Taste, Wine, food, and combinations: Advances, and insights from science

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  • Post last modified:26 November 2023

These commentaries are based on Dr Gillman’s peer reviewed scientific papers, see Publications

Introduction

The pleasures of the table belong to all men and to all ages, and of all natures’ gifts remain the longest to console us for the passing of the rest

Jean Anthelme Brillat-Savarin (as are all subsequent quotes)

Wine and food may go well together, especially when cultural and psychological factors add to the experience: however, they do not generally enhance each-others taste, that is they are not strictly synergistic in a scientific sense — the sum is rarely greater than the parts.  That is to say, one chemical or tastant rarely enhances the ability of a receptor to perceive another tastant at a lower threshold.  However, the opposite is frequently true, in that many chemicals impair the ability to perceive different tastants by antagonising receptors (see below).

This ‘lack of synergism’ may be surprising when there is such a fuss, in some circles, about matching food and wine.  Note, however, I say not greatly: rather, they coexist, usually without having major influences on each other.  Common examples given of seemingly ‘synergistic’ combinations are gourmet-dinner-type things — like good sauterne and Roquefort.  

There are key elements of foods, or ‘tastants’, such as salt and glutamate, that do enhance sensory perception of flavours — a tastant is a molecule (or ion) that stimulates a specific taste receptor.  I am drawing a distinction here between specific tastants (like salt) and ‘foods’: that is a little pedantic and scientific, but, read on.

In our regular dinning the main serious issue is the opposite of ‘matching’; it is avoiding ‘clashing’, avoiding the relatively few clearly bad food and wine combinations.  Think of it like that and the basics are less complex.  This discussion concentrates on ‘taste’, but ‘weight’, texture, and temperature are also mentioned.  The concept of the weight of a dish, for instance, is exemplified by the advice that a hearty casserole needs a big strong (red) wine to match, notwithstanding subtleties like acid, sugar, and tannin.  A delicate hors d’oeuvre needs a light white, perhaps champagne, rather than a big buttery oaky chardonnay, or a strong red.

Our nervous system’s perceptual mechanisms need to perceive change and contrast to function best.  So, being exposed to the same taste (or smell) for longer, and at higher levels, dulls the perception of it.  Incidentally, the same principle applies to sight and hearing.  Long-term adaption in taste perception causes those who have a regular high-sugar intake to come to prefer sweeter wines.  Alternating compatible but contrasting flavours therefore tends to enhance perception, or at least better maintain its acuity.

Around 4000 flavour compounds have been described in foods, thus the possibilities for combinations and interactions are legion.

It is essential to note the role of the sense of smell, and it is commonly said that 90% of taste is smell.  Although that is an over-simplification of the sort that makes scientists wince, it is nevertheless the case that in usual circumstances smell plays a key role in the overall perception of taste.

Physical sensations like crunchiness (crisps, pork crackling) and fizziness (mineral water, sparkling wines) come into play, but will not be discussed at length.  

Smell and taste genetics: Inextricably linked

Smell and taste are in fact but a single composite sense, whose laboratory is the mouth and whose chimney the nose

Spence has recently discussed the question of the link between smell and taste for those who wish to read more deeply [1].  He points out that science still cannot precisely differentiate these two sensory modalities; assigning a precise percentage to the importance of smell is a delicate exercise of uncertain validity.

Smell (olfaction)

Buck and Axel received a Nobel Prize for their work on human olfaction in 2004.  An individual neuron expresses just one type of olfactory receptor (OR), these are ‘G-protein coupled receptors’ (GPCRs).  There are 350-400 specific OR receptors allowing us to perceive thousands of different odours.

There are an undetermined number of primary odours, probably around ten [2]: common descriptors include; camphor, woody, ethereal, musky, floral, non-citrus fruity, lemon, fruity sweet, popcorn (diacetyl), minty, pungent, chemical, and putrid.  Genetic variation in odour perception exist for a number of smells related to OR gene polymorphisms: among these are; isovaleric acid (cheesy, sweaty), androstenone (sweaty, urinous), beta-ionone (floral), cis-3-hexen-1-ol (green, grassy), and guaiacol (smoky).  The particular example of truffles and androstenone is discussed below.

The OR-2J3 gene variants for cis-3-hexen-1-ol sensitivity (green, grassy) may well influence liking for various foods — this is probably but one of many such examples that will emerge from ongoing research.

Taste

Animals feed; man eats. Only a man of wit knows how to eat

The molecular basis of our bitterness attribute was discovered in 2003 [3] and much of the variation in bitterness perception is due to three single nucleotide polymorphisms (SNPs) in TAS2R38, a bitter-taste receptor gene.  The gene sequences of more bitter taste receptors have now been found, and other functional SNPs identified in bitter taste receptors [4].

There are numerous and common genetic polymorphisms of these genes which account for individual variations in bitter taste perception: e.g. one confers exquisite sensitivity to propylthiouracil (PROP), it, or related compounds, are in red wines.  There are innumerable natural compounds activating human TAS2 receptors and these very probably determine some food preferences because individuals have different sensitivities to various of these bitter compounds — so, if your child does not like spinach, do not press them to eat it.

The perceived bitterness of ethanol differs, related to variation in TAS2Rs [5, 6], also those who are more sensitive to PROP may also experience increased taste, mouth-feel and aroma sensations from wine.

It wasn’t just the wine

A meal without wine is like a day without sunshine

For those less familiar with wine it can be helpful to think of food combinations and non-alcoholic drinks, like tea, coffee, and fruit juices (especially in combination with what you might have at breakfast).  Also, thinking about the different sauces that are usually served with dishes, including desserts, helps one to better appreciate how fat, acid, sugar, and tannin interact.  Food-food combinations, as well as food-wine combinations, are therefore helpful as examples of things that do, and do not, work.

