The Grand Cork Experiment – stunt or science?

At the end of July, The Grand Cork Experiment was launched with as much fanfare as could be mustered in the wine media. According to an article in The Drinks Business “a space in Soho was transformed into a laboratory to test whether the pop of a cork had a more positive impact on the wine tasting experience than the click of a screwcap.” A few months later, at the end of September, the results were announced with even greater fanfare – this time in the national press. Take The Telegraph headline for example: “The great wine debate: Corks really are better than screw-tops, Oxford study finds”. And how did we conclude that corks are better? The same wine is apparently preferred if, just prior to tasting, the sound of a popping cork is played to the taster through headphones, when compared to the sound of a screwcap being opened. Right, so that is sorted then, and it’s all proved by those boffins at Oxford. Well, not really.

Firstly, let’s take a look who funded the experiment, and who else was involved. The funding body was APCOR, who “exist to promote and value cork as a raw material of excellence, and its products. We work to represent and promote the Portuguese cork industry worldwide.” That’s not a good start for unbiased research, but not necessarily a problem if the researchers are given complete control of the experiment and allowed to publish the results regardless of what they show. Charles Spence of Oxford University has a good reputation as an academic in this field, and we are told in July that he designed the experiment. But I doubt very much that he designed the whole experience that experimental subjects were exposed to. This seems to have been the work of Bompas & Parr, who were employed by APCOR. Whatever this company does in general, it is certainly more akin to marketing and brand-building than it is to science.

In the absence of any scientific report, let alone peer-reviewed paper, it seems that the best description of the experiment is given in another article from The Drinks Business. The event was clearly very showy and expensive, it was viewable through windows opening onto a Soho street, and designed to impress. Certainly it was not how scientific experiments would normally be conducted. The experimental bit comes in slide number 9 of The Drinks Business presentation: Each visitor is “placed in a chair and given headphones, before being asked to rate four wines according to their quality, intensity and how much they invoked a feeling of celebration. Importantly, the wines were served in pairs, and before each one was sampled, the taster was played either the sound of a cork popping, or a screwcap being twisted open.” Ignoring some of the silly headlines, the results seem to be best summarised by Wine Industry Advisor here: “Overall, participants rated the same wine as 15% better quality when served under a cork than a screwcap. The wine under a cork was also rated as more appropriate for a celebration (+20%) and more inciting of a celebratory mood (+16%).” This is actually quite interesting, but not exactly earth-shattering. If you give most people two glasses of the identical wine while implying that they are different they will often manage to find differences that do not exist, and here the sound of a popping cork was sufficient to swing the results a little bit in favour of the wine associated with the cork pop. But we are told nothing of the quantitative scale that was used, so the percentage increases are pretty meaningless. Neither are we told if the reported increases are statistically significant. And if the wines were actually sealed under cork and screwcap, an actual wine difference due to the closure could of course easily swamp any effect of a popping sound.

Strangely, the razzmatazz surrounding The Great Cork Experiment does not get a mention in the media articles that discuss the results – presumably because it was not mentioned in the press release. The fancy event laid on by Bompas and Parr, takes very much a backseat and, again according to The Telegraph, it is now reported that the study was not just designed by Charles Spence, but conducted “by a team at the Crossmodal Research Laboratory headed up by psychologist Professor Charles Spence”. Perhaps this is because APCOR would prefer us to have forgotten the PR stunt aspect, and the details of what happened to the participants before they took part in the actual tasting. Those details I think are rather important. They are given below….

