Category Archives: Food Science

A Neuroscientist on Wine

15 Thursday Jun 2017

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neuroenologyNeuroscientist Gordon Shepherd, author of Neurogastronomy, has a new book out entitled Neuroenology: How the Brain Creates the Taste of Wine (Columbia University Press, $25). Neurogastronomy was fascinating. I haven’t gotten to the new book yet but Harvey Steiman has a brief interview in which Shepherd makes several interesting points.

Shepherd thinks you have to swallow wine to get a full picture of its flavor and has charts on fluid dynamics in the mouth to back up his contention. Steiman disagrees arguing that

“…my experience as a taster tells me otherwise. I get no difference between how a wine tastes to me from actually swallowing it vs. slurping and bubbling it in my mouth, then spitting it out, so that I can stay (relatively) sober.”

I agree with Steiman here. I haven’t noticed that spitting lessens my perception of aromas.

Shepherd thought for a moment. “As you breathe out, those volatiles can carry from the mouth to the back of the nose. With practice maybe you can train your uvula to be open when tasting, and others can’t.”

Perhaps, but I have no such training and Steiman doesn’t mention any either. I think you have to trust the phenomenology here. If we’re not perceiving differences then there are no perceptible differences. Perhaps  this varies from person to person but the scientific hypothesis  needs to be supplemented with subjective reports.

Secondly, Shepherd argues that human beings are not particularly inept when describing aromas and flavors.

His peers get it wrong, he says, when they claim a poor connection between language and what we smell and taste. Our ability to describe what we taste is no different than describing a painting. “We can describe Van Gogh’s paintings of sunflowers. They look like sunflowers,” he says. “But it’s almost impossible to describe anything nonrepresentational in words to someone who hasn’t seen it. The same applies to music.

I wholeheartedly agree with this. In reviews of pop and rock albums the bulk of the commentary is about lyrics. Descriptions of the music when they exist are vague and general. The same with paintings. Discussions focus on what the painting is about. Descriptions of formal elements are either general descriptions of patterns of colors and lines or quickly become metaphorical and allusive.

Describing aesthetic experiences is inherently difficult and wine writers are no worse off than anyone else in that regard.

Is Flavor Intensity Destroying the American Palate?

26 Wednesday Apr 2017

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sriracha almondsThe thought occurred to me while wandering down the snack aisle at the supermarket that constant exposure to inflated flavors is destroying our ability to taste. From ginger and lime oil potato chips to dill pickle cashews to sriracha pretzel chips, ratcheting up the taste intensity scale is big foods’ ticket to higher profits. But where does it end? Wasabi guacamole? Scotch bonnet yoghurt? We quickly adapt to intense flavors so each year the intensity level must go up.

The problem is if we crave only flavor intensity the subtlety and complexity of food is passed over unnoticed.

When food technology companies put together their chemical concoctions designed to mimic natural flavors, cost considerations dictate that only the most prominent flavor components find their way into the finished product. It is expensive to manufacture the sometimes hundreds of components in an ingredient that accounts for its flavor. That’s why flavored foods seldom have the depth and complexity of natural ingredients. It’s cheap to make something hot or salty; much more expensive to re-create the genuine taste of a tomato. By learning to crave intensity we’re learning to ignore complexity and refinement.

Despite the vast flavor choices in the packaged foods section of the supermarket, they’re almost always one-dimensional. Our relatively new-found interest in flavor is being compromised by food that demands no discernment.

If you want to preserve your ability to taste it’s best to stay out of the packaged food aisle.

Misleading Headline Case #692

21 Wednesday Dec 2016

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newspaperNPR that bastion of objective reporting published the following headline on the Salt for a story that ran on All Things Considered as well:

“How Much Is Too Much? New Study Casts Doubts On Sugar Guidelines”

It makes you think that triple scoop of Baskin Robbins may not be so bad for you after all, doesn’t it.

The headline is utter nonsense. First of all, we find slipped into a sentence in the second paragraph that this is an industry-funded study. Hmm. I wonder why they decided to publish and promote this?

But more importantly, when you read the study it shows nothing of the kind. This so-called “study”, which is just a meta-study of the real science and involves no new data, shows that the science behind choosing a specific guideline about how much sugar should be a part of one’s diet is uncertain.  Should it be 5% or 10%? The science isn’t fine grained enough to be sure.

Well of course that’s uncertain. It would be enormously expensive and time consuming to do studies that would sort out with high probability the precise healthy level of sugar in our diets.

But the fact that we don’t know what the precise guidelines are does not entail there should be no guidelines at all. This bit of elementary logic seems to escape the attention of the vaunted reporters and editors at our flagship news outlet.

And did the reporter investigate to see if this meta-study left out important contrary research that might be relevant? No e

Of course, specific guidelines are going to be a best guess. That is the best medical authorities can do until we get much more data.

