What role do knowledge and experience play in the appreciation of wine? Why do professional tasters apprehend—or appear to apprehend—more in a glass of wine than casual wine drinkers? And why do so many people have trouble accepting the very possibility of wine expertise? Drawing on the latest findings in neuroscience and psychology, Professor Barry C Smith attempts to establish the full extent and limits of wine tasting, challenging the currently fashionable, skeptical view of connoisseurship, and explaining why it is such a difficult skill to master

Professional tasters will tell you that despite providing an occasional source of joy, tasting wines is hard work. It takes concentrated effort to get to grips with the liquid in the glass, to fix its character in mind and come to a judgment about its quality. Skills are needed that developed gradually over time and had to be learned. There is always room for improvement, and the tasting of new wines offers opportunities to gain more knowledge and experience.

By contrast, many people find the idea that wine tasting is hard and that we have to learn or be taught how to taste as fanciful as the idea of being taught how to see or to hear. Nothing could be easier than tasting foods or drinks. Sensations of taste begin as soon as food or drink enters the mouth. We sip or chew, then swallow. The sensations are fleeting and transient, which admittedly makes them hard to concentrate on, though they make their presence felt by leaving us with impressions of liking or disliking. So, is wine tasting really that hard?

The difference between these two perspectives on tasting is surprising. They leave very little room for one another’s view, and yet they are based directly on the personal experiences of the respective tasters. So, who is right? They are both wont to express a certain incredulity about the other’s stance on tasting, but the very different way in which they diagnose their disagreement offers us a potential insight into the recent spate of articles professing skepticism about wine expertise.

According to wine professionals, the social drinkers’ experiences of fine wines will be different from their own because causal drinkers haven’t yet learned to discriminate and attend to the qualities and characteristics of a wine in the course of tasting it. However, on the basis of their own experiences, wine skeptics find it unintelligible that fellow social drinkers fail to pick up on the subtle properties of wines, and it is assumed instead that the wine expert and the wine novice will experience the same wines in roughly the same way. This calls for a different explanation of the supposed advantage of the wine-professional claims. Leaving aside self-delusion or the mutually reinforcing posturing of the wine world, a more favorable explanation can be given in terms of the professional’s greater knowledge of the grape, the producer, the vineyard, and the production responsible for a particular bottle.

Let’s explore the part that knowledge plays in the following tasting notes, all taken from issue 48 of The World of Fine Wine. Here is Michael Edwards on the 2013 Adami Col Rive di Soligo Brut Prosecco Superiore, which he notes is from “one of the highest sites in Valdobbiadene, at 1,640 ft (500m) altitude”:

Pale and pristine, a stream of tiny lace-like bubbles. One senses the altitude and the scents of mountain flowers and plants. The palate has electric charge, a driving energy, propelling, yet with the subtlest completeness and douceur of the Valdobbiadene terroir.

And Michael Schuster on the 2014 Château du Tertre:

A particularly sweet flavor, harmonious, fleshy, long and gently spicy (all that Petit Verdot?), giving it a suggestion of the northern Rhône, and with delicious fruit length.

Essi Avellan MW on the 1982 Clos des Goisses:

The June 2009 disgorgement is remarkably youthful. Fresh, waxy, ginger nose. It has a curious Fino Sherry note to it. Spirity with a VA lift. A powerful palate, massively structured. A vintage high in Chardonnay. Curious, but it works.

Finally, Andrew Jefford on the 2010 Collemattoni Brunello:

Very low acidity for a Tuscan site, and a paean of praise to the ripeness of the vintage. I think it is completely and utterly delicious, and those tannins provide all the balance you might want, but it is not a wine I’d recommend to a classicist.

The skeptic may suspect that these wine writers have convinced themselves that they are tasting things in the wine that they expect to find there because of their knowledge of the vineyards, the vintage, the varieties, or bottlings. Likewise, social drinkers are puzzled by the idea that more can be tasted in a wine than is immediately available to them at first sip, and they tend to regard wine writers’ descriptions as fanciful. They trust their senses and are doubtful when others claim to see more, hear more, or taste more than they do on the basis of an assumed expertise. It’s not that they doubt wine writers know a lot about the wines being tasting and can tell us a lot about viticulture and vinification; rather, they are suspicious of wine writers’ claims to taste such things in the wine. After all, if these qualities really are present in the wine, why doesn’t everyone taste them? Without an explanation of how normal perceivers can miss certain features in a wine or in their experience of it, and of how knowledgeable tasters can extract more from their experience of the same wine, social drinkers suspect that in response to similar sensations in the mouth, wine writers simply produce an elaborate brocade of words to embellish their experience.