Again referring to The Drinks Business description of the event, slides 1, 2 and 3 say that before the tasting there is “a cork workshop, where visitors can paint and play with cork”, they can “also then see (sic) the sound a cork makes by placing it in the ‘pyramid synth’, which produces different noises depending on the colour and density of the material”, and they were later “invited to partake in a ‘brain scan experiment’, which uses brain activity monitors to test how a person’s senses are triggered by the rituals associated with wine drinking”. This is really not the sort of thing you would expose experimental participants to if you were serious if determining the effect of a cork-popping sound on wine preference. It is known as priming, and I am sure Bombas and Parr knew exactly what they were doing, and how it might bias the results. What Charles Spence’s part in that was, I wouldn’t like to speculate on. Hopefully his input was restricted to the design of the actual sound-playing and tasting. But, the event as a whole was an exercise in sensory branding, to associate the sound of a popping cork with good wine. The popping cork is itself a form of priming where, to quote Wikipedia, “exposure to one stimulus (i.e., perceptual pattern) influences the response to another stimulus”. And the preamble activities seem very much also to be designed to increase the subjects awareness of cork, the popping sound, and its place in wine rituals. Fine as a piece of marketing, but science?

Cynicism aside though, if the pop of a cork really is so important, there are lessons to be learned that are unrelated to the possible superiority of any particular closure. One is that in addition to all the other ritual associated with removing a cork, contrary to current sommelier training the cork should be extracted with such vigour that the blighter does actually make a popping noise. Or perhaps, in cases where the cork is too fragile, or Elfen Safety objects to Champagne corks flying across the restaurant, perhaps the sommelier’s phone could have an app with cork-removal sound effects. Of course, the experiment also suggested that the same app might work equally well with screwcapped wines.

(Despite my best efforts to dig out information from the Internet maybe I am wrong, and the results reported in September were actually taken from a peer-reviewed paper, and based on a proper experiment conducted at the Crossmodal Research Laboratory in Oxford. Do tell me if you know that to be the case.)

Neuroenology, and I Taste Red – two book reviews

Here I review two recently published books that cover similar ground. Both describe the science of how we perceive wine. As is made abundantly clear in both books, we use all our senses in wine perception, not just smell and taste, and we integrate this information in our brain, together with memories of other wines, and what we think we know about the wine, to create the impression of what the wine “tastes like”. It is an important point.

Both books were worthwhile reading for me, and yet I found both annoying in places. They are a nice pair of books to read at roughly the same time, as Jamie Goode’s is written from the perspective of a wine writer who has read up on the science of tasting wine, while Gordon Shepherd writes as a neuroscientist making research findings relevant to wine lovers. As you might expect, the books are very different in style.

First off, let’s take a look at I Taste Red: The Science of Tasting Wine, by Jamie Goode. I got it for £10.77 including postage from Books Please, who seem currently to have the best price for books – well below Amazon prices. If I buy the book myself, I always quote the street price rather than the usually irrelevant RRP.

This is a generally very readable book, which will appeal to a lot of wine lovers, and covers the ground well, with a good emphasis on the importance of multimodal perception on wine tasting.

In my opinion though, some of this readability was at the cost of understanding the basis for a some of the information we are presented with. Jamie did explain that, in order to make the book more accessible, he did not want to include references in the text, but this meant I that I was unable to check out the evidence for a few statements that I thought questionable. In a similar way, Jamie did tend to talk about things that were assumed by wine experts as if they were facts, and I think a more critical examination of the assumptions would have been good.

Sometimes, I felt that the ground was covered a bit too broadly, in that the topics strayed well away from wine tasting, into the importance of smell for sexual attraction for example. It was interesting in a way, and I am sure deliberate, but I would have preferred a bit more focus.

Another criticism – and this seems to be increasingly common in wine writing, and journalism in general – is that there was a lot of reporting of what other people say and think, with little analysis and reflection. I would like to have seen more of an attempt to establish a consistent and reasoned view of where the truth lies.

Get this if you want an accessible book that has a broad mainstream overview of the subject.

Now on to Neuroenology: How the Brain Creates the Taste of Wine, by Gordon M Shepherd, also bought from Books Please, this time for £13.85.

This book is tougher going, reflecting perhaps that it is written by a neuroscientist, and there is a lot more hardcore science, which might put off a lot of people. It starts at a ponderous pace, mainly telling us what we are going to be told about later, but picks up momentum as you get into the book. I found most of it clear, but I did get a bit lost trying to follow the pathways of information in the brain. I think I took a wrong turn at the Amygdala. Perhaps clearer diagrams might have helped? As with Jamie’s book, there is no formal referencing system, but I felt the informal system in this book would by-and-large make it possible for me to chase up the original research if I wanted to.

