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Au revoir terroir? The science of what makes great wines tick.
10 May 2015 by Chris Simms
Magazine issue 3020. Subscribe and save
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A vineyard's unique traits makes a wine – but not as expected. From minerals to microbes, we uncover the forces at work behind the world’s favourite tipple
The truth behind the taste?
As people start to get the hang of it, she asks us to shout out the flavours we detect. Everyone
thinks they smell fruit. One woman says eucalyptus. Another tastes flint. Our oenological guide
agrees, telling us that the mineral, flinty characteristic is a distinctive taste of this Chablis. "It comes
from the limestone in the soil of the vineyard," she says.
This story of how the Chablis got its taste is an alluring one – and it's meant to be. For many winemakers, the key to keeping their share of the $200 billion wine market comes down to the idea that local geography, geology, climate and winemaking practices, together known as the terroir, give a unique flavour to their wine. Thus their land is the only place you can make it. This idea forms the basis of wine laws around the world – it's why champagne can come only from the Champagne region of France, for example.
But does the idea of terroir stand up to scrutiny? We have recently unearthed the roles of soil, water, temperature, microorganisms and human practices in a wine's taste, and the emerging picture sends a question bubbling to the surface. If you can discover what gives a great wine its je ne sais quoi, would it be possible to mimic it elsewhere, perhaps even from vines grown in your own garden?
The most common way of thinking about terroir is repeated by wine experts and normal folk alike as they sip their fine burgundy or supermarket plonk. "It is standard in wine descriptions to mention the geological nature of the soils, as though granite, limestone or whatever confers some special ingredient, unknown to science. Most vineyards claim their soils are unique and very special," says Alex Maltman, a geologist at Aberystwyth University, UK.
In recent years, "minerality" has become a buzzword for these supposed mineral-like tastes. But there's no known process by which minerals can make it from the soil to the grape and then into wine in high enough concentrations to be tasted. And even if they could, what would they taste of? "With the odd and fairly irrelevant exceptions like sodium chloride, by and large, minerals have no taste," says Maltman.
"The idea you can taste minerals from the soil is absolute rubbish," says Barry Smith of the University of London's School of Advanced Study, who specialises in the multisensory perception of flavour. But that doesn't render the word minerality meaningless. A drink's feel in the mouth could give you a perception of minerality, he says. Often wines are described as having a taste of wet stone or dry slate. "If you lick a slate, it has no flavour," Smith says, "but it does leave you with a dry feel." Tannins in wine can make your mouth feel dry, so it could be this sensation that sometimes brings slate to mind. You might also be detecting a hint of slate because you were expecting to taste it.
Au revoir, terroir?
So is that the terroir case closed? Not quite: it turns out that if you grow the same grapes in different places, the resulting wines differ chemically. Last year, Régis Gougeon of the University of Burgundy in Dijon, France, and his colleagues used mass spectrometry to look at Pinot Noir grapes and wine from plots just 2 kilometres apart in the Côte de Nuits region of Burgundy. They found that the array of fatty acids, cholesterols, flavonols, phenols and more in the grapes and wine from each vineyard showed distinct differences – a chemical representation of terroir.What's behind this variation? One obvious answer might be the choices of the winegrower.
 |
| Image: Itani/Millennium Images In the dimly lit cellar below a London wine shop, a man gives his glass a good sniff. His nose plunges too deep and, for a moment, resembles an inverted iceberg, bobbing in a Chardonnay sea. Then he snorts, and his laughter destroys the illusion. "That," says the woman leading the tasting, "is not how to nose your wine." |
This story of how the Chablis got its taste is an alluring one – and it's meant to be. For many winemakers, the key to keeping their share of the $200 billion wine market comes down to the idea that local geography, geology, climate and winemaking practices, together known as the terroir, give a unique flavour to their wine. Thus their land is the only place you can make it. This idea forms the basis of wine laws around the world – it's why champagne can come only from the Champagne region of France