Even accounting for the great variability of different peoples’ tastes (some of which are differences in taste receptors caused by genetic variations), there are combinations that almost anybody would agree are unpleasant, or at least negative.  For instance, a young tannic cabernet sauvignon combined with a green salad with vinaigrette dressing; a rich beef ragoût with a light acid herbaceous white wine.  It can be educative to actually try such combinations in order to appreciate what happens when one deliberately mis-matches things — try vinegar on your ice cream, or warm custard on a salad.  Deliberate mis-matching may be a useful and underused educational tool.

The temperature of foods (and wines) is another a key element when considering taste, especially for fats — cold fat tastes different to a warm or hot fat.

The physical (and psychological) state of the taster is also relevant.  A simple example of this would be the saliva in one’s mouth, which is high in protein, which binds with tannin.  If you were to drink black tea, or a typical red wine, after coming back from a run when you had a dry mouth, it would taste more tannic and unpleasant, compared with how it would taste if your mouth was moist with saliva.  That is why, at half-time, sportsmen have oranges (the acidity in citrus stimulates saliva flow), not black tea (tannin).

A related observation is that differences in the perception of astringency may relate to saliva flow rate and protein content.  Around 1 in 4 individuals are especially susceptible to oral astringency due to a reduced ability to replenish protein in their saliva, and these differences influence preferences.

The cheese and wine myth

A dessert without cheese is like a beautiful woman with no heart

There is another much talked-of and common combination that does not work well — most wines with most cheeses.  Wine and cheese parties* were not a connoisseur’s innovation.  Most good wines and good cheeses tend to clash rather than enhance — so, at the outset we meet a prominent myth of matching.  Therein lies another general principle, I emphasise ‘good wines and good cheeses’ because the higher the quality of the ingredients, the more skill and care is needed with matching, because the chance of spoiling distinctive and fine flavours is that much greater.

* This wine and cheese habit probably started in America in the early part of the 20th century and was adopted by the expanding English middle-class after the war, and eagerly seized-on by the wine-sales people. 

Five modalities of taste?

Tell me what you eat, and I will tell you what you are

To avoid the relatively few truly negative combinations is not complicated, one needs to focus on the recognised five modalities of taste — salt, sweet, sour, bitter and umami; although fat might be a sixth.

Salty and sour sensations rely on nerve signals mediated by ion channels, whereas bitter, sweet, and umami rely on G protein-coupled receptors (GPCR).  Astringency is closer to touch than taste and is mediated by the ‘touch’ receptors of the trigeminal nerve.  

The properties of fattiness and tannin are crucial.  Tannin is the ubiquitous plant compound that stimulates bitterness.  

Cultivating awareness of these tastes is a good exercise (motto, ‘think when you drink’) as it increases one’s enjoyment of food (and helps to prevent us from eating poisonous plants, as discussed below).  

It is noteworthy that some of these tastes combine in a wide range of ratios, whereas others need to attain a fine balance for optimal effect.

Five modalities: 1 Acidity (sourness)

Those persons who suffer from indigestion, or who become drunk, are utterly ignorant of the true principles of eating and drinking

Acidity sensations are caused by hydrogen ions (H+); acids, and acid salts. Examples of acids contained in food (typical Ph ~3-4) are; acetic acid, lactic acid, malic acid, citric acid, ascorbic acid (Vit C), tartaric acid, and benzoic acid.  Organic acids are all of similar Ph (sour), with citric being the sourest.

Acidity stimulates salivary flow, in humans it is the only potent stimulant of salivary flow, next is chewing, and least potent is sweetness: smell is a weak stimulus of salivary flow in humans.

Acidity clears and refreshes the taste-buds, especially of the unctuous but cloying effect of fat (and sugar): think vinegar, lemon juice, and food such as lemon with smoked salmon; and for wine, a (lighter more acid) champagne with salmon.  And, food-on-food, a sorbet, or sweet and sour sauce (acid balanced against sugar).

This immediately highlights an aspect of balancing and matching that is sometimes insufficiently considered: are we contemplating mixing together, or tasting one after the other?  There is a difference — prominently with the cleansing and refreshing effect of acid.  A draught of champagne, when your mouth is actually full of salmon with a hollandaise sauce, is quite different to using champagne to clear the palate ready for the next mouthful.  More about the order of tastes in due course: it is something that bears continuing thought, research, and consideration [7].

And wine-on-wine — the perceived sweetness of wine is much-affected by the level of acidity; so much so that wine-judges may underestimate the residual sugar level in wines with high acidity (think off-dry riesling).  As grapes become riper the balance shifts towards more sugar and less acid.  In warmer climates especially, this results in strong fruity-sweet wines with low acid, that can tend towards flabby and flat.  The relevance of the order in which tastes come has a simple example in the advice to have dry wine before sweet. It is an easy thing to demonstrate for yourself (try sauvignon blanc or riesling straight after Moscato or prosecco).

Acidity lessens perceived sweetness, and acidity cuts into fat.  A good awareness of acidity levels in food and wine is central: citrus and most less-ripe fruits (including tomatoes & grapes) are markedly acidic (Ph 3-4).  Some grape varieties and wine styles are naturally higher-acid, like riesling & Champagne (especially when less-ripe) and will be even more so when from a cooler growing region or season, or when picked early.

The Ph (acidity) of whites is commonly around 3-3.5 and reds around 3.5-4 — so whites have about 10 times more H+ ions in them (Ph is a Log scale).

Five modalities: 2 Sweetness

Sweet and fat are compatible in a wide range of ratios; sweet and acid need to be carefully balanced, as do sweet and salt (another easy one to illustrate for yourself with a range of test solutions in the kitchen).