The what, who, and how of tasting

What needs to be established, then, is the full extent and limit of wine tasting. So, just what can you taste in a wine? This is really three questions. What can you taste in a wine? What can you taste in a wine? What can you taste in a wine? We can call these the what, who, and how of tasting, and the answers to these questions will have a bearing on one another. For what can be tasted may depend on who is doing the tasting. Do experts taste things that novices can’t? And are the differences between what experts and novices taste in a wine due to differences in how they taste it?

Wine experts will answer yes to both of these questions. So let’s look at the evidence. Do experts have highly refined perceptual capacities capable of making subtly fine discriminations of taste? And do these capacities give experts greater perceptual acuity that novices? Not necessarily. As Dr Dominque Valentin and her colleagues from the Centre des Science du Goût et de l’Alimentation in Dijon have repeatedly found, wine novices can perform just as well as wine experts at perceptual discrimination tasks; they simply don’t know they can. Before doing the tasks, they will say that they are no good at such tests; and afterward, they typically believe they have done badly, even though that’s not the case. According to Valentin, the difference between experts and novices is due to knowledge. Experts know they can make such discriminations and so are able to organize their knowledge better. This gives them an advantage over novices. But how, precisely, does knowledge effect a difference in their tasting experience if there is little difference between the perceptual-discriminatory capacities of experts and novices? And why do novices fail to pick up on characteristics of a wine that they should be able to discern? These questions bring into focus the puzzle of wine tasting that concerns us.

Inexperienced tasters assume that a wine is as their immediate sensations disclose on first sip. There is no more to be discovered and no gap between what is being tasted and their experience of it. The experience of wine professionals is very different. Winemakers, buyers, writers, sommeliers, and enologists, for their different reasons, all engage in prolonged acts of attentive tasting that stand to everyday tasting as looking stands to seeing, or listening to hearing. It would be helpful if we were able to mark this contrast linguistically. Savoring comes closest, though the term suggests approval or liking, which need not be present when carefully attending to a difficult wine. Liking is important, of course, but it is also a distraction, and as we shall see, there are theoretical and empirical reasons to distinguish the discrimination and identification of a wine’s components from our hedonic responses to them, however difficult that might be in practice.

By contrast, social drinkers are more likely to latch on to the hedonic dimension as if the whole point of tasting was to arrive at a verdict, thumbs up or thumbs down, about whether they like or dislike what they’re drinking and whether they want to go on drinking it. Wine professionals, on the other hand, need to focus on assessments of quality not preference, and they do that by attending to properties like balance and harmony between the component parts of the wine, and elegance and finesse for the ensemble of elements. How do such experienced tasters learn to get at these properties, and why do novices not immediately pick up on these properties in a wine? Are the differences between what experts and novices taste in a wine due to differences in how they taste it? How does the act of tasting and the knowledge proficient tasters have of a wine affect what they can taste in it?

For any wine worthy of our attention, the experienced taster feels there is something to work out about the wine, something to get closer to and, in some sense, to get right. The way to make sense of this thought is to suppose that there are objective flavors in the wine to discern. Expert tasters need not always agree about what these are, though the claim to truth and objectivity about a wine’s flavor does not entail that it will be known to everyone—that it is to confuse metaphysics with epistemology. Nor will experts all agree on what the flavor of a wine is. Objectivity makes room for the possibility of disagreement—for there being something to be right or wrong about—instead of surrendering to the maxim de gustibus non est disputandem. Not everything in a wine is accessible to just anyone. Objectivity involves a mixture of modesty and presumption; we don’t always discover the true flavor of a wine, but we sometimes do.

