The Long Read: I Taste Red

by blog on June 30, 2021

Tasting is viewed – scientifically – as the reflexive response to various stimuli. It is both a mechanistic and cognitive activity. I am primarily interested in the translation of mere stimuli into detailed images and words, and how we can develop ourselves from being passive receivers into becoming active engagers and explorers.

Broadly speaking, taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor cells located in the mouth, mainly on the tongue. Taste, along with olfaction (smell) and trigeminal nerve stimulation (registering texture, pain, and temperature), determines the way we experience flavours of food and drink. Human beings have taste receptors on taste buds and other areas, including the upper surface of the tongue and the epiglottis. The gustatory cortex is responsible for the perception of taste. So, in a simplistic sense, taste in its entirety involves reception, processing and perception. It all happens in a blink of a taste bud. One can scarcely comprehend the multiple complex stages between first encounter and final evaluation.

It all happens in a blink of a taste bud. One can scarcely comprehend the multiple complex stages between first encounter and final evaluation.

Firstly, let’s examine the taste equipment itself. The tongue is covered with thousands of small bumps called papillae. Within each papilla are hundreds of taste buds.  There are between 2000 and 5000 taste buds that are located on the back and front of the tongue alone. Others are located on the roof, sides and back of the mouth and in the throat. Each taste bud contains between 50 to 100 taste receptor cells.

Taste receptors in the mouth sense the five taste modalities (as they are known): sweetness, sourness, saltiness, bitterness and savouriness (also known as umami). Each receptor type is distributed across all areas of the mouth. Repeated scientific experiments have demonstrated that these five major tastes exist and are distinct from one another. Taste buds are able to distinguish between different tastes through detecting interaction with different molecules or ions. Sweet, savouriness, and bitter tastes are triggered by the binding of molecules to receptors on the cell membranes of taste buds. Saltiness and sourness are perceived when alkali metal or hydrogen ions enter taste buds, respectively.

The basic taste modalities contribute only partly to the sensation and flavour of food in the mouth. Other factors include smell, detected by the olfactory epithelium. The olfactory epithelium is part of the olfactory sensory system, whose role is to pass along smell sensations to the brain. It does this by trapping odours that pass across the cilia, then sending the information about those odours to the olfactory bulb.  The olfactory bulb is located in the front area of the brain. After the olfactory bulb receives information from the cells in the nasal cavity, it processes the information and passes it to other parts of the brain.

On wine courses, we are always told that what we taste is effectively what we smell, in the form of retronasal response.

There is also the matter of texture, detected through a variety of receptors; temperature, detected by thermoreceptors; and “coolness” and pungency through chemesthesis. There are also other sensations that are more difficult to quantify.

When we recognise the presence of a perceived fault, our brain tells us to find it “disgusting”.

Let Jamie Goode take up the explanatory cudgels (he is writing about the vexed subject of mousiness in wines):

The source of this variable sensitivity isn’t clear, but it seems that some of it may be due to the way our mouths are all a bit different. The pH of our mouths varies, as does our rate of salivary flow. So, when a sample of wine is in the mouth, the time it takes to change pH enough for the mousy compounds to be smelled will differ quite a bit. But as well as inter-individual differences in mouth pH, the pH of our own mouths can differ quite a bit – by as much as 0.9 units – depending on the time of day and what we have eaten. This brings a degree of imprecision to the detection of mousiness, but this is, in reality, the same as with all wine faults. It isn’t an exact science.

As the gustatory (concerned with tasting or the sense of taste) system senses both harmful and beneficial things, all basic taste modalities are generally classified as either aversive or appetitive, depending upon the effect the things they sense have on our bodies.  Sweetness, at a most basic – primal – level, helps to identify energy-rich foods, while bitterness serves as a warning sign of poisons. However, as the saying goes, tastes change, and learning and experiences will help to alter the nature of the response. Dryness in wine is now seen as a positive attribute, as is the impression of saltiness (as in the mineral salts our tongues pick up from certain wines). Wine courses instruct us in what is clearly desirable or undesirable in a wine. When we recognise the presence of a perceived fault, our brain tells us to find it “disgusting”. Yet many faults are no more than deviations from the middle way, whereas other so-called faults may actually season the wine with their particular aromas or flavours. It is the taster who determines their own tolerance for these.  Our bodies also have different sensitivities to the various taste modalities, and our brains furthermore may confuse our sense of taste by creating false perceptions. As a sommelier, I was constantly asked for a wine that was “sweet like a Sancerre”, where sweetness in this case was conflated with aromatic fruitiness rather than actual sugar levels in the wine. The thing is if your brain tells you that something is sweet, you almost certainly perceive it as sweet. (We will return to this shortly).