Sweet wines with good acidity (e.g. Sauternes) are a match for rich fatty things like pâté or a rich fatty terrine. For food-food think Brandy butter (fat and sugar), and lemon curd, or Hollandaise sauce (fat and acid), and sorbet (acid and sugar).  If one starts a meal with foie grass and a Sauterne then a cleansing citrus sorbet between courses is a good move!  Otherwise, if the next course is served soon after, its impact will be lessened.  The order of tastes is everywhere.

Wines taste satisfactory when sweeter than the food, but the other way about just does not work.  Sweetness in wine acts as a foil to rich foods: however, trying to match chocolate with wine is even less productive than matching cheese with wine (texture and temperature come into play there).  It may be better to have each separately, they do not really enhance each other, usually they diminish each other.  A good dessert wine already has the acid, fruit character, and sweetness beautifully balanced and adding in anything else is likely to detract from it, rather than adding anything — so just enjoy it for itself, by itself.

Five modalities: 3 Umami and kokumi

The discovery of a new dish does more for the happiness of mankind than the discovery of a star

Escoffier, the legendary 19th-century French chef, considered that (his) veal stock had a special quality that he regarded as another ‘taste’: we now know he was recognizing umami, mediated by glutamate.  The history of glutamate is intricately entwinned with commercial food-flavouring and mass-production.  The observation that hydrolyzing vegetable protein increases both glutamate and palatability was noted by Liebig (1803-1873) and developed by Julius Maggi (his eponymous company still has an international presence marketing soups, sauces, and stock cubes).  Maggi aimed to make palatable nutritious food for the poor using hydrolyzed vegetable protein: he thought he had ‘invented’ meat extract and he made it into a rapidly successful industrial process (producing the first ‘stock-cubes’ along the way, before his death in 1912).  It was not until the turn of the 20th century that the Japanese chemist Ikeda formally described and named ‘umami’.  It was not until a century later, the turn of the millennium, that western scientists and cooks started to take much notice of this taste modality.  Perhaps an element of xenophobia plays a role in this still enduring suspicion about the reality of umami and the fear of MSG (mono-sodium-glutamate).  However, umami is now recognised by scientists as the fifth basic taste modality because glutamate meets the formal scientific criteria as a tastant.

Ikeda’s 1909 paper was not translated into the English language until 2002 when it was published in ‘Chemical Senses’, Lindemann’s introduction outlines the story [8]: the receptors were described starting just after the turn of the millennium [9-11].

Glutamate is the commonest amino acid in most protein sources, so it is hardly surprising carnivores evolved to recognize the umami taste, which is indicative of high-quality protein.

Nevertheless, there remains an irrational and exaggerated concern that MSG is harmful.  Most cookbooks hardly mentioned it until recently: e.g. McGee’s book on kitchen science (2004 edition) devotes barely one of its 800 pages to umami.  Public perception remains so negative that marketing promotion makes a point of stating ‘MSG free’ on labels.

A recent authoritative review [12] emphasized the following points: 

1) the human body is unable to discriminate between glutamate present in food and that added as seasoning (glutamate is glutamate is glutamate — as Gertrude Stein might have said)

2) glutamate cannot passively cross biological membranes

3) ingested glutamate is completely metabolized by gut cells and cannot elevate plasma glutamate

4) The maximum safe daily intake of 30mg/kg body weight/day is not even attainable when glutamate is consumed in the amounts naturally occurring in, or added to, foods (as MSG)

5) science using double-blind studies disproves the idea of individuals being ‘sensitive’

6) MSG is safe for humans of all ages, irrespective of ethnic origin

Glutamate is an unavoidable and natural component of all diets containing protein — it is totally safe.  Adequate protein intake is essential for the continuance of life.

As ever, ignorance, irrationality, and bogus claims are prominent in the food and diet space.

The umami taste is principally related to the amino acid (AA) glutamate (Glu). Of the 20 or so AAs, from which all proteins are constituted, Glu is present at higher concentrations than any other, in most protein sources (plant or animal), and in the human body.  In humans the entire amount needed is synthesized in the body from constituent AAs (it is thus designated as a ‘non-essential’ AA).  It is also a neurotransmitter in the human brain — however, ingested glutamate does not enter the brain, in fact it is broken down in the gut-wall before even entering the blood.  Even if injected intra-venously, it cannot get into the brain because it cannot cross the blood-brain-barrier.

At normal acidity levels found in foods (and physiologically) it exists not as glutamic acid, but as the glutamate anion: thus, when the flavour-enhancer mono-sodium glutamate (MSG) is added to cooking it dissociates into Na+ and glutamate¬ (just as salt dissociates into Na+ and Cl-) adding, only slightly, to Na+ in the diet.

The resulting taste is described as a meat-broth taste with an enduring, enveloping feeling on the tongue.

Umami flavour is enhanced by the purine ribonucleotides, inosine monophosphte (IMP) and guanosine monophosphate (GMP)) via allosteric modulation of the relevant receptors.

It now appears there are several receptors for umami activated by different mechanisms, as well as allosteric binding sites that may explain complementary interactions of umami-enhancing peptides [13].  Allosteric binding sites serve to increase or decrease the sensitivity of the associated receptor, thus substances that bind to them increase or decrease sensitivity to the substance that binds to that receptor.  It is thus the exception to the statement made above that few tastants enhance the perception of others.

Natural ingredients with potentially >1 g% (1 g/100 g) of glutamate are: soy sauce & miso, fish sauce, mushrooms, anchovies, tuna, and kelp sea-weeds (like Kombu and Nori), mature cheeses, and also tomatoes and tamarillos, which are related to tomatoes, and have higher Glu levels [14].  Drying of mushrooms and fish enhances Glu levels [15].