Our way of knowing about wines involves both perception and judgment; the latter requires us to come to a view, and it need not be a single view. Interpretation is needed at each stage: a way of making sense of what we’re getting from the glass, and what it tells us about the process and conditions that went into making this wine, its stage of development, and its future evolution. Knowledge guides that interpretation, probes the tasting experience, and sets questions for the received sensory impressions to answer. Without the knowledge to pose the questions, we may be oblivious to the significance of the sensory impressions we are in receipt of as tasters.

Same impact, different resonances

Novice tasters are often focused on the sensations that are occurring in them rather than on what those sensations can tell them about the wine in their glass. Thus, inexperienced tasters often say they don’t like the taste a young Bordeaux or Barolo gives them, by which they mean the astringent feel of the tannins. However, once they know that the feel—not taste— is due to the tannins (polyphenols) from the skins or the oak and they pay attention to their abundance, coarseness, or fineness, their experience starts to move outward away from the feeling in their mouth and toward the structure of the wine. Eventually, they will come to have the experience of feeling the tannins in the wine, of discerning its shape and texture. In that way, their perceptual experience comes to be about the wine, not themselves and their subjective response to it.

Repeated exposure to the act of tasting, augmented by knowledge of what one is tasting can transform experience in this way. Similarly, knowing something about the variety, about the vintage, about the style of the winemaker can set targets with respect to the expected tannin level in a wine that the subsequent mouthfeel can confirm or deny. In this way, the same sensory impact delivered to the expert and the novice has different resonances. To one, it discloses something about the wine, the winemaking, the region, and the vintage, as it does in Andrew Jefford’s tasting note above; while to the other, it imparts a particular pleasant or unpleasant mouthfeel. Knowledge of the grape varieties used leads Michael Schuster to attribute the gently spicy sensation to Petit Verdot and to find a similarity with Rhône wines, while knowledge of the long temporal gap between bottle fermentation and disgorgement leads Essi Avellan to attribute the fresh acidity detected on the tongue to the youthfulness of the Champagne. In these ways, knowledge enables one to interpret one’s sensations as a guide to characteristics of the wines, or to set expectations that our sensory expectations can confirm or revise. Knowledge changes what we can do with our sensations as we move from perception to judgment. It also allows us to organize and categorize our perceptions, to make features of a wine stand out, and it allows us to probe our perceptual experience analytically to note which items of given categories are present. In all these ways, it effects a change in the way experts and novices experience a wine.

There is also technique and the method of tasting. Social drinkers soon get down to what they see as the important part of the process: sipping and swallowing. But wine professionals go through an elaborate ritual of eyeing, nosing, sipping, and sometimes spitting rather than swallowing. This is important when we compare their respective?experiences of the same wines.

It’s instructive to ask where the experience of a given wine begins and ends for each of them. Is it when you see and hear the liquid being poured into the glass? When you pull the cork from the bottle and sense the earliest hints of an exotic scent? Or does it begin much earlier, when you go to fetch a cherished bottle with a keen sense of anticipation? And how long will your impression of the wine endure—not just on the finish, but in the memory? Can you still recall it with force and vividness as time recedes? All this can be affected by the attention you give to a wine when you’re tasting it. Tasting requires attention and concentration. Great wines may capture, may command, our attention; everything is stilled, and we are transfixed by the intoxicating power of the wine. But not all wines can do this, and when faced with a lesser wine, we must engineer the circumstances with which they have to compete, removing all sounds and sights and smells, until the only thing that stands out from this dull background is the wine. That’s why most tasting rooms are deliberately austere.

Wine tasting is exacting, requiring short but sustained feats of concentration. There is the quick, almost ephemeral, moment of sipping and swallowing a wine whose precise character may elude us at first. How do we capture the precise qualities of each mouthful of wine we sip? We try to focus on the different temporal stages of the wine’s travel across the palate—tasting is not a single event but a series of events with its own dynamic time course. And despite the short duration, the temporal dynamics of wines can differ considerably due to variation in alcohol level, brightness of the fruit and acidity, presence or absence of tannins, and the texture of any tannins. To appreciate the differences, we need to attend to what happens when and where—though features of a wine can co-occur, or owe their effect to their position in the overall temporal sequence. We must concentrate on the sensations at each stage without impeding the normal progress of the liquid across the palate by which the wine has its effect on us.

