the most complete cross-modal systems of categorizing aroma comes from the mid 19th century French perfumer G. W. Septimus Piesse. Piesse compared olfaction to the auditory sense and in his seminal book The Art of Perfumery, he constructed elaborate charts that compare common perfume aromas to musical scales. The resultant order of the charts is startlingly intuitive and Piesse found that constructing aroma sets guided by the rules of common acoustic harmony also resulted in olfactory harmony. The acoustic metaphor “bass note” still lingers in common usage to describe aromas like vanilla or heliotrope and more than likely has its origins in Piesse’s odophone. Literary symbolists, surrealists, and futurists were later influenced by the analogies of the odophone and applications of the idea can be seen in the mouth-organ played by the main character Jean Des Esseintes of Joris-Karl Huysmans’ novel Against Nature or similarly of the scent-organ featured in the dystopian future of Aldous Huxley’s Brave New World.

The mind is known to create enduring sensory after-images in every sensory modality, but notably olfaction which perfumers often refer to as sillage (an after-image is a sensation that endures after the stimulus has been removed). Piesse was so bold and thorough in exploring his ideas as to hypothesize that with these after images, the mind could neutralize “pestilential” or “ammoniacal” aromas with “acidic” aromas. The result would seem like the real chemical reaction of ammonia and acetic acid where their acrid aromas disappear but be constructed solely by the mind. Aromas such as that of juniper, cedar, the herbs of Provence, etc. are known to have antiseptic, purifying and hygienic olfactory symbolism, but also they seem to converge with the olfactory-acid. Each of these purifying aromas are also deeply rooted in aromatizing meat and fish which as they mature and spoil produce “pestilential” aromas. The interaction of sensory after images in the mind may also be the basis for reactive wine and food pairings. [Later with the help of Neurogastronomy I learned about contrast enhancement in space and time for wine and food interaction.] More than one hundred and fifty years after Piesse’s ideas were first published, little is still known about the subject.

The language of color is also useful in categorizing aromas. Green and Yellow as prefixes for the Chartreuses are chosen to converge with the respective spectrums of aromas contained within. Wines have been known to have their colors abstracted naturally and unnaturally to better converge with their aromas. Barrel-aged spirits are often colored with caramel to have closer tonal sympathies with their aromas because the barrel, if second fill, does not always contribute as much color as one would think. Other distillates embrace the divergence of aroma from their crystal clarity. Blue Curaçao is an example of deliberate divergence of color for the sake of expressing emotion via defiance of expectation and anticipation.

To represent aromas with language, it might be helpful to think of aroma sets (which quickly spill into the flavor concept). Gin is an aroma set derived from the distillation of numerous ingredients. Bourbon can also be seen as an aroma set and we can use multiple words to express its numerous components. The idea of a set is a useful framework to help explain the attentional tension between aromas and help reveal the prized patterns of pleasure.

Aroma sets can feel like they have intervals and overtones of aroma. Overtones are essentially intervals that are so close together that we cannot easily parse them. The combined aroma of orange and apricot produces an overtone that is impossible to separate, but too often we deny that realization because we know the inputs and misuse the comma as a logical operator. Orange and anise (or just about anything and anise) will produce a distinct interval. Intervals of aroma create a sensation of depth in the olfactory experience which can be a great source of pleasure. If orange, apricot, and anise, which can all be categorized as olfactory-sweet, are rendered in an imaginary spatial scale, both orange and apricot would appear close together while anise would appear distant.

Olfactory-sweetness is the easiest to manipulate in terms of creating overtones, but the same can be done for every olfactory-gustatory division. Many of the common gin botanicals such as angelica are selected to tonally modify juniper, producing an overtone that strives to be extraordinary.

Many pleasurable aroma pairings rely on creating attentional tension between different olfactory divisions. We often contrast the olfactory-sweet with the olfactory-bitter such as with the aromas of melon & smoke or blackberry & smoke. Both of these combinations will be felt to have the same shape to their tension but will seem to have different distances from each other influencing our ability to find them harmonic. The aroma set of melon & smoke is a more distant interval than blackberry and smoke. Smoke may seem a challenging harmony for melon (in the absence of another salient attentional attribute like texture) because of their distance, but other aromas sometimes are not especially harmonic with blackberry because they become overshadowed. Blackberry can be seen as relatively more dense than melon. Vanilla is typically the most dense aroma and has a large propensity to overshadow other members of an aroma set.