This book covers the ground very well too. Perhaps in a bit too much detail in places – I am not sure, for example, that we really need to know so much about the aerodynamics of the inside of the nose. In other places however, the detailed scientific explanations are both relevant and fascinating.

The author does not pretend to be a wine expert but he has clearly spoken to some, and one in particular: Jean-Claude Berrouet of Petrus, the meeting with whom is described in an interesting appendix. But I do wonder if that meeting was a little too influential in the image of The Wine Professional painted in the book. A lot of professionals taste a lot more informally than Gordon describes.

And in a way, that leads on to a general gripe. Gordon is always at pains to emphasise the importance of each stage of wine perception – from the first sight, sniff and sip, through the mouth and nasal cavity, and within the brain – but there does not seem to be any attempt to get a handle on the relative importance of all these factors. Thus, as everything is soooo important, the wine taster is advised to do all manner of things to get the maximum sensory input from the wine. However, I am far from convinced that this turning-up-the-volume approach is a good idea when tasting, and think that it may finish up emphasising aspects of the wine that are far less noticeable when drinking properly, and not necessarily in a good way. I personally have discovered, for example, that swilling young Barolos round the mouth causes the astringency to mask the fruit, which is more evident under normal drinking conditions.

You may not know, but the same author also wrote a book call Neurogastronomy, which I reviewed a few years ago. So one obvious question is: should I buy Neuroenologly if I already have the older one? And if I were only to buy one book which one should I get? While they share some material, they are very different books. Neuroenology being very much organised around tasting wine. It certainly would not hurt to get both books, but if you really want only one, I would say wine lovers should get the older Neurogastronomy. But do note that this is a big thumbs-up to Neurogastronomy, rather than a strong criticism of the new book. You might have to do a bit more work to relate it to wine, but Neurogastronomy gives a bigger picture, some of the additional information being relevant to wine too.

Why four’s the aroma limit

four aromas

I recently had an article published in Circle Update (the magazine of the Circle of Wine Writers). It concerned the number of aromas used in wine tasting notes. If you are interested you can view and download a PDF offprint of the article here: Why four’s the limit.

It draws heavily on a four-part series of blog posts I wrote late last year. Compared with the Circle Update article, these contain more words – not necessarily a good thing – but also, in “the science” post, there is considerably more information about the scientific basis for the notional limit of only four aromas being identifiable in blends.
How many identifiable aromas in a wine – the dilemma
How many identifiable aromas in a wine – the science
How many identifiable aromas in a wine – tasting experience
How many identifiable aromas in a wine – my conclusion

How smell is like vision, and what that means for wine

Considering the very different impressions that vision and smell make on us, there are surprising similarities in how the two senses are processed before they reach the brain. And it is quite possible that these similarities may throw some light on how we describe the aromas we find in wine.

The olfactory bulb (we actually have two of them) is an elongated protuberance lying close to the underside of the brain, but attached only at the back end. The surface of the human olfactory bulb has on it some 6,000 spherical bundles of cells called glomeruli, each one being connected by neurons to several thousand olfactory receptors in the nasal cavity. When odorous compounds enter the nasal cavity, each glomerulus is activated to a greater or lesser extent, creating a pattern of activity on the surface of the olfactory bulb that is a representation of the odours detected. That pattern can be regarded as analogous to the pattern of activity on the retina of the eye when an image falls on it. In fact the similarity does not stop there, because just as the image on the retina is further processed to facilitate detecting edges and motion, the activity pattern in the glomeruli is also enhanced by subsequent layers of cells in the olfactory bulb. Examples of smell images, reproduced from Gordon M Shepherd’s book Neurogastronomy (reviewed here), can be seen below – click to enlarge and make the text legible.smell images

In the same book, Shepherd proceeds to speculate that the smell images created by glomeruli activity are similar to visual images of faces. He suggests that this explains why smells, like faces, are difficult to describe in words but relatively easy to recognise. As a result, if asked to describe a smell we need to resort to comparisons with the smells of well-known objects. Also, neither smells nor faces are processed as the sum of distinctive component parts – we tend to recognise both of them holistically, not so much by the detail as by a general impression, and the relation between the parts of the image. Only occasionally can we recognise a face if we only see a small part of it, and usually only for faces we are very familiar with.