The whole can exhibit something untraceable to the parts, and in the case of great wines it is this holistic, elusive quality that we attend to most and that novice tasters can acknowledge through the rush of pleasure it causes. A lot happens in each tasting moment, and selective attention is required. It is therefore what we know, or choose, to attend to that makes us the kinds of tasters we are.

Preceding all this comes the practice of examining the wine’s color for clarity, signs of aging or possible overextraction. Then we nose it: still, at first, then agitated to release the less volatile molecules. This should give us expectations about what we will taste but also therefore some surprises, because we cannot detect, or predict the effect of, the non-volatile compounds on the overall perception of flavor.

Anchoring the experience

Compare this to the usual experience of a social drinker. In a way, the hardest test is the one they are most commonly confronted with: being presented with a single glass of wine and asked what they think of it. Compared to what? To their memory of past wines? It’s perhaps not surprising that, when asked what the wine is like, they will say, “I rather like it” or “I don’t like it.” That’s because they interpret the question, “What is it like?” as the question, “What is it like for you?”— whereas what we were asking was “What is it like, the wine?” A much easier task, and one that helps direct attention in the right way, is comparative tasting. We can ask tasters whether the two wines are the same or different, what differences they notice, which wines they prefer and why. Without such instructions, shy tasters may feel they are expected to come up with a description of a wine and not know where to begin. Lacking mastery of the technical and non-technical terms of wine professionals, they may feel too daunted to say anything. Even experienced tasters can feel this pressure. Hugh Johnson once gave me some good advice. Don’t start with the adjectives; start with the verbs. Ask yourself what this wine is doing.

Beyond this our favored terms may help guide our search for a feature or characteristic of a known style or wine and help anchor our experience. The idea that there is more to the flavor of a wine than we can experience at any moment commits us to the idea of there being flavors in wines for us to discover and to which our perceptual experiences as tasters are partly answerable. Some will deny that there are flavors in the wine; and others may believe that flavors are created by the language we use to describe them. But we need not, and should not, think of flavors in this way. Without supposing that experts have developed the capacity to perceive the flavors in wines, it would be hard to make out the systematic differences between the experiences of wine had by experts and novices. If their experiences differed because everyone’s experience of a wine differs, being individual and subjective, this would be grist to the skeptic’s mill. Moreover, words don’t create flavors; that’s a hangover from the now outmoded postmodernism that supposed language was created by reality. It is true that we are both reading into, as well as reading off from, our experience, and we use our terms for aromas and flavors to do that. But on the whole, language can only shape our experience; it cannot create what experience discloses to us about a wine.

The most multisensory experience

What can attentively conducted tasting experiences disclose to us about the characteristics and qualities of a wine, and how much do we know about experiences from a sensory point of view? How many senses does it take to taste a wine? We know from recent findings in neuroscience and psychology that our senses don’t operate in isolation but interact to produce unified multisensory experiences, and tasting experiences are no exception. In fact, tasting may be the most multisensory of all our experiences arising from the brain’s integration of inputs from touch, taste, smell, as modulated by other modalities like vision and audition. Looking at the color of a wine in the glass not only generates expectations but can alter how sweet or sour a liquid is perceived as being. For evolutionary reasons, red suggests sweetness and green suggests sourness. Even the sound the wine makes when poured from the bottle can create expectations. We can, surprisingly, distinguish just by hearing whether we are listening to the sound of club soda, Prosecco, or Champagne being poured from the same shape of bottle into the same type of glass. The brain has encoded this information, and when activated it gives rise to expectations that condition subsequent experience.

When it comes to tasting, most people think they taste with their tongue. However, the tongue contributes very little to our tasting experiences. All the tongue provides are the tastes of salt, sweet, sour, bitter, umami (or savory), metallic, and perhaps fatty acid. These are the basic tastes for which there are distinctive classes of stimuli—salts, acids, sugars, bitter compounds, glutamates; independently perceptible taste qualities, like sourness; dedicated receptors and separate pathways of neurotransmission to the brain. When the basic taste qualities combine, they can suppress or boost each other: sweetness suppresses sourness and vice versa, salt suppresses bitterness, and bitter and sour reinforce one another, while umami boosts all the basic tastes. The combinatory effects can produce a salt/sweet balance, as well as bittersweet and sweet- and-sour tastes. But together they are unable to explain the wide range of things we are capable of tasting in wines: lemon, lime, banana, peach, pear, raspberry, blackcurrant.