It is important to remember that there is no such thing as dissonance (dis-harmony). Aromas cannot not go together. It is not fair to say that one does not like something so much as one does not like something yet and tonight might not be the night to start. The idea of infinite possible harmonies was first championed in music. The avante-garde composer Arnold Schoenberg famously expressed the idea as there is “no such thing as dissonance, but rather a further removed consonance that has yet to be absorbed.” A look at musical history reveals that society has metabolized a massive amount of acoustic dissonance since the beginning of the 20th century. Adages such as “what grows together, goes together” may use the positive symbolic value of being from the same area to influence the perception of the sensory harmony in question. Flavor perception as a sensory system seems comparably atrophied and our harmonic values vary markedly person to person. Acquired tastes are immensely important to the spirits industry and yet are little understood or acknowledged.

One of the great tests for aroma vocabulary (or integrated as flavor vocabulary) is trying to describe vermouth. Most explanations of vermouth describe the origins and process of production and then end with a “you’ll known it when you see it” clause about the sensory values. Vermouth lies somewhere between wine and spirit because they are made from wine bases as well as aromatized with botanicals and fortified with distillates. When the common use tasting jargon of the wine and spirit realms are challenged to scale, they mostly fail. In defense of the jargon, many criticize vermouth for being too complex. Vermouth may have more moving parts than any other product in all of the culinary world.

If cross-modal metaphors are employed, the aroma set within vermouth can be described as an overtone of olfactory-sweetness evenly competing for attention with intervals of olfactory-dryness. The round, olfactory-sweet side features an extraordinary overtone lying in the space between the brighter muscat and the darker orange as well as a subtle interval of anise. A translucence that does not overshadow characterizes the tonality of the olfactory-sweet side. The olfactory-dry side is felt to have the shape of a terrace and in dry vermouth lies in-and-around the herbs de Provence while in sweet vermouth in-and-around cinnamon and the other mildly acrid darker spices. The gustatory-sweetness of sweet vermouth lies at a point that when diluted 2:1, spirit to vermouth, gustation seems relatively innocuous and an attentional path is flattened to perceiving aroma. The very low gustatory-sweetness of dry vermouth is such that the product can have comparable gustatory tension to dry, white table wine when constructed from a wine base (eventually fortified) that accepts low alcohol and high acid as a compromise for stable, fruity, olfactory-sweet aromas (“stable” implies aroma compounds that don’t break down and age so quickly). All vermouth is fortified with alcohol to the minimum of stability to impose as little sensory distraction from aroma as possible.

Expanded cross-modal metaphors for describing aromas may seem silly. The hyphenated descriptors may sound cumbersome and not fit for standard conversation, but there is room for more than the standard conversation. Specialized descriptors are useful for the back rooms where spirit professionals are working to sculpt aroma, not sell it. Applying language to an experience helps build the schemas we use to parse and detect contrast. Not everyone is born into a family of distillers. Those new to the art need to develop their skills quickly. The emphasis in wine culture on turning wine into words benefits the growing skills of the taster. The same can be true for the aspiring distiller.

Understanding the dividing line between the symbolism of an experience, or essentially what it stands in for, and the sensory experience is immensely valuable. At some point in time distillers need to explore how something smells and tastes blindly, in the raw. Ingenuity in the aroma field requires aesthetic detachment. Detachment (from symbolism) can bring about sustainability by helping us make use of the new, the forgotten, or the byproduct. Often these aroma sources are symbolically bankrupt. Once made harmonic on sensory level, positive symbolic value can be re-attached and the entire experience made whole again. Reflect on any spirit you love, and its beauty you will see, is the composite of both its real-sensory and purely abstract-symbolic values.

That have the expanse of infinite things,

Like ambergris, musk, balsam and incense,
Which sing the ecstasies of the mind and senses.

-Charles Baudelaire

5 thoughts on “Advanced Aroma Theory Basics

  1. in “wines and liquors” (1935) p. 144 herstein and gregory describe jamaica rum. “home trade quality”, “it has a full flavor, and chemically is characterized by a higher proportion of esters of higher fatty acids. it is generally accepted that these acids result from bacterial decomposition of the dead yeasts found in distilling materials.”

    they also mention an “export trade” quality, “so high in flavoring ingredients that it is unsuitable for beverage use, as such. the chief uses are for blending with lighter rums or neutral spirits and for the fortification of hock and similar wines.”

    the esters of fatty acids referred to by holstein and gregory may be responsible for “olfactory-umami” aromas. we likely learn that those particular esters anticipate protein.

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