This speculation of Shepherd’s can be plausibly taken even further, and related to how we recognise and describe wines. Regardless of whether we are nosing a complex wine or sniffing a single chemical compound, at one level in our perceptual system the result is a glomeruli smell image. I would propose that, in the case of wine, certain aspects of that smell image may remind us of the smell images of other objects – blackcurrant maybe, or lemon – which then become the descriptors we use for the wine. In some cases, the aspects of the smell image that cause us to identify other objects in wine may arise from chemical compounds in common, but this need not necessarily be the case and similarities might be coincidental. The aspects in common may be as simple as discrete fragments of the smell image, or possibly with their root in common relationships between different parts of each image. To continue with the face analogy, the identifying of blackcurrant in a wine could be like saying that a baby’s face has his grandfather’s eyes – the eyes need not be identical, but there is however something that seems somehow similar, perhaps the relationship between the eyes and the nose. Something else that has a counterpart in wine is the idea that if we are very familiar with a face is it easier to recognise it from a partial image. In a smell image of wine, presumably the types of fruit etc. we may recognise in it are only partially represented, and that could explain why it we are more likely to recognise the aromas we are more familiar with, either from the experience of the actual fruits or from other wines.

I totally accept that most of this is speculation on the part of Shepherd and me, but nevertheless I think how we experience and describe wines is consistent with the idea of smell image recognition, and an interesting way of conceptualising it. Only time and more research will be able to refute or support these ideas.

Tasting order and wine scores

It is well known that your perception of a wine is affected by what was tasted immediately beforehand. This is similar to how other senses behave. If, for example, you sit in the dark for several minutes and then expose yourself to normal daylight, it seems to be exceptionally bright until your eyes adjust. With wine, if the previous wine was flabby, your current wine will tend to taste sharp; if it is was very dry, then sweet, etc.

anon_flight

However, in addition to that effect, the order in which you taste wines can help determine how much you like them. I have already written about Antonia Mantonakis’ research, where she presented sequences of wines to consumers, and asked which wine they liked best. In actual fact the same wine was offered in each glass, but the tasters still expressed a preference. For shorter sequences (2 or 3 glasses) they tended to prefer the first wine tasted, while for longer sequences (say 5 glasses) they preferred the last one. If you are thinking “that just goes to show how little the average consumer knows about wine”, you should be chastened by the fact that those with better wine knowledge were even more prone to this bias. But how much practical significance does it have? The consumers were after all asked to distinguish between identical wines, and they may have thought any differences were very small.

Later work[1] by French researchers throws more light on this order effect. Here the experiments were performed on wine professionals  tasting in competitions that awarded medals to Beaujolais Nouveau wines. Here, in each of two competitions of around 400 wines, approximately 100 tasters scored wines on the 100 point scale, each taster being given two flights of between 10 and 12 wines. But into each tasting sequence of wines registered in the competition, the experimenters added the same wine (an unregistered one) into the first and penultimate positions. For each competition, the average score for the penultimate wine in the sequence was greater than that for the first wine: 82.99 vs 79.78 for one competition, and 83.93 vs 81.78 for the other. Those differences are not only statistically significant, but also significant from a practical point of view. To get some feel for the practical significance, note that the difference between a silver and gold medal winning scores is 6 points. Also, as the required score to achieve a silver medal was 81, in one of the competitions the position of the wine would have decided whether the wine received a bronze or silver medal.

If wine scores and medals are important to as a consumer, then you should probably be concerned about the sequencing used in tasting flights. On the other hand, if you do not pay much attention to such things, you can now add order effects to the list of reasons that justify your position.