Human milk is one of the higher glutamate-containing mammalian milks — no wonder babies spit out tinned baby-food, they are trying to tell you something.

Many foods produced by microbial action and fermentation potentially have heightened glutamate levels: indeed, cheesemakers now try to engineer their starter cultures to minimize the break-down of glutamate by particular bacterial strains during maturation, since lower glutamate results in diminution of flavour.

Quite how the idea got into the literature that Parmesan cheese is unique in having high glutamate is a mystery which is probably explained by failure to check original references — glutamate levels steadily increase during all cheese maturation, so cheeses aged for a year or two, rather than a month or two, will have higher glutamate [16-20]: e.g. levels in mature cheddar are 1,000 mg+/kg [21].

The famous chef Massimo Bottura has a signature dish ‘Five ages of Parmigiano Reggiano’: note temperature and textures are key factors in that ‘flight’.  He says that the discovery that parmesan is a key umami ingredient in western cookery has enhanced his appreciation and understanding of the dish: ‘Five textures, five temperatures and five levels of umami’.

Kokumi 

Kokumi is another newer taste described as thickness, longevity, and mouthfeel [15, 22, 23].  Glutathione (GSH), and related peptides (chains of AAs), which alone are nearly tasteless, mediate this ‘taste’ and elicit kokumi sensations without altering the primary Glu taste.

Glutathione is formed when Glu and cysteine are combined via the enzyme gamma-glutamyl-cysteine synthetase (this is the rate-limiting step in glutathione synthesis), then glycine is added: thus, it is a tri-peptide (i.e. 3 AAs joined).

The similar sulfur-containing compounds in garlic and onion, such as alliin, S-propenyl-cysteine sulfoxide, and GSH, have no tastes themselves but they give rise to kokumi flavors in the umami solutions or soups.  The extracellular Ca2+-sensing receptor (CaSR) is a probable mediator of kokumi.  These interesting GPCRs respond to amino acids, Ca2+, Mg2+, and phosphate, and play a role in various physiological functions [24, 25].

Five modalities: 4 Salt

He who receives friends and pays no attention to the repast prepared for them, is not fit to have friends

This taste is stimulated by soluble salts, mainly sodium (table salt, which is NaCl), but also potassium, calcium, and magnesium salts.  The taste threshold level is 0.007–0.016% for salt (seawater is 3.6%, approximately 35 g/L of salt).  Therefore, only 4 ml of seawater in a liter of pure water is detectable.  The different taste of types of sea-salt relates largely to varying amounts of the minor constituents, Mg, Ca, and K salts (all three are essential dietary elements).  Note that Mg particularly is a powerful bitter tastant, variations in the concentration of which affect the taste of sea salt.

The concentration of iodide in sea water is ~50 µg/L.  The human dietary requirement is a daily intake of ~100 µg.

The physiological state of the body may be a factor in the perception of saltiness; someone who is salt deficient has an altered sensitivity to saltiness in food.  However, relatively little research has addressed this important question in humans, despite the clear evidence that this is so in animals — if a cow knows when to go to the salt-lick one might suppose the same innate survival capacity has not mysteriously vanished in apes and Homo Sapiens.  Indeed, from an evolutionary point of view that is most unlikely, because when we came down out of the trees and started to walk upright in the grasslands, in order to better spot the lions before they ate us, low blood pressure when standing upright was a problem for primitive man: adequate salt intake was therefore crucial, and that is linked to the loss of the uricase gene at that stage of our evolution — the resultant increased uric acid levels modulate the rennin-angiotensin system and raise BP (see other article).  Therefore, the genetic ability to taste and select appropriately salty foods is likely to have been under positive selection pressure during our early evolution.

Notwithstanding the equivocation on this issue in the medical literature, it is probable that if we need salt then we will show a preference for salty food.

Sweetness balances with salt (up to a point), e.g. Parma ham and melon, or ham and pineapple.  Salt also balances acid.  It clashes with tannin. 

Salt is an ancient preservative, whether it be in butter or cheese, or preserved fish and meat, or sauces like fish-sauce or Soy sauce.  All of these are high salt foods.  Soy sauce has about the highest concentration of salt of any food, typically around 60 g/L, but can be 150 g/L (labels usually refer to Na+, so x 2.5 to calculate salt content).  As with cheeses, the salt is essential in the production process and as a determinant of the ultimate quality and taste.  Since, in sensible eating, only ‘condiment’ quantities of soy sauce are used, the salt content is not a major issue when it is part of a normal diet.

Salt clashes with tannin; for example, especially avoid light young tannic reds with salty food.

An aside about salt and health

Salt is the chemical sodium chloride (WHO now recommend <2 g/day of sodium); note 2 g of sodium is equal to 5 g of salt (NaCl) — do not get muddled up when reading about this, some sources quote sodium, and some salt. 

In commenting about salt consumption, it is impossible to avoid a reminder that most of the dietary advice given by health professionals over the last 50 years has been either wrong, or significantly misleading — indeed, not an advance over what Granny used to say: ‘a little of what you like my dear’.  The current beat-up about salt falls into that category.  The evidence is that for the great majority of people salt intake must exceed ~15 g of salt per day before significant adverse health consequences eventuate [26].  A salt intake of 15 g/day is not going to be reached by those who eat sensibly: nevertheless, an awareness of one’s salt intake is relevant.  It is probable that only a minority of those with hypertension are ‘salt-sensitive’ [27, 28].  

Those who work in hot climates may need to take extra salt in order to prevent weakness and cramp.

The obsession with reducing the salt content of cheese in some quarters is misguided, both from the point of view of cheese quality, and of health.