But nothing in the underlying data casts doubt on the role of sugar in obesity, diabetes, high blood pressure, etc.

When the history of the post-truth society is written (should there be a future in which people care about such matters) it will be media organizations that will be justly held responsible.

No one has any good reason to read or listen to these people who claim to be journalists.

Cheese, Wine and Time

14 Monday Nov 2016

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wine and cheeseFor flavor hounds, this article about cheese and wine pairing on NPR’s The Salt gives one a lot to chew on.  First, it’s nice to see the science of taste catching up to something I’ve been insisting on for a long time. The quality of tasting experience is determined as much by how substances evolve on the palate as it is on static structural relationships between elements. A new method of scientifically assessing flavor  called Temporal Dominance of Sensations (TDS) attempts to capture this dimension:

TDS is designed to reveal how the taste of something evolves as you consume it. The taster sits down in front of a computer screen with a black glass of an unknown wine. On the screen are 11 words describing attributes or sensations such as sour, astringent, bitter, floral and so on….The taster takes a sip and then clicks on whichever sensation is dominant at that moment. When the sensation changes — say, from “sour” to “red fruits” — the tester clicks the new attribute, until there is no sensation left.

The idea that it is changes in sensation that make the flavor experience interesting, exciting and satisfying has been largely ignored by flavor science. This experiment with wine and cheese is the first time I’ve come across flavor science trying to measure this dimension which to my mind is crucial.

As to the main point of the article, it claims that in general white wines pair better with a wider variety of cheeses than red wines do, contradicting  the widely accepted view that red wine and cheese is a natural pairing.

Although the researchers did not set out to recommend specific pairings, The Salt pressed Dr. Galmarini. Her latest study, as yet unpublished, does offer some advice.

“If you have many cheeses, better to serve a white wine,” she says.

It would be nice to have had a summary of the evidence for this. The article quotes food writer Ed Behr on the topic:

Behr points out that most red wines “are completely unrefreshing.” That’s fine with a little cheese at the end of a structured meal, to finish the red wine. But Behr says, when the cheese is more than just a taste but “maybe the central protein of the meal, what you want is a drink that’s much more refreshing.” In other words: a dry white.

I think that is broadly correct. But the problem I have with wine and cheese pairings is that cheese is almost always mouth coating, and this often cancels the perception of subtle nuances in wine, whether red or white. The article acknowledges this effect.

… Galmarini says there is a clear conclusion for certain sensations, such as sourness and astringency, which would probably be considered negative.

“With cheese,” she told The Salt, “the sensation is reduced. It does not last so long in the mouth.”

Right. So wines that are sour or excessively drying—bad wines—will taste better with cheese because of this mouth-coating effect. But what isn’t mentioned is that, by the same token, good wines will be diminished when paired with a mouth coating cheese.

This is not to say that the combination of wine and cheese is never satisfying. Sauvignon Blanc and a good chevre or a tawny Port with Stilton are magical. But you may not be getting as much nuance out of the wine when paired with a mouth coating cheese.

Wine Science, Minerality, and Mission Creep

02 Wednesday Nov 2016

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vineyard soilJancis Robinson has a nice article up on the hottest topic among wine geeks—minerality. (I did my own write up on it a few weeks ago.)

Jancis, like most wine writers today, finds the term useful in describing a range of flavors found in wines—wet stones, struck flint and “gaseous whiffs” for her. I use the term to refer to steely sensations and the smell of crushed rock as well.

It has been well established by science that what we’re tasting has little if anything to do with minerals in the soil. That’s fine. We’re trying to describe a sensation not discover the underlying cause of the sensation.

So it rankles me a bit when wine scientists criticize writers for using the term. Geologist Alex Maltman “went on to mock us for our use of the term gunflint, a common tasting term for Loire Sauvignon Blancs”, and “ is utterly bemused by the many bottlings nowadays that carry the name of a well-known soil type”. Dr. Richard Smart  continued in the same vein, “Does the term add to the pleasure of wine?’ he asked rhetorically, before asking us all to stop using it.“

Well in fact Dr. Smart, yet it does. It helps us describe flavor notes that would otherwise be elusive without the term and its relatives. As long as we aren’t misleading readers by claiming we’re tasting soil minerals transferred to the wine, I don’t see the problem.

It’s the scientist’s job to find the causes of wine flavors; its the writer’s job to describe experiences and communicate them. Don’t scientists have enough to do without the mission creep?

We will happily leave the science to the scientists. They should leave the poetry to us.

The Controversy Over Minerality

28 Wednesday Sep 2016

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soilOne of the most interesting debates in the wine world today is the debate over minerality. Does it exist? What is it? and Where does it come from?