[1] Carole Honoré-Chedozeau, Jordi Ballester, Bertrand Chatelet and Valérie Lempereur, “Wine competition: from between-juries consistency to sensory perception of consumers”, BIO Web of Conferences 5, 03009 (2015)

Solid evidence for terroir influence on wine flavour

I recently stumbled across what seems to be solid evidence for some effects of terroir on wine. It is not new research, but for some reason it had managed to elude me, and was only brought to my attention by John Winthrop Haeger’s book Riesling Rediscovered. The research is published in [1] and [2] – see end of this post. As the latter reference is available on Google Books almost in its entirety, that was my main source of information and where I found the figure shown below.

Twenty-five different Riesling vineyard sites were studied: 12 in the Pfalz, and 13 in the Mosel, Ahr, Nahe and Rheinhessen. The substrates yielding the soils of these sites included limestone, sandstone, greywacke, basalt, slate, porphyry, and breccia from the rotliegend age. The vintages 2004, 2005, 2006 and 2007 were assessed 8 months after the harvest by panels of 13-20 trained judges. The grapes were picked at optimal ripeness, as determined by the estate owners, one portion from each site being vinified as normal by the estate, and one portion subject to a standard winemaking protocol that was the same for all sites. The wine made by the estate was evaluated in duplicate, while standard process wine was evaluated in triplicate.

The results of a discriminant analysis are shown below (click on the figure to get a larger version). If I understand the point of a discriminant analysis correctly, it here means that two functions of the flavour profiles, F1 and F2, were found such that wines of the different rock types cluster when F2 is plotted against F1. Thus, if you know the flavour profile of the wine, you could calculate F1 and F2 and stand a good chance of predicting the rock type by checking where the point lies in the left hand graph.riesling_terroir_differencesNecessarily, there were many details omitted from the conference paper, so it is difficult to judge the quality of the research, but to me nothing stands out as being obviously flawed and I would assume the work is sound. As such, for me it is the first convincing evidence for the soil substrate type having an impact on flavour profile. All the other evidence I have seen has been non-blind and anecdotal, and whenever blind tasting has been used terroir differences seem to disappear, even for people who would generally be regarded as expert tasters.

One interesting question about this research is to what extent the experimental protocol was essential in revealing the terroir effect, and to what extent it would also be clear to expert but non-trained tasters tasting blind. In other words, now necessary is the training and the discriminant analysis in uncovering the important of terroir? Also, more generally, I wonder how applicable the results are to other grapes and regions.

See my previous posts on the subject to understand my mildly sceptical attitude to terroir. I think I would still describe my attitude in the same way, but it has certainly just shifted considerably in the positive direction. However, in the introduction to the article I summarise here, it is made clear that terroir is hugely important in marketing, as a unique selling proposition, and as point of interest for punters. Marketing was the driver for this research, and whenever marketing is involved my bullshit detectors start twitching with heightened sensitivity.

[1] Andrea Bauer et al, “Authentication of Different Terroirs of German Riesling Applying Sensory and Flavor Analysis”, in “Progress in authentication of food and wine”, pp 131-151, American Chemical Society,Washington, DC, 2011

[2] A Bauer and U Fischer, “Factors causing sensory variation in Riesling wines from different Terroirs in Germany”, in “Oeno2011: Actes de colloques du 9e symposium international d’oenologie de Bordeaux”, pp 1087-1092, Dunod, 2011

Daily temperature variations and wine storage

It is often stated that daily variations in cellar temperatures are more damaging to wines than consistently higher temperatures. As far as I know empirical evidence for this is lacking, but that is not to say it is necessarily wrong.

One possible mechanism could be that the resulting pressure variations pump out oxygen-depleted air, and suck in air that is richer in oxygen – or something analogous if the bottle is stored in the correct horizontal position and the cork soaked in wine. Unfortunately, I find it difficult to get a handle on how likely an explanation that might be.