The flavors of these items are not made out of combinations of salt, sweet, sour, bitter, and umami. What combines with sourness or acidity to give lemon? There is no such taste arithmetic. Nor do we have raspberry or pear receptors on the tongue. What explains the large range of things we are capable of tasting in wines is our sense of smell, which together with touch creates the unified, multisensory experience of flavor. Touch gives us information about the temperature and texture of a wine, and also its weight in the mouth. And what we call the taste of a wine is actually a fusion (or confusion) of taste and smell, which we are unable consciously to separate into its components parts.

We are blind to the multisensory dimensions that constitute tasting experiences; they give us little clue that they result from the integration of different sensory components. That’s why we think of such experiences simply as tastes. Given the hidden complexity of multisensory flavor perceptions, it is not surprising that wine novices overlook aspects of what they experience in tasting. What’s more remarkable is that wine experts should be able to analyze certain aspects of these complex experiences into component parts. Most of the time we are unable to decompose the ingredients that make up our tasting experiences. For instance, we seldom recognize the contribution smell makes to tasting. The odor-generated fruitiness of melon is experienced as though it was coming from the tongue, and the only way to discover that it is not is to try tasting a piece of melon while wearing a nose clip. All we will get is some sweetness and the slippery feel of the flesh; though when the nose clip is removed, the largely odor-induced melon flavor rushes back in. And as soon as it does, it is utterly inseparable from the taste coming from the tongue. And yet we know that we can’t be getting that flavor from the tongue, since a moment ago with the nose clip on, the tongue detected very little. What this shows is that when taste and smell combine, they are usually fused into a single, unified flavor percept that cannot be experientially divided into distinct taste and smell components.

Common confusions

The contribution smell makes to flavor perception is not via the ordinary way we experience it when inhaling odors from the environment, or even nosing a wine. This is orthonasal olfaction. Instead, flavors are perceived when odors reach the nose from the mouth by retronasal olfaction, involving the olfactory processing of volatile compounds released from foods or liquids in the mouth by acts of chewing or swallowing. Swallowing pulses odors up to the olfactory epithelium, giving us a big flavor hit. The prudent precaution not to swallow during professional tastings means that one will not have the same or as intense a flavor experience as we would normally have when drinking this wine. Also, the so-called aftertaste of a wine is actually an after-smell, as odor molecules in the throat rise through the nasopharynx to the olfactory epithelium. The same receptors are stimulated whether odors reach the nose by the orthonasal route, or by the retronasal route. However, the brain treats the signals slightly differently depending on the direction of airflow, then projects the signals to slightly different cortical areas. As a result, we can experience odors differently when detected outside and inside the mouth. Pungent soft cheeses like Epoisse can smell rather off-putting at first, but once they are in the mouth they are delicious. By contrast, the smell of freshly brewed coffee far exceeds the experience we have when tasting it. The flavor doesn’t seem to match the aroma, and that’s partly because many of the 800 volatiles in coffee are stripped off by saliva, but also because the remaining volatiles are experienced differently when smelled retronasally rather than orthonasally. By contrast, the odor of chocolate has the same intensity and quality when sensed orthonasally or retronasally. We get what we expect, which may well be among the reasons why chocolate is so hedonically satisfying.

But before we deal with the hedonics, let us return to the absence of a recognizable smell component in the experience of flavors. Notice that the mismatch between aromas smelled orthonasally and retronasally means that nosing a wine before tasting will not tell us straightforwardly about the wine’s flavor and character. It is when retronasal olfaction combines with tastes from the tongue that we have flavor experiences. So, what we get on the nose may not be part of the wine’s flavor but only serve as a predictor, gained from many trials of going from nose to palate, of the character of the wine. Even then, we cannot predict the combinatory effects the non-volatiles detected on the palate will have in combination with sensed odors in creating unified flavors. Taste proper is restricted to the gustatory part of flavor perception that arises from receptor firing on the tongue, in the oral cavity, and in the gut (where taste receptors are also related):

