How Many Simultaneous Aromas Can We Detect in a Wine?

In Gordon Shepherd’s fascinating book Neuroenology: How the Brain Creates the Taste of Wine, he reports on some research that raises obvious difficulties for wine tasting notes that mention seven or eight aroma descriptors.

In 1989, Laing and G.W. Francis were interested in how many components a person can identify in an odor mixture…. They trained subjects to identify seven individual odors and then tested them with various mixtures of the odors. Sounds easy? …. The subjects could identify each odor separately 82% of the time, but when present in a binary mixture with one other odor, the identification fell to 35%.  With three odors, recall fell to only 14% and with four odors it fell to only 4%….

Laing and others have pursued this question in a number of studies since then—for example testing panels of expert flavorists and perfumers. The results have been similar. [151]

Shepherd suggests that the maximum number of distinct aromas we can identify in a wine is three and for most people, apparently, it’s only one or two. This obviously does not square with wine tasting practices where it’s common to identify multiple aromas in several aroma categories.

Shepherd does address this by noting that many of the properties identified by wine critics involve taste and tactile sensations along with gestalt judgments that have to do with pleasure. But that response doesn’t address the problem of wine tasters reporting more aromas than the science indicates we can sense.

I haven’t looked more closely at the methodology of these studies but Shepherd’s account of them seems misleading in at least one sense.

Shepherd seems to be overlooking the fact that wine tasters seldom form conclusions about aroma notes from one sniff of the wine. I can only speak for myself but, when I write wine tasting notes, it’s only through several well-spaced inhalations that I gain a comprehensive understanding of aroma structure. I begin by identifying one or two prominent aroma notes, then sip the wine to check retronasal impressions, and then put the wine aside for a few minutes and come back to it, checking it several times in an evening. Each time I smell I’m looking for aromas in different categories so my attentional focus shifts away from aromas categories that have already been idenfitied. The fact that only 2 or 3 aromas can be identified at one time is relevant only if the taster is in a big hurry (which they are in some contexts like wine competitions.)

In fact some of the research Shepherd reports suggests how a tasting procedure of multiple, spaced inhalations is implemented in the brain.

…when mixtures are familiar, cortical neurons treat them as synthetic objects, different from their components …After experience, the cortex has learned to treat the combinations of features constituting the mixture as a unique, complete, synthetic object distinct from the patterns of features constituting their components.

I take this to mean that once the dominant aromas are familiar, the brain treats them as a single synthetic aroma, thereby freeing up “processing capacity” to identify additional aromas. We then use memory and language to put together the holistic image of the wine. I may be able to distinguish one or two aromas in a single inhalation but subsequent inhalations provide more and more information that is synthesized via memory.

This is an argument for spending time with a wine to gain that familiarity instead of writing notes on the fly.