The term “minerality” is relatively new to the wine world. It does not appear in Ann Noble’s influential flavor wheel developed at UC Davis in 1984. It does not appear in any of the canonical wine manuals that have formed our modern wine tasting practices such as Peynaud or Broadbent. It appears in the Oxford Companion to Wine only in the most recent edition. Yet it now appears routinely in the Wine Spectator’s tasting notes.

I find it to be one of the more useful terms for describing wine although I think it refers to many different taste experiences. The burnt matchstick flavors of Chablis, the aromas of wet stone in a good Riesling, the crushed rock aromas of a Willamette Valley Pinot Noir, and the iron filing notes of a Left Bank Bordeaux all can be described as falling under the general category of “mineral”.

But many people, especially wine scientists, dismiss the term as romantic nonsense, in part because, when the term gained currency, it was thought those mineral flavors in wine were the direct result of minerals in the soil being transferred to the wine. And indeed there is no evidence of that. Most minerals in soil have no flavor and although the roots of grapevines take up trace minerals from the soil, these do not appear to be transferred to the grapes. Wine also contains minerals such as potassium, calcium, and magnesium but these are not transferred from the soil and they also may not directly influence flavor. So there is skepticism about whether what we’re tasting has anything to do with actual minerals. On the other hand, we know soil has significant impact on flavor and we cannot rule out an indirect impact on flavor.

Despite this skepticism there is evidence that what we are tasting is real and rooted in features of the wine. Two studies described in this paper by Palacios and Molina are especially interesting. Researchers gathered two tasting panels of professional wine tasters and winemakers to taste wines selected for their minerality. After assessing the wines for their degree of minerality, the wines with the highest levels were analyzed for chemical compounds and the statistical analysis showed that high levels of perceived minerality were correlated with higher levels of free sulfur dioxide, low PH, and high total acidity with a variety of other compounds playing a less decisive, contributory role.

In a followup study, two tasting panels were given synthetic “wines” containing a variety of the previously identified compounds that seemed to effect minerality. In blind tastings using discrimination tests, the tasters were first asked to simply describe the “wines” with no knowledge of the purpose of the experiment. Then, in a second tasting, there were asked to specifically look for minerality. The purpose was to see which compounds produced the most significant perceptions of minerality.

The results:

…the presence of Succinic acid and a low pH combined with high levels of free sulfur dioxide are directly related to the use of the term minerality with a probability of 95%. The presence of Ethylphenols, m-Cresol and metals obtained a significance of 99% to relate as minerality in wine. Finally, with the same probability appears the compound Geosmin. Also the presence of Isoamyl acetate and Thiols is directly related in 99.9% with the emergence of the term minerality for the panel of producers winemakers…

Apparently there are many sources of what we call “minerality” and its perception is the result of the synergistic effect of many compounds as well as the absence of fruitiness which can cover up minerality.

At our session on minerality at the SWE conference conducted by Roger Bohmrich MW there was widespread agreement that wine such as Domaine Patrick Baudouin Anjou “Effusion”, Fritsch Grüner Veltliner “Steinberg”, and Christian Moreau Père & Fils Chablis all exhibited minerality.

Minerality may not be a direct transfer of flavor from soil to wine but there appears to be a consensus emerging that it is a useful descriptor with a foundation in the chemistry of the wine.

Why are there only 354 Masters of Wine?

22 Thursday Sep 2016

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masters of wineA Master of Wine is someone who has passed the rigorous tasting and theory exams and submitted an acceptable research paper to the The Institute of Masters of Wine. There are currently only 354 in the world. Why?

1. There are approximately 800 volatile compounds in wine that human beings are able to smell along with the 5 basic tastes that we detect in the mouth.

2. When combinations of odors and flavors are present the intensity of one is reduced by the presence of others. This is called hypoadditivity–the more aromas there are to smell the less any of them will be clearly detected.

3. We use 4 senses when tasting wine (audition being relatively unimportant unless you’re listening to music), but the input of one sensory modality can influence the others. Tastes influence aromas, aromas influence taste, color influences both, as do tactile impressions. This makes it hard to focus attention and distinguish analytically various sensations.

4. Except for detecting sugar, bitterness and spoilage, evolution has designed us to respond more readily to visual stimuli rather than aroma or taste,.

5. Assessing wines requires assigning meaningful words to sensations, a skill that no one develops naturally, and for which there is no settled vocabulary,  since it has no application outside the rarified domain of wine or food criticism.

A better question might be “Why are there so many Masters of Wine?”

The Shaky Standard Taste Model

14 Wednesday Sep 2016

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standard model of tasteI’ve long suspected, based on intuition (which is often worth exactly nothing), that the standard taste model is wrong. The standard taste model claims that there are only 5 basic tastes: salt, sour, sweet, bitter and umami. Umami was just admitted into the pantheon by Western science a few years ago. Everything else we experience as taste is a function of smell according this model. The difference between a tomato and cheese aside from basic tastes is a matter of smell (putting aside texture of course). That has always struck me as implausible.