The primary gustatory cortex is the brain structure responsible for the perception of taste. It consists of two substructures: the anterior insula on the insular lobe and the frontal operculum. The neurones in this region of the brain register the different taste modalities and encode their intensity.

This insular cortex is involved in, amongst other things, flavour identification and plays a significant role in deciphering what our tongues are telling us. One research study made the following discovery: “… by using new techniques that analyse fine-grained activity patterns, [they] found a specific portion of the insular cortex – an older cortex in the brain hidden behind the neocortex – that represents distinct tastes.”

Other studies have revealed that part of the problem in pinning down the taste-testing parts of the brain is that multiple regions of neurons are active whenever we’re eating or drinking something. It seems that different tastes don’t necessarily affect different parts of the insular cortex, but rather prompt different patterns of activity. Those patterns help the brain determine what it’s tasting.

For example, one particular section of the insular cortex was found to light up – in terms of neural activity – whenever something sweet was tasted. It’s a literal sweet spot, in other words, but it also showed that different brains have different wiring.

“While we identified a potential sweet spot, its precise location differed across people and this same spot responded to other tastes, but with distinct patterns of activity,” remarked Adam Anderson, professor of human development at Cornell University and senior author of the study, published in Nature Communications.

“To know what people are tasting, we have to take into account not only where in the insula is stimulated, but also how.”

A lot of research has gone into showing just how strong a role the brain plays in perceiving taste. It used to be thought that receptors on the tongue did most of the taste testing, but now it seems the brain is largely in charge of the process. The conclusion is that while the tongue does identify certain chemicals, it’s the brain that interprets them.

The new research adds even more insight into what’s going on in the brain in humans when we need to work out what we’re tasting – and shows just how important a job the insular cortex is doing. Professor Anderson again: “The insular cortex represents experiences from inside our bodies. So, taste is a bit like perceiving our own bodies, which is very different from other external senses such as sight, touch, hearing or smell.”

***

However we encode and decode stimuli, however we conceptualise flavour, the act of tasting is certainly a complex activity. Our brains are busy organising information from the moment we first focus on the wine. Our initial encounter with a wine is normally a visual one (although the auditory stimulus of a cork popping or the suggestive whisper when a crown cap is eased off certainly also sets up gustatory expectations). Even if we are only looking at the colour of the wine in a seemingly passive sense, we are still receiving data that wants to be processed – and is being processed – at a certain cognitive level.

What we taste is profoundly influenced by what we see. Our perception of aroma and flavour are affected by both the hue and the intensity, or saturation, of the colour of the food and drink we consume.

Change the colour of wine, for instance, and people’s expectations — and hence their tasting experience — can be radically altered. Sometimes even experts can be fooled into thinking that they can smell the red wine aromas when given a glass of what is actually white wine that has just been coloured artificially to give it a dark red appearance.

Colour can even be used to modify people’s perception of a taste that is already present in the mouth. One can, for example, appear to make food or drink taste sweeter by adding a pinkish-red dye. A food or beverage company might be able to increase perceived sweetness by up to 10% by getting the colour of their product, or the packaging in which it comes, just right.

Surely psychologically induced sweetness must taste different from the chemically induced kind? Well, the results of side-by-side tests show that people will sometimes rate an “appropriately-coloured” drink (imagine a pinkish-red drink) as sweeter than an inappropriately-coloured (say, green) equivalent drink. Such results can be obtained even if the latter drink has as much as 10% more added sugar. In other words, psychologically-induced taste enhancement is indeed indistinguishable from the real thing – at least sometimes.

Is it that participants simply cannot fully discern what that flavour is, and so rely on visual cues to help inform their decision? Or does colour actually change the experience of taste?” Charles Spence, head of the Crossmodal Research Laboratory at Oxford University, says that the answers can be found in our neurological activity. “Over 50% of our cerebral cortex is devoted to visual processing while only 1-2% is involved in taste. As such, our brains rely heavily on visual information, particularly colour, to anticipate and organize our experiences of foods. However, colour information doesn’t simply act on our brains, our brains act on colour information, drawing on years of conditioning to predict future experiences.”

Spence says that experts used to believe that, “all this information comes from outside through our eyes, ears, and tongue and works its way up through the cortical hierarchy, at each stage being condensed”. It turns out that there are more pathways going from the inside out. In other words, if we encounter a ripe red tomato, our brains have a back catalogue of previous experiences with ripe red tomatoes that sets our expectations well before we taste the fruit and this information becomes part of our eating experience. If the tomato doesn’t actually have the sweetness we expect, our brains can compensate for that lack by shutting out unwanted information and, on an unconscious level, ascribing a sweetness that isn’t truly present because we innately want to create a cohesive narrative of our gustatory experiences. Similarly, if we are presented with an orange-coloured cherry-flavoured beverage, our brain is invested in experiencing it as orange, discounting the cherry flavour information and replacing it with the information that is consistent with our expectations.