However, the reason most often proffered is that the pressure variation caused by the temperature changes can loosen the cork, making it more likely to leak.  It is a lot easier to do a quick calculation to establish the plausibility of this explanation. It turns out that a 10ºC variation in temperature will result in a force of around 100g acting on the cork – see the bottom of this post for the workings. That is, for example, the force equivalent to the weight of a smallish apple.

100g apple

A better way of understanding it might be to push on some kitchen scales with a finger until they read 100g. You can then compare that with the force you need to get a cork moving when extracting it with a cork screw. Judge for yourself, but I find it totally implausible that the 100g force would shift most corks – however slightly, and however many times that force is applied. Perhaps very old corks that a cork screw would push into the bottle might be affected, but I am still not totally convinced of that either.

air pressure variation

Ah, but you say there are also pressure variations outside the bottle due to the weather, and when added to the pressure variations due to temperature inside the bottle they could be a lot more significant. Well, above are shown the atmospheric pressure variations measured at the National Physical Laboratory for 2015. It turns out that the pressure variations due to weather are about the same order of magnitude as those due to 10ºC temperature variation – again, see my workings below – and they are lot less frequent than every day, so they will not make that much difference.

So, in conclusion, I don’t know of any evidence for daily temperature variations being  worse for wines than consistently high temperatures. That does not rule out the possibility, but it also seems unlikely that those temperature fluctuations will loosen corks.

If you’re up for it, here’s…

The science bit

Gay-Lussac’s law says that for gases at a constant volume, pressure is proportional to temperature. Here the temperature must be measured on a scale where zero means absolute zero, so we will use Kelvin for temperatures. Room temperature is around 300 K, and we are looking at a temperature variation of 10 K, which is the same as 10ºC. Thus the relative change in temperature is 10/300 – around 0.03 or 3%.

Atmospheric pressure is approximately 100,000 N per square meter, and according to Gay-Lussac the relative change in pressure is the same as the relative change in temperature. So the absolute change in pressure is 100,000 x 0.03 = 3,000 N per square meter. (At this point you might also like to note that the atmospheric pressure variations shown above are also of the order of 3%.)

That pressure change acts on the area of the cork, which is about 1 cm, or 0.01 m, in radius. The area of the cork is 3.14 x 0.01 x 0.01 = 0.000314 square meters.  3000 N per square meter acting on an area of 0.000314 square meters gives a force of 3000 x 0.000314 = 0.94 N, which is approximately 100 g force.

Edit 24/07/19: It later occurred to me that although liquids generally expand much less than gases, the volume of wine is a lot greater than the ullage in the bottle, and that the wine expanding may significantly compress the air, and thus increase the pressure by more than calculated above. So I redid the calculation to take account of the above effect, and also with some other improved assumptions. Overall, including the effect of using a specified temperature change of 15-25ºC, a high-fill ullage volume, a pressure at 15ºC of 1 bar, and an expansion coefficient I found for white wine, the change in force on the cork would be 160 g. This reduces to 115g for a low-shoulder ullage. So the force is larger than originally estimated, but not one so much greater that it invalidates my general conclusions. I’m not going to publish my workings here, but let me know if you would like to see them.

Gestalt perception of flavour

coffee_cuppingGive your Man On The Street a glass of wine and ask him how it tastes, and you could well get the response “it tastes like wine”. Nothing wrong with that – it is what might be described as a gestalt perception. Wine contains hundreds (if not thousands) of chemical compounds, many of which will individually give rise to different flavours, but overall the impression is clearly recognised as wine. In the same way, when someone is shown a chair they will immediately recognise it as a chair – they won’t say there are four near-vertical sticks of wood supporting a horizontal square board etc.

It is only people who are relatively skilled in wine appreciation that will dive into a more detailed description like “blackcurrant with a hint of coffee on the finish” – and if we are honest “it tastes like wine” is arguably more useful in many circumstances. Also note that, while we might be feeling superior for spotting the nuances in our glass, we are saying one of the flavours is coffee. We have an idea of a generic coffee flavour, in the same way as many have a generic wine flavour. But coffee is another complex drink that experts analyse and describe in terms of other flavours. Worse than that: wine is a descriptor that is sometimes used in coffee tasting notes, in the same way that coffee is used for wines. So in an extreme case we could have a wine that happens to taste like a coffee that tastes of wine!