Recently, scientists have tentatively put forward the idea that fat may be a basic taste. And now an Oregon State professor has done research that suggests we can taste carbohydrates as well.

To test the sixth-taste theory, Dr Lim and her team dissolved different levels of carbohydrates in liquid solutions and gave them to 22 participants who were asked to rate how each tasted.

“They called the taste ‘starchy’,” Dr Lim said.

Previously, many scientists believed that humans could only taste the sugar in carbohydrates, as enzymes in our saliva break starch molecules into simple sugars, leaving a sweet taste in our mouths.

But even when volunteers were given a compound to block the saliva enzyme and sweet receptors, they were still able to taste the starch – which suggests humans can pick up on a starchy flavour before it has been broken down into sugar.  Thus far there is no evidence of taste receptors for starch on the tongue so this is not a done deal. But it joins a long list of other sensations–of carbonation, a metallic flavor, and amino acids as well as kokumi, a flavor some describe as hearty—that scientists are investigating as basic tastes.

It would seem the standard model of taste is increasingly under threat.

How to Become a Better Wine Taster

08 Thursday Sep 2016

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wine studentI often here it said that people differ radically in their sensitivity to the chemicals found in wine. Either you have the natural ability to sense them or you don’t and if you don’t you’re out of luck. This is usually accompanied by the claim that our abilities differ so much that  any consensus about what a wine tastes like is illusory. But there is little evidence that this is true. It is true that some people are more sensitive to certain odors than others but evaluating a wine is seldom about detecting single molecules. Wine involves hundreds of  molecules that interact in complex ways which is not captured by measuring individual thresholds.

In most of the studies that I’m aware of there is no difference in olfactory thresholds between wine experts and novices. There are of course super tasters who can taste particular molecules in very small quantities but that usually has to do with the detection of bitterness. To supertasters the alcohol and tannins in wine are a source of bitterness and will be unpleasant. Thus, being a supertaster confers no advantage on a wine taster and may be a serious disadvantage.

Each of us is probably deficient at smelling some aroma or other—we don’t share the same package of olfactory receptors. And some deficiencies could be serious, meaning that a small minority of people just may not be very good at wine tasting. But the vast majority of people will fall into a range of normal with minor differences and there is no evidence that good wine tasters are good because they are physiologically different from the rest of us.

What distinguishes an expert from a novice, then, is not physiology but experience. If you are able to compare a present aroma or pattern of aromas to a previous experience those aromas will seem sharply delineated. If you lack that previous experience the present aroma will seem vague and difficult to sense. To become a competent wine taster you don’t have to get better at smelling; instead you have to build up a storehouse of aroma and taste memories and gain a knowledge of the types of aromas typically found in wine so you can properly label them.

In other words, to get better at wine tasting, read more and drink more.

What’s not to like.

Artificial Wine

25 Thursday Aug 2016

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synthetic wineThis is bizarre but inevitable I suppose given the popularity of reductionism is science.

Reductionism is the view that all complex phenomena can be explained by analyzing them into their component parts. Thus, wine is nothing but a particular organization of chemicals.

AVA Winery in San Francisco claims that they can recreate any wine simply by analyzing its chemical constituents and combining the appropriate chemicals. According to their website if you combine the right acids, amino acids, sugar,  volatile organics, and ethanol you can create any wine you want. No messy grapes, expensive barrels, or time consuming fermentation. Just chemicals.

The owner’s holy grail is to recreate the 1973 Chateau Montelena Chardonnay that won the Judgment of Paris. However, they are currently taking orders for a replica 1992 Dom Perignon Champagne which they will sell you for $50. (The current market price of the real thing is $227) The wine has not yet been made so no one knows how successful this will be.

I think it cannot quite be true that they are making an exact replica of a 1992 Dom Perignon since they could not reverse engineer a wine that no longer exists. The current bottles of 1992 Dom have undergone years of bottle aging that have significantly changed their chemical structure. The best they can do is replicate what it tastes like today.

But I have some reservations that such a thing is possible. I doubt that today we know enough to determine which of the 1000 compounds in wine contributes to its flavor. Taste tests by independent somms have been thumbs down. In fact, their methods are no different from those used by the food industry to create the snack “foods” at your supermarket, none of which tastes like real food.

But there may be reasons to doubt such a thing is even theoretically possible. Some complex systems may have properties that are quite different from the properties of its component parts. They only emerge as the result of the interaction of the components. The crucial question is whether these so called “emergent properties” are fully predictable based on features of the component parts. If not, artificial “wine” will be at best an approximation. But if the features of complex systems are predictable and can therefore be engineered, artificial wine may be in your future.