As Dunovan, Tremel, and Wheeler write in a 2014 study published in Neuropsychologia:

“Anticipating a forthcoming sensory experience facilitates perception for expected stimuli but also hinders perception for less likely alternatives. Recent neuroimaging studies suggest that expectation biases arise from feature-level predictions that enhance early sensory representations and facilitate evidence accumulation for contextually probable stimuli while suppressing alternatives.

There is a pre-existing database of expectations that each person carries with them and offering items that fall into an ongoing narrative of gustatory experiences.”

 

***

Our response to wine is evaluative in that it is based on what we have learned from previous wine experiences. As has been proved, putting things in connected narrative boxes may be convenient, but can also be potentially misleading.

When we think of tasting wine, we are talking about a mechanical process, the taking of wine into the mouth, rolling the liquid over the tongue, allowing it to touch and activate the taste buds, chewing it, assessing acidity, sweetness, texture, tannin, weight and the other components of the wine and inhaling air to help aromatise the flavours. This method of tasting is tantamount to extracting raw data as a precursor to an evaluation based on aesthetic criteria. The evaluation, in theory, takes place at the very end when all the data is analysed.

Yet, this is not really the case.  Take, for example, a very well-known critic who came to a growers’ tasting our company held a few years ago, methodically tasted and took detailed notes of most of the wines being poured. When I read these notes which were published later, I understood that the person in question had very particular expectations about how certain types of wine (grape varieties, regional styles) should fall within a precise flavour profile. It becomes a case of not “what am I tasting”, rather “this wine does not accord with many other wines that I have tasted from this particular grape variety.” The brain has set the taste parameters in advance of the actual experience.

Outside the tactile sensations referred to, can I actually taste red? When I see red, I am perceiving the wine in question through a red lens, as it were.  The eye is sending the red image via light-sensitive cells to the sensory neurone/optic nerve which in turn connects to the brain or CNS (central nervous system). All kinds of associations (physiological and aesthetic) come into play, so that when the liquid itself comes into contact with the taste buds, we are almost conditioned to taste red and all that red entails.

On the menu at The Fat Duck restaurant in Bray, there used to be intercourse (amongst many) where two jellies were placed on a slate. One was orange in colour, but made from beetroot essence, the other beetroot in colour but made from orange. When you tasted the orange-coloured one, you tasted orange (similarly with the beetroot). Because we are highly visual creatures, we use these simple cues to make instant assumptions and taste the evidence of our eyes.

In 1980, a study was published in The Journal of Food Science that remains one of the most significant pieces of research on the effect colour has on how we perceive, identify, and, ultimately, experience food and drink. Using a series of experiments designed to examine the relationship between colour, flavor, and food identification, the researchers made some remarkable discoveries regarding our perception of foods:

  • Experiment 1: Subjects were asked to identify the flavour of four different fruit-flavoured drinks while wearing red eye-goggles in a room with red fluorescent lighting, making it impossible to distinguish the colour of the drink. While 70% of participants were able to correctly identify the grape-flavoured drink, only 20% of participants were able to identify the orange-flavoured drink, even though 100% of them identified all of the beverages correctly under normal lighting conditions.
  • Experiment 2: Participants were asked to describe the flavours of beverages that had their typical colour additives removed and replaced by atypical colours. The researchers found that “inappropriate colouring … induced flavour responses that are normally associated with that colour.” In other words, the participants perceived an orange-coloured, cherry-flavoured drink as tasting like orange, not cherry.

Whilst most professional wine tasters excavate far deeper than the basic colour of the wine, suppositions and associative deductions naturally flow from that initial response to colour. With a particular colour in mind, a set of images and words begins to form. If we see red that will act on our brain, we will perceive and then taste red, channelling our experiences of red into a linguistic compartment and pour the appropriate descriptors into it. How we format the information is down to our individual neural wiring. One person may perceive nothing more specific than red berries; another might recall a specific berry tasted on a specific occasion.

Our tasting education creates the framework whereby we register intensity, clarity, cleanness and separate the five taste modalities, and also equips us with a highly specific language to describe our experiences. If, before we taste a wine, we are given other information such as grape variety, region of origin or even grower, we may make certain taste assumptions based on that information. Our brains will seek out, or try to find, the tell-tale signs to confirm a priori information stored about that grape, that place, that vigneron. As some of us are suggestible, we act more-or-less on the information that we are given.