Five modalities: 5 Bitterness and astringency

Tannins are prominent mediators of bitterness: they clash with salt, neither do they go well with acid, unless balanced carefully (think cold black tea with grapefruit juice).  In wines they need to be in fine balance with the other elements, within a narrow range.

Bitterness and astringency walk hand-in-hand, yet they are not the same.

Tannins make the mouth pucker — think strong cold black tea.  Cheap Assam tea, usually the major component of ‘English breakfast’ teabags (made from floor-sweepings, the trade-word is ‘dust’) would be a good example to taste in order to calibrate your ‘tannin-meter’.  If you dislike that taste then you are probably relatively tannin-sensitive, and you may be better off avoiding the higher-tannin red wines.  Indeed, in the evolutionary past such sensitivity had survival consequences because bitterness is a warning of poisonous properties in plants — so high tannin-levels trigger the grimace of disgust.

The same parts of the brain are activated during the experience of ‘bitter disgust’ and by seeing disgusted expressions in others, which thus effectively communicates a warning [29, 30].  Such responses to taste are genetically programmed because that has survival value: they are innately exhibited by human and other primate newborns.  Sweet things (smiles) are liked by herbivores and omnivores — obligate carnivores, like cats, cannot detect sweetness; cats do not smile: dogs are omnivores; they detect sweetness; they smile [30, 31].

Tannin chemistry is complex.  Tannins in red wine are present at levels of hundreds of milligrams/L, much greater concentrations than sugar or acid: potentially the power to overwhelm others tastants.

Bitterness tastes come from a great variety of bitter compounds that are prominent in many plants, therefore they are present in all vegetables, red wine, beer, tea, and chocolate; they activate the taste 2 receptor (TAS2R) family of bitter taste receptors — there are 25 sub-types, ‘tuned’ to different bitter compounds.  Bitterness is thus the most complex of our taste sensations.  Some common compounds that evoke bitterness are; quinine, caffeine, tannin, magnesium sulphate (Epsom salts), and potassium chloride.  Other TAS2 sub-types relate to our liking for grapefruit juice, and caffeine bitterness perception [32].

The evolutionary development of bitter taste receptor genes throughout the many animal taxa is fascinating: it indicates the ebb and flow of the battle plants have waged over hundreds of millions of years to discourage animals from eating them.  For a detail review see Behrens [33].

‘Astringency’ in red wine is a ‘tactile’ sensation involving dryness and tightening, and unlike other ‘taste’ sensations, which decrease in intensity on repeated exposure, astringency increases on repeated exposure. It appears to be mediated by, among other things, high concentrations of PROP-like compounds acting via trigeminal neuron tactile receptors [34-36].  This is an example of how a tastant can stimulate one set of receptors at a lower concentration, and different receptors at a higher concentration: all interactions between chemicals and organisms are crucially dependent on concentration (‘All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.’ Paracelsus).  

Different compounds activate different combinations of the ∼25 different TAS2 receptors, but tannins are prominent ‘natural’ agonists with high and specific potency toward a particular receptor sub-type of TAS2 [30, 37, 38]

The tannin level in a wine depends on the characteristics of the grape variety and the techniques the winemaker uses, especially how much contact the juice has with the stalks, skins, and pips.  Tannins can also be added, just like sugar or acid, although that may be regulated.

Generally, interactions between agonists and receptors are temporary and reversible, however, tannins react chemically with proteins, and that is irreversible, and they also react irreversibly to long-chain fatty acids (LCFAs) [39].

Cheese is a fat and protein amalgam and it reduces perceived tannic bitterness, especially of weak tannic Bordeaux-type wines — hence the old trade trope of ‘sell on cheese but buy on apple’, which goes back to the Romans.  Cheese does not ‘improve’ red wine (and cf. salt), it reduces the taste impact of over-aggressive tannin in poorly-balanced red wine, so making it taste no so much better, but less bad.  It will not make a good well-balanced wine taste better.

Try chewing a bit of fatty cold lamb, it is very cloying, and one can taste many things less well after it — without clearing one’s mouth and refreshing one’s taste-buds.  Most lamb cuts are fatty protein and therefore go well with a more tannic red, especially one with good acid levels (i.e. most cooler climate reds like cabernet, shiraz; but less-so if they are riper, examples from hot climates — and see below for low-tannin reds).  Again, the order of tasting is crucial, red after fatty lamb cleans and refreshes the palate, resetting taste receptors to appreciate the next mouthful and lessening the tendency to become inured to one flavour or characteristic [7, 40].

More modalities, fattiness?

Appreciation of fats has generally been considered to involve only textural and olfactory sensations, until recently.  That brings us to a word that needs to be ‘dealt with’ in this context: savory.  It derives from the Latin root ‘sapor’, meaning taste; a non-specific description that has remained with it ever since.  It has no commonly agreed or formal definition: perhaps the closest one can get is ‘tasty but not sweet’.  Perhaps it would be best reserved to describe the rich sensation of something with umami and fatty characters.

Chemo-reception of free fatty acids (FFA) probably exists in humans.  Long chain free-fatty-acids (LCFA) are definitely detected and preferred by rats and mice; healthy adult humans can specifically detect the presence of LCFA in the mouth.  That alone is not sufficient for science to define them as tastants.  For non-scientists it is probably useful to think of fattiness as a taste sensation and a feeling, even if the science defining it as a unique taste is not quite certain yet.

Temperature is important, especially in relation to fatty tastes — think of cheese that is served too cold (an all-to-common occurrence), or a roast shoulder of lamb vs cold lamb fat. Indeed, cheese is an example of a common food that is spoiled by being presented at the wrong temperature.