Joking apart, the idea that the human perceptual system can sometimes regard aromas that are chemically complex as a single entity, and sometimes analyse them into component parts, is an interesting one. I mentioned in an earlier post that, when considering the number of identifiable aromas in a wine, a chemically complex recognisable aroma behaves like an aroma that is due to a single chemical compound. In fact, the researchers reference other work showing that the two aroma types seem to act in very similar way even at a level as low as the olfactory bulb. But surely that cannot tell the full story. It is undeniable that, for some at least, wine does not merely taste of wine. Neither does coffee merely taste of coffee.

How many identifiable aromas in a wine – my conclusion

I have now done enough scene-setting and pussyfooting around: see my previous three blog posts (in chronological order 1, 2, 3). It’s time for me to nail my colours to the mast and say what I really think about tasting notes that mention many different aromas when science tells us we can only identify four in a mixture.

Jan_Brueghel_I_&_Peter_Paul_Rubens_-_Smell_(Museo_del_Prado)First of all, I cannot find any particular problem with the scientific evidence for our poor ability to identify aromas in a mixture, and I see no reason to doubt its applicability to wine. If anything I would expect it to be an easier task to identify aromas in the experimental situation than with wine, as in the experiment there were always subsets of the same 7 or 8 odours, as opposed to the much larger number that people find in wines.

There is a lingering doubt in my mind because the experiments presented odours only to the nose. With wine however, aromas are also detected when it is in the mouth. Does that cause a greater number of aromas to be detected in total? My personal experience suggests that happens only very occasionally, and to a small extent. However, in the tasting note example I gave in the introductory blog post for this small series, the aromas detected on the nose and palate are markedly different. I may return to this issue in the future, but my initial feeling is to go with my personal experience. And what about letting a wine develop over a few hours or days? Does that let additional aromas develop and become identifiable? It is possible, but again in my experience it is rarely the case.

I acknowledge that there is also experimental evidence that it is possible to tell if a single very familiar odour is present in mixture containing up to 12 odourants. Additionally there is anecdotal evidence of perfumers and chefs being able to detect single missing ingredients in complex familiar recipes. But these tasks are very different to identifying aromas in an unfamiliar wine.

For now, let us take the identification of an odour object in a wine literally, by which I mean that identification means there are key aromatic compounds in both the wine and the actual odour object. With this literal interpretation, I think it is fair to say that the limit of four correct identifications will apply. Indeed, the experiments suggest that even with fewer named aromas it is unlikely they will all be correct.

The literal interpretation of aromas I have just described is not totally unreasonable. Certainly in some cases it seems that the same chemical is responsible for the aroma in both the wine and the real aroma object. Rotundone, which is found in black pepper and Syrah, is one example. However, aroma objects mentioned in the tasting note may merely be reminiscent of the real thing. Or, as some less kind people might put it: imagined or made up. In these cases, there can clearly be no limit of the number of identifiable aroma objects, but by what criteria can we judge the value of such lists?

For me, the main criterion for a successful tasting note is its ability to communicate the experience of drinking the wine to the reader. And here I mean to communicate accurately; not just to give an impression of what the experience might hypothetically be.  When I am tasting, the correspondence with tasting notes independently written by others is usually minimal. I have seen no formal studies into how common this experience is, but we can also get hints by comparing tasting notes of the same wine written by different people. Usually there is little similarity, and sometimes the differences are huge. It is interesting to speculate about to what extent the differences are due to the subjective nature of taste, and to what extent it is imperfect communication; but differences there are.

Speaking personally, the tasting notes I find communicate best are those where the aromas listed are few and vaguely described. For example, it can often be accurate, and still helpful, to identify citrus fruit in a wine. But when someone else describes a wine as tasting of lemon, I often decide it is closer to lime. And does anyone actually care? It is difficult to imagine a disgruntled customer returning a bottle of wine to a shop because the type of citrus fruit was incorrectly described on purchase. The precision of description is linked the issue of the number of aromas: one person’s citric could be another’s lemon, lime and clementine. The level of detail we use in tasting notes is another interesting topic to which I might return.