The use of the same word “taste” to refer to flavor and to the true gustatory sensations of salty, sweet, sour, and bitter leads to a variety of confusions. For a clinical example, where patients lost olfaction, they often report that they cannot taste or smell. However, when questioned, patients acknowledge that they taste salty, sweet, sour, and bitter, but “nothing else.” The “nothing else” is the contribution of retronasal olfaction to flavor.1

This contribution of retronasal olfaction to flavor perception— that is, the fruity part of melon flavor—is experienced as if it were coming from the tongue. The shift in felt location is known as oral referral, on analogy with the referral of pain sensations felt elsewhere than where they originate. Temperature, as part of touch, has an impact on flavor. When a red wine is chilled, it accentuates bitterness; and for some people (called thermal tasters), a warm feeling on the tongue can give rise to a sensation of sweetness, while cold produces sensations of sourness or saltiness. In this way, cross-modal interactions between the senses modify the final summation of inputs integrated into a unified experience of flavor. The multisensory perception of flavor is not just the result of combining different sensory         elements—they interact with one another. Touch can affect basic taste qualities, and smell can affect touch. For example, velvety thick cream can taste sweet although there is no added sugar; and odors can affect how creamy something tastes in the mouth. So, viscosity in a wine, although processed separately in the brain, has an impact on how sweet one will perceive a high- alcohol wine as being.

The feel in the mouth of the astringent tannins in red wines is often confused with bitterness, and the effect can be reinforced by acidity. The confusion of one sense with another is common in flavor perception. We tend to describe the aroma of vanilla as sweet, though sweet is a taste not a smell. What is more, if you try eating a piece of vanilla pod, you will realize it is quite bitter and has no sweetness in it, and yet the perceived sweetness of a food or drink is enhanced by the addition of vanilla aroma due to an association made by the brain having experienced the aroma of vanilla being combined with sweet dishes such as ice cream, cake, and custard. However, for food cultures in the Far East, which combine vanilla not with sweet things but with salt or with fish, vanilla will smell salty.

So, why do we speak of sweet smells? It’s because the brain has learned to associate the aroma of vanilla with the sweet- tasting foodstuffs with which it is typically combined, and through associative learning we come to transfer characteristics like sweetness from tastants to odors that precede and predict them. The same goes for the sweetness of strawberries and the aromas of strawberry. Heavily oaked wines from California are often described as overly sweet, though this may, in some cases, be due to the sweetness enhancement effect whereby a liquid is perceived as sweeter when combined with an orthonasally presented vanilla odor, as well as to the high levels of alcohol whose glycerin feel can also induce experience of sweetness. Beware, then, of what you get on the nose and what it does or doesn’t tell you about the liquid in the glass.

To account for our ability to perceive methol and the CO2 bubbles in Champagne, we need to add the specific effect of chemesthesis: the irritation of trigeminal nerve endings that produces sensations of stinging, burning, or cooling associated with spices. The trigeminal is the fifth cranial nerve, serving the eyes, nose, and mouth; it is the one that makes mustard taste “hot” and peppermint taste “cool,” even though there is no change in temperature. The trigeminal stimulant CO2 in sparkling wines and fizzy sodas suppresses the effect of sweetness and accentuates sourness, making some more palatable.

The most remarkable feat in wine tasting

When we sip and swallow a wine, we experience not its taste but its flavor, which is largely due to retronasal olfaction. The term flavor picks out something perceived conjointly by touch, taste, and smell, and is used in sensory science to distinguish it from what is detected by taste proper (gustation). Recognizing the complexity of our tasting experiences provides an immediate clue as to why everyday drinkers are not fully aware of what is happening in their own tasting experiences and why they may be puzzled to learn that expert tasters—including winemakers, enologists, sommeliers, and wine writers—claim to find so much more going on in the wine when they are tasting it. But how are wine experts able to overcome the limitations conscious reflection places on us, by serving up a unified, gestalt-like flavor perception? The brain processes the gustatory, olfactory, somatosensory, and temperature inputs from food and drink stimuli separately, and yet through multisensory areas like the orbito-frontal cortex it integrates this information into a single, unified perception of flavor. What the attentive wine taster is trying to do is unpick the subtle workings of the brain to pull apart and lay bare the features of touch, taste, and smell through whose unique combination a well-made wine has its effect on us.

The challenges are considerable, especially with respect to identifying the aromas in wines of suitable complexity. Smells and tastes are difficult to segregate. Fruitiness is an odor, and sweetness is a taste, and yet novices frequently run these together. Experienced tasters know there is fruity-sweet and fruity-sour, such as the sour-cherry note in cool-climate Pinot Noirs; and yet fruitiness is only sensed olfactorily. Some will speak of grape characteristics, others will talk of esters, and it is a matter of interpretation what specific wine odors are due to and what they tell us about the condition of the wine or its making.

In focusing on what is going on in a wine, experienced tasters will be aware, as novices are not, of the dynamic time course of tasting and can selectively attend to different stages or sequences of unfolding aromas or flavors. Tasting notes will often break things down into descriptions of color, which give clues about the age or style of winemaking, reports on orthonasal olfaction followed by reports on what is discovered on the palate, which is dominated by retronasal olfaction. Here is more from Andrew Jefford’s tasting note for the wine mentioned above:

Very ripe with rather pruney fruits, but very beguiling. On the palate this is very sweetly fruited, [...] almost prune and peach, and the generous tannins are sweetly constituted, too.

Jefford is sensing odors he knows are signs of ripeness of the grapes at harvesting. The pruney odor is consistently present when sensed by both orthonasal and retronsasal olfaction, but the latter reveals further odors revealed only retronasally, like peach. Sweetness, detected by gustation, is added to the fruit odors to yield fruit flavors, and in his awareness of this unified, multisensory event, Jefford finds it is impossible to prise apart the sweetness revealed by gustation from the tannins revealed somastosensorily as a mouthfeel.

The rest of Michael Schuster’s tasting note is as instructive:

Ripe and mineral nose, medium-full, supple, yet fresh, very fine tannin.

Again, there is interpretation of the odors sensed orthonasally as due to ripeness of the grapes. There is plenty of information coming from touch, and some, such as “fresh,” from gustatory detection of acidity, contrasted with feel. The most remarkable fact about proficient tasters’ abilities is their identification of odors both orthonasally and retronasally. Odors are notoriously difficult to identify and to name. But the naming problem is not due to something anomalous about smell. We name odors by their sources: strawberry, mint, leather, cigar box. If we know the source, we can easily name the odor. The main difficulty is identifying the typical source of a sniffed odor, and this is compounded in the case of wine tasting. We learn to identify odors in the presence of their sources, and these have a look, a shape, and a feel. Bottles of clear scent or tawny-colored liquids do not resemble pieces of leather or blackcurrants; and in fact, the multisensory clues for blackcurrants or leather are not only missing but counter-indicated by clashing color, texture, and shape clues. It is the connecting of a wine odor to a source in order to produce a name for it that is the most remarkable feat of wine tasting, and it takes years of training and experience.

Some wine terms are even more obscurely related to their sources. Michael Schuster’s talk of a mineral nose adds to recent controversies about what the imprecise tasting term “minerality” refers to in a wine. (Schuster often resorts to the more specific term “gravelly” when describing Left Bank clarets.) As Jordi Ballester and colleagues have shown, different tasters identify this trait using a variety of sensory characteristics. For some, it is an aroma, very often due to reductive winemaking; for others, it is a taste, such as salinity; while others think of it in terms of a chalky mouthfeel. Jamie Goode and David Schildknecht have both insisted that it cannot signal perceptual awareness of the geological makeup of the soils in which the vines that produced such a wine are rooted. More work is needed to find out exactly which sensory systems combine to give tasters the various experiences they describe using the word “minerality” and why they all agree it is a term of praise.

Why flavors are real and necessary

Far from being simple, tasting is a complex interaction effect with a dynamic time course: not a single event but a sequence of events, enabling practiced tasters to concentrate on what happens at different times and places in the mouth. Attentive wine tasters will note what happens at every stage: in the attack as wine enters the mouth, on the mid-palate just before swallowing, and the persistent flavors on the finish. In this way, practiced tasters will get more out of the experience than beginners, who, as we noted, find it hard to focus on parts of these brief, passing occurrences—another reason why they may miss some of the sensory components of their experience of flavor.