Temperature is important, especially in relation to fatty tastes — think of cheese that is served too cold (an all-to-common occurrence), or a roast shoulder of lamb vs cold lamb fat. Indeed, cheese is an example of a common food that is spoiled by being presented at the wrong temperature.

Protein

Protein needs to be in balance with both acid and tannin, and when fat levels are low (venison, kangaroo) that is a more delicate balancing act.  There is no clash with salt, sugar, or fat. 

Lean meat such as venison and Kangaroo does not suit too much tannin.  Traditional matching advice about wines and meats is influenced by the times when many cuts were fattier — nowadays many people go for leaner cuts and with less of the rich and fatty sauces, this influences what wine will be most suitable.  Lean meats do not go well with high tannin wines, a little tannin is good, but it is a more delicate balance vs. the protein than it would be with fattier meats.  It is rather like the effect of tannin on saliva (which has a high protein content) — the chemical binding of tannin-protein neutralizes the bitterness of tannin until all the protein is bound.  Beyond that point the bitterness becomes more prominent.  Mild bitterness can be stimulating, excessive bitterness trends towards unpleasant.

Genetics and taste

To invite a person to your house is to take charge of his happiness as long as he be beneath your roof

Science is only just beginning to unravel the details of genetic variants of human taste receptors and how these affect the perception of particular tastants.  The above text touches on one or two examples, but here are other examples to illustrate the sort of changes that have been demonstrated.

Truffle anosmia: Androstenone is a sex pheromone produced by pigs and is present as a principal odorant in truffles, which explains why pigs hunt them so avidly.  However, androstenone anosmia (the inability to smell it) occurs in ~30% of humans — that means paying thousands of dollars a kilo for them might be a waste of money!  Even among ‘smellers’ there is variation in the degree of perceived pleasantness.  The progress of scientific research on these matters reminds us that it is unwise to over-interpret some of this research which is a work in progress; however, it does seem that age, sex, prior exposure, and genetic factors all influence perception.  Although some adults are anosmic, most children are smellers, and anosmia is commoner in men than women: some individuals may learn to smell it on repeated exposure.  Those who smell it most intensely are more likely to describe it as ‘sweat’ or ‘urine’, as opposed to pleasant (musky, woody, sweet), and it has been shown that the odorant receptor OR7D4 gene influences both its smell intensity and pleasantness [41-43].

In summary: about one third of humans tested only smell it weakly, and one third strongly: for those who smell it most (9/9 on a 0-9 scale) 70% of those rated that smell as ‘sweat/urine’, rather than as pleasant.  Ability to smell it is significantly genetically influenced.

Coriander: the population is genetically divided in terms of whether they perceive it as herby and pleasant, or soapy and unpleasant [44].

Rotundone: this compound is responsible for the characteristic peppery aroma found in peppercorns and some wine varieties, especially Shiraz.  Approximately 1 in 5 individuals are unable to smell it, even at high concentrations, but a genetic basis for this remains to be elucidated.

Spices: Many spices contain compounds that activate Transient receptor potential cation channels TRP-V1 & -A1, & M, ion channels. 

Transient receptor potential melastatin (TRPM8) mediates coolness (menthol [45].

TRPA1 activators include: allyl isothiocyanates (mustard, horseradish, wasabi), Chilli, (capsaicin), organosulfur compounds from garlic and onion, tear gas.  They mediate heat and touch hypersensitivity, and neurogenic inflammation [46-49].

Mustard contains isothiocyanate and may attenuate the bitterness of tannin [50].

Oddities: Beer and wine (especially white) are very prone to develop an unpleasant sulfurous odor (cooked cabbage), termed ‘sun-struck flavour’, within a few minutes of exposure to sunlight, and more slowly under artificial light.  Its formation is due to 2-methyl-2-butene-1-thiol, or similar volatile sulfur compounds.  It happens in as little as 24 hours in coloured glass, and 3 hours in clear glass.

It is probable that the adverse effects of light on a variety of foodstuffs by several different mechanisms have until now been under-researched and underestimated — this includes the degradation of cooking oils, cheeses, and vegetables. 

Red wine and cheese: Damage control

To say that we should not change our drinks is a heresy; the tongue becomes saturated, and after the third glass yields but an obtuse sensation

I quote here from Bromberger et al. [51], a great article in World of Fine Wine:

Whatever the rationale, matching red wine to cheese is only ever an exercise in damage control … The fat and protein content of cheeses, as a percentage of the total mass, is entirely dependent upon the amount of residual moisture. Indeed, cheesemaking is perhaps best described as the removal of water from a milk gel.

One key problem is the clash between salt and tannin — most reds have high tannin and almost all cheese is high in salt, often as much as seawater (3.6%), and more.  The actual composition of different cheeses does not vary with respect to the ratio of the principle components (protein and fat), just by the amount of residual moisture: rich soft cheeses have (by weight) ~23% fat, hard Cheddar ~32% (less water); all have high-salt (1-6%, i.e. 10 g/kg up to 60 g/kg).  Typical butters are 0.5-1.5%.  For details of salt in UK supermarket cheeses see Hashem [52] and for an international perspective see Guinee, p 318 table 13.1 [53].

Research and rigorous taste-testing indicate that, for red wines especially, the tannin-salt clash means ‘matching’ is more to do with ‘damage control’ than with synergy or enhancement of flavours.

Let me marshal one or two vinous and gastronomic ‘big-guns’ on my side, in case you think I am talking nonsense; among those in agreement: Michael Broadbent MW (Christie auctioneer), Michel Roux, Jancis Robinson (her report on the Bromberger-Neil’s Yard tasting is a must-read), and many others: https://www.jancisrobinson.com/articles/dont-just-say-cheese-with-red-wine

Note that Jancis Robinson confesses that for years she had, like so many of us, unthinkingly ordered cheese to help with the left-over red(s).  Old habits die hard.