In summary, as promised, here are my colours on the mast stated with an unjustified sense of certainty. There are two reasons why I am suspicious of tasting notes with a long list of aroma objects:

  1. If you take a more literal interpretation of aromas in tasting notes, it is impossible to produce correct lists containing more than four aroma objects .
  2. I am not convinced about how useful long lists are anyway. I favour a shorter tasting note that contains only the dominant aromatic components, and one that is not over-specific in its aroma descriptors.

In the words of Carveth Read: It is better to be vaguely right than exactly wrong.

How many identifiable aromas in a wine – tasting experience

I continue to investigate the number of aromas we can detect in a wine. There seems to be a conflict between scientific research, which has shown that we are incapable of identifying more than four odours in a mixture, and the testimony of wine tasters who name as many as 10 or more aromas. For the story so far in more detail, see my previous two blog post here and here. Now I will look more closely at how wine tasters come to identify so many aromas, and what it means when they do.

aroma_wheel

I know that some tasters sample their wine over the course of an evening, with and without food, and possibly even continue with the same bottle over two of more days. That is potentially going to lead to longer tasting notes, and the naming of more odours, because the wine, the context, and even the taster might change over that period, and the changes could result in different proportions of various aromatic chemicals, different chemicals becoming available to the nose in the form of vapour, and different taster sensitivities.

Other tasters however are perfectly capable of reeling off a list fruits, herbs and spices within the space of a few minutes. The people I have seen doing this have all been Americans with some level of sommelier qualification, and my preliminary conclusion is that it is related to their training and culture. In the case of professional wines critics who name many odours in a tasting note, I suspect those lists are also usually produced quickly due to pressures of time. This is a very different situation to the tasters who make their notes over an extended period, as nothing has chance to change much after the first nosing of the wine.

But do the odours named in these long lists actually exist in any real sense in the wine? Here, by “in any real sense” I mean as chemical compounds in concentrations that could stand any chance of detection. Note that Laing’s limit of four applies not to the taster’s imagination, but to the correct identification of odours physically present in the mixture as chemicals. To answer the question about whether the odours exist, we would need to perform a detailed chemical analysis of the wine.

Even if the odours do not really exist, there may be understandable reasons why they may be perceived. In Avery Gilbert’s book What the Nose Knows, there are several examples of how suggestible we are when it comes to our sense of smell, and suggestions of what we might find in a wine can come from many sources. The best known example is perhaps that the addition of red food dye to white wine prompts people to find aromas usually associated with red wines. In real life all manner of things might suggest what aromas should be in the wine, not least any hints as to what type of wine is in the glass. There is no shame in being suggestible in this manner. It is simply the way we humans work perceptually, and as we also are the ones that drink the wine does it really matter?

We must also acknowledge that odour perception is a complex multimodal process, and seemingly unrelated stimuli can affect our sensitivity to odours in ways that are not explicable by suggestibility. For example, a drop of a sweet substance on the tongue has been found to increase the sensitivity of Westerners to an almond aroma. Effects like that could also cause us to identify more odours than Laing’s experiments suggest we should.

Finally, I am convinced that some tasters fabricate flavours because they feel, for whatever reason, a few more are needed. I too would do that under certain circumstance – if I were taking some sort of test for example, and I was required to list a certain number of flavours. If you have a good idea what the wine is, it is very easy to throw in a few extra flavour descriptors that would not raise eyebrows. Claret? OK, that will be blackcurrant, pencil box and French oak then. In fact, come to think, I have done it, in a tasting competition a few years ago when I really thought the wine was so mediocre there was little to say about it.

On the subject of how many identifiable aromas there are in a wine, that is now all the detail and preliminaries out of the way. So far I have tried to be as objective as possible in describing the evidence, but in my next post I promise will stick my neck out and say what I really think. I just have to first decide what that is.