Preconceptions govern what we do with the information. If we are told that we are about to taste a Sauvignon Blanc, we access previous experiences of tasting Sauvignon and what we have learned about the character of the grape variety. This is the picture that we carry in our minds and the expectation attunes our taste buds accordingly. Tasting the wine, therefore, sets up a tension between what is chemically present on our taste buds and our cognitive expectations.

As with our famous wine writer, these expectations create a corrective or hierarchical framework that sorts wines into good or bad, right or wrong.

Organising information is a form of summarising or bullet-pointing, and those adept at this process tend to be tasters who set their structured knowledge-accumulation before the actualité of the wine. A different approach might be to “feel” the wine in question. This would involve closing one’s eyes (in a metaphorical sense), and switching off (as far as possible) the intellectual preconceptions which colour one’s appreciation of the wine. Doing so will help to activate a different set of sensations– apprehension, uncertainty, excitement and the exploratory instinct. The internal focus shifts from getting the wine right (as in decoding the informational cues in front of our eyes), to meeting the wine on its terms, allowing oneself to receive sensations and impressions, to go with the flow – for want of a better expression. This response may activate a wilder, more individual/free associative semantic network, using words and phrases outside the norms of wine-tasting convention. These moments of excitement, felt on the pulses but not realised in conventional language, have the capacity to become transformative epiphanies.

***

In Shakespeare’s play A Midsummer Night’s Dream, the character of Bottom has his head magically transformed into that of an ass. When the spell is broken, Bottom describes the experience as being like a dream – a dream completely beyond human understanding:

‘The eye of man hath not heard, the ear of man hath not seen, man’s hand is not able to taste, his tongue to conceive, nor his heart to report what my dream was.’

Bottom’s use of synaesthesia here –with his references to eyes hearing and hands tasting – reflects just how confusing and disorienting he found the experience of being magically transformed.  Thus, it is when we surrender our senses, as it were. As rational humans we try to make simple sense of our experiences and build a logical narrative using a multitude of perception filters. Epiphanies can be as disconcerting as Bottom’s sense of a disequilibrium and may be outside the scope of our abilities to render them into words. The first time I sat in front of a large Rothko canvas, I found myself swooning in the sensation of moving colour. The canvas was red (of course!), and I was experiencing the motion – and emotion – of redness, both within and without the canvas. When we taste wine in an organised fashion, we view the colour as straightforward and unambiguous; we taste the wine as a clean-lined representation of that colour circumscribed by the wine glass and by the purpose of the product (to use that most horrible expression), whereas an explorer may see beyond the colour and thus taste outside the box. When I had my first taste epiphany in Harris, I felt turned inside out, dizzy in space, a kind of metaphysical intoxication. I was not in a conventional surrounding – at a dinner table or in a tasting room, nor was I confined by expectation, my knowledge of wine being extremely limited. In short, I was open to vivid experience.

The seasoned taster and the imaginative explorer are using different filters, perhaps even using different parts of their brains to assess and perceive wine. The wines that have moved me most, prompt me to allow myself to be taken out of myself, even momentarily, and perceive those wines with what the Romantic poets would call “the inner eye”. If that sounds like a contradiction, it isn’t. A wine, a great wine, is the catalyst to a reaching-out, but the energetic impulse must also come from within. These energies mingle, and, depending on their intensity, trigger an epiphany.

What distinguishes humans perhaps from other animals is a need for mental or spiritual nourishment. Eating and drinking to satisfy hunger and thirst is one thing, tasting wine to stimulate pleasure centres is something else entirely.

The rigidities of disciplined tasting may give the taster a modicum of satisfaction (such as from the incremental enhancement of knowledge); a more consuming pleasure is receiving and digesting new experience and allowing oneself to be changed. The power of the epiphany lies at the intersection of the received experience and the creative/imaginative response to that experience. It can be the fuzzy awareness of a feeling(s), it can form the basis of future memories or it can generate a highly-evolved linguistic response. The detonations in the mouth generate neuronic salvos that may even lead to a heightened state of awareness.

It would be dull indeed if human beings were viewed as glorified processing machines, the sum of genetic instincts, experiences and the product of teaching. The reassertion of our individuality perhaps lies in the fact that we have the ability to think and feel for ourselves and unlearn what we have been taught (or to go beyond it). The way we perceive and respond to tasting wine is further coloured by a variety of factors: our needs; our moods; our health; the weather; the food; the company that we are with; the sharpness of those tingling taste buds and the wherewithal of the wine itself, that liquid which is no ordinary beverage, but a complex result of chemical, physical and microbiological transformations.

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