Ambrose Bierce might have defined it thus in his ‘Devils Dictionary’.  

Cheese-board: a minefield for wines where gourmet reputations lie in tatters.

Quality matured cheeses require a high salt content to preserve their flavour characteristics during aging (at least 3 months, and 3 years or more).  They are usually ~3.5% salt (i.e. 35 g/kg, the same as seawater).  Aging is what increases amines, including glutamate, which produces the umami taste.  Soft non-matured cheeses may be as low as ~1% salt, but some are 3% or more, similar to matured cheeses (the label should tell you, but it will be given as Na, not ‘salt’, so Na 200 mg/100 g is salt 5 g/kg).

Salt and tannin have a negative interaction, usually perceived as disagreeable, but salt and sweet works, if balanced: acid and lean protein is not a good match (try dry riesling with lean venison fillet).  Thus, the high salt (and fat) content of Roquefort cheese works with sweet Sauternes (which, like almost all white wines, has low tannin); texture and weight come into that equation too: and therein lies the clue as to why vintage port is not in fact a good match for cheese, because the more tannin the port has, and the more salt the cheese has, the worse is the match (try adding salt to tea).  The ‘classic’ match of port and Stilton is not logical, unless you have a cellar with very well-aged vintages whose tannins have mellowed (precipitated out) sufficiently: the salt-tannin clash is the dominant negative factor.  For those who do not have 30-year-old vintage port lying around, a good fruity sweetish ruby style, or an oldish, sweetish (lower tannin) tawny is a better match.  The younger vintage ports many people can access are high tannin — not a good match.

There is an obvious logical non sequitur in claiming Sauternes and Roquefort, but also vintage port and Stilton, make good matches — it just does not add up because the wines are quite different, but the two cheeses are the same in terms of fat, protein, and salt (Stilton is typically at least 2.5%, and makers have got into trouble trying to reduce it to <2%, as demanded by the deluded UK ‘salt-police’).

A fresh, non-matured cheese, like goat’s cheese (if low salt, i.e. ~1%, that is 1,000 mg per 100 g serving, or 10 g/kg), will make a tolerable match with a rich later-picked (and sweeter) red, especially if it is lower oak/tannin, like primitivo (aka zinfandel), Valpolicella Amarone — think jam on cheesecake. But a sweet white would be better, a modest St Croix du Mont, Montbazillac, or the like, for instance.  But note that ‘fresh’ goats cheese distributed through supermarket chains may be much higher salt content to maintain shelf-life, as high as 10% (i.e.100 g/kg).

A dry white will definitely not suit a low-salt cheese; the acid-protein mismatch is dominant there (remember, the Ph of whites is around 3-3.5, and reds around 4): but it does work tolerably with a salty cheese.  Conversely with red, the higher salt clashes with the high tannin level and also both oak and tannin will emphasise bitterness.  Therefore, if you have a low-salt fresh goat’s cheese a red with good fruitiness and as low tannin as possible is as good a compromise as is possible (damage control); whereas with a high salt goat’s cheese, a fruitier and sweeter white will work satisfactorily.  But synergy it is not.

That all adds up to indicating the best bet, if you’re not sure what’s coming on the cheese plater, is to have a rich buttery Chardonnay style wine, but not one that is strongly oaked.

If you are fixed on the idea of a red then that is where the good sommelier comes into play if you are dinning out; ask him to find such a sweeter low-tannin red and he will appreciate your knowledge and probably know how the different wines were handled by the winemaker (a lot of tannin manipulation is possible).  And do not forget a fruity semi-sweet rosé.

Full-bodied, high-umami sakes, for those interested, are a versatile match for cheeses.

Remember, the fat and protein content of cheeses, as a percentage of their weight, is entirely dependent upon the amount of residual moisture.  Indeed, a large part of cheesemaking is the removal of water from a milk gel.

Combinations to avoid

For unknown foods, the nose acts always as a sentinel and cries, ‘Who goes there?’

It has become evident that some of the ‘traditional’ rules and prohibitions relate to what we might now see as faults in winemaking, like the anaemic, under-strength, low-fruit, acidic red Bordeaux wines, of past, and even present, years — do not forget that the Bordelaise highjacked the ‘black’ wines of Cahors to fortify their thin wines, such that many were really undeclared mutli-region blends (I will not even mention Algeria): and will we ever know how many hundreds-of-millions of liters of sugar syrup were shipped-in just to get the wine up to minimum strength?  Historically, the integrity of French winemakers has been a rubbery concept.

Some characteristics of foods were more prominent in the past.  For instance, modern lettuce now has a lower level of bitter alkaloids; rocket, asparagus, and artichokes likewise have lessened some of the characteristics they had in Roman times, or 100 years ago.  This has occurred through selective breeding, often to improve appearance, fruiting/cropping duration and shelf-life (i.e. commercial imperatives), sometimes at the expense of flavour.

Red wine was said to produce unpleasant fishy metallic bitterness with a number of seafoods (especially scallops).  This was thought to be related to iodine, but recent research indicates it more likely relates to the amount of iron in red wine, which can be around 1-10 mg/L [54, 55].  Modern wines are less likely to have significant iron because of changes in winemaking equipment and technology.  Low tannin reds are therefore likely to be fine with fish dishes, but powerful reds are not matched well with delicately flavoured fish (‘weight’ again).