It is through advances in perceptual psychology and sensory neuroscience that we now know much more about the complex interactions in the brain that lead to flavor experiences. The sensory science, however, does not provide immediate support for the objectivity of taste and flavor. For if flavor perception only occurs when the brain combines inputs from different senses, it would be tempting to suppose that flavors are just the creations of brains; not really there until individual brains put together input from different sensory systems. This is the predominant view in the neurosciences. Quoting Gordon Sheppard, neuroscientist Dana Small says:

[F]lavor is in the brain, not the food. It is the brain that integrates the discrete sensory inputs from the food and drink we ingest to create flavor perceptions.2

However, the mistake here is the propensity to conflate flavors and flavor perceptions (cf. colors and color perception, sounds and sound perception). Moreover, the second sentence of the quote doesn’t support the first. Small is right to say it’s the brain that creates flavor perceptions—our experiences— but it simply doesn’t follow that flavors—what we perceive— are created by the brain. Flavors are created by nature, by chefs, and by winemakers, and perceptions of flavors are created by brains as our way of keeping track of flavors in foods and liquids. So, what are the flavors in wines? We can think of them as configurations of sapid, odorous, textured properties of substances that give rise to multiple sensory experiences that get integrated by the brain into unified perceptual experiences of flavor. The exact nature of these experiences depends on the precise arrangements of textures, odors, and the tastants and irritants that generate the sensory inputs.

The flavors themselves depend on the underlying chemistry of the liquid. The compounds give rise to components of a wine’s flavor, which is distinct from the perception of a wine. How we experience that flavor is subjective. It varies not only across individuals, but in an individual across time, and across different conditions. We cannot hope to link the chemistry (the volatile and non-volatile elements) directly with people’s varied perceptions of wine. We will never arrive at laws connecting the chemistry with all the myriad variations in perception. We need an intermediate level. We need a level in between the chemistry and the variable perception—and this is flavor. Flavors are emergent properties; they depend on, but are not reducible to, the chemistry. Flavors are the things that our varying and variable perceptions try to latch on to. Each flavor perception is a snapshot of a flavor, or rather a flavor profile—something that itself evolves and changes over time. Professional tasters are taking snapshots in each of their tastings and trying to figure out what the flavor properties of that wine are and which will continue to endure or alter as the wine ages. How would the wine taste if it were a degree or two colder or warmer? They make predictions and go back to sample the same wine later to determine whether they got it right; perhaps they correctly figured out that the wine needed another hour in the glass, and needed to be one degree warmer, and that it would change as it did. Tasters are making their predictions about the flavors they expect to find in the wines.

The intermediary level—necessary as it is—gives us two tough tasks instead of one. One task is to figure out the relationship between the chemistry and the flavors that emerge. The second is to figure out the relationship between individual flavor perceptions and flavors. These two jobs need to be done independently, but they have to reach the same terminus. Having this intermediate level gives us the explanatory task of saying how the individual experiences of tasters lock on to flavors, and how wine chemistry gives rise to flavors. We cannot go directly from the chemistry to perception; we do need the middle level.

Getting closer to true flavor

To get closer to the true flavor of a wine, we rely on prediction. Think of winemakers tasting a very young wine that they know needs to develop over time. It might need to stay a little longer in barrel, or it might need to be bottled after 12 months, or 18 months. They are making predictions from their early tasting experience of what the wine will be like later, on the basis of having made many wines before, and having tasted them at both an early and a late stage. These wine professionals are building up a set of predictions about the evolving flavor profile of their wines. They make a prediction and confirm it, or revise their estimate. It is patiently built-up experience and knowledge, and when they lead to confirmed predictions, there is a sense in which they are getting something objectively right.Because there is a temporal dimension to flavors, we cannot equate flavor with what anyone tastes at any given moment. Wines have flavor profiles. As tasters, we try to know them by tasting the wine in barrel, or when it has been bottled, and after four years, five years, ten years. Through this long cycle of evolution and tasting, we come to have expectations of how the wine will develop. Winemakers know its trajectory. And the wine has that evolving flavor independently of each moment of tasting. Experienced tasters will make accurate predictions about it, and by tasting to confirm their predictions they will know whether they got it right. That won’t always happen, of course, but through error signals from our senses we can revise our expectations and improve our predictions. Wine tasting is hard, but we sometimes succeed.