Various food-plants contain particular chemical compounds that interact with wine: for instance, various green and herbaceous plants, like cucumber and capsicum.  Artichokes contain the compound cynarin which, for most people, creates sweetness in wine where there is none (cynarin blocks sweet receptors, but when ‘washed off’ by water creates a rebound effect of extra sweetness).  Asparagus contains methyl mercaptan, an easily tasted thiol compound (with a terminal SH moiety), described as ‘cabbage’, ‘garlic’, ‘onion’ and ‘rubber’; it is regarded as a defect when found in wines above a certain low threshold.

Miscellany

He who receives friends and pays no attention to the repast prepared for them, is not fit to have friends

Carbonation of drinks increases perception of sourness (acidity) because CO2 dissolves readily and is rapidly converted to carbonic acid (and thus H+ ions by the enzyme carbonic anhydrase on the surface of sour taste receptors [56] — therefore champagne may taste just a little sweeter when it loses its bubbles.  Typical carbonated water has a Ph of <4, and dry whites like riesling and champagne can be nearer Ph 3.  The sensation of ‘fizziness’ is little to do with bubbles bursting on the tongue, the sensation is the same if you drink your champagne in a pressure chamber (which stops the bubbles bursting).  That was first recorded by Jacques Cousteau in 1963 in Conshelf II which was 10 m below the sea in a pressurized habitat called Starfish House.  In truly Gallic style this boasted comforts like champagne, which did not bubble, but it tasted the same.  Carbonic anhydrase inhibitor drugs like ‘diamox’ prevent the increase in H+ ions at the receptor surface and spoil the effect.

The order in which things are tasted matters: sodium lauryl sulphate (in most toothpaste) blocks sweet taste perception (the effect probably lasts less than an hour), so a sweet fruit eaten afterwards tastes sour, and gymnemic acid, in Gymnema sylvestre, also depresses perceived sweetness.  Water tastes sweet after eating globe artichoke (cynarin).  Miracle fruit antagonises the acid-sour receptors, thus making subsequent foods seem sweeter.  Mustard reduces bitterness perception, and thus the impact of tannin.   There is much research on bitterness-masking compounds to improve the taste of foods and to mask the taste of many medical drugs.  Some of these compounds are specific to particular bitter tastants.  Although these are examples that are not likely to be much encountered, they do the illustrate the possibilities that exist.  Many plants contain unrecognized compounds which may have similar actions to those described above: in fact, most plant chemicals that are stated to be characteristic of particular plants occur in many other plants, either unrecognized, or in lower concentrations, or it may simply be that no-one has actually measured them properly.  Many such measurements are either technically difficult, or unreliable, or both.

Addendum

Low(er) tannin red wines

Wine carries the pleasures of the palate to their highest degree 

Rosé

Discussions of wine matching sometimes omit mention of rosé wines which have a role to play, especially in warmer climates where lighter wines and lighter dishes are often desirable.  For many people who try to eat healthily, and if one has more white meat, fish, and vegetarian, then the matching of wines more often will involve lower-tannin wines.

Rosés can exhibit a useful range of subtle variations in tannin content from low to moderate, as well as a wide range of fruit characters.  Although some examples, like cheap champagnes, may have elevated levels of residual sugar to disguise their lesser quality, there are plenty of examples of excellent fruity ones, as well as many superb bone-dry examples.  Europeans tend to be a little parochial, and others less aware, about the number of different varietals used for rosé wines — not long ago I had ten different grape varieties represented as rosés in my cellar, not counting blends (e.g. cab/shiraz rosé).  Nebbiolo, grenache, and of course pinot noir, make especially good rosé wines, but also seek out the Cabernet examples, as well as Merlo, Malbec, Tempranillo, Shiraz, Sangiovese, and…  It will keep you busy.  Familiarizing oneself with grape varietal characteristics in their rosé from can also be helpful in learning how to focus on the particular fruit character of that variety, which is easier to do in a low-tannin wine like rosé.

For red wines tannin is influenced not only by the grape variety itself, but also viticultural practices, the season, the way it is handled by the winemaker, and whether it is matured in new or old (less tannic) oak.

Typical characteristics

It is worth remembering, as mentioned above, that white wine generally has a pH of around three, versus red at around four, which means that white wine has 10 times as many hydrogen ions (acidity) than red.  Also, tannin is present in wine at levels of hundreds of milligrams per litre in red wines, but a fraction of that in most white wines.  Sugar is usually less than 10 mg/L except in dessert wines where it can be as high as 200 mg/L or even more.

Pinot Noir

An international favourite with early summer red fruit flavours and earthy mushroom notes, it usually receives low oak-barrel exposure.

Barbera

This grape from north-western Italy (Piedmont) can produce excellent wines and has fresh cherry, liquorice, and brambly fruit characters. 

Dolcetto

Dolcetto, again from north-eastern Italy, is more of a café style wine, but pleasantly fruity and low tannin; great with a lunchtime al fresco cheese platter

Gamay (Beaujolais)

A low(er) tannin, depending on how it is handled, high acid red, with tart red and blueberry fruit, so good with oily, fatty, high salt dishes (saucisson, grilled salmon, light chicken dishes, salads, and cheeses.

Valpolicella

It is made from Corvina and Rondinella in north-eastern Italy, sour cherry, cinnamon.  Poor examples, of which there are many, tend to be rather ‘lollipoppy’. 

Grenache/Garnacha

Modern Australian styles can have lower alcohol, low/medium tannin with lowish acidity; works well with a range of dishes including game and lighter white meat dishes and some fish.  The red plum, cherry and raspberry characters also make it a match for less spicy Asian-style dishes.

Montepulciano

This variety is widely cultivated, especially in central Italy and may be related to Sangiovese: it can be a full-bodied wine with rich dark spicy fruit and with low tannins (depending on how it is handled).

All the above varieties tend to lower tannins by their nature, but how low still depends on how the winemaker handles them.

 

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Dr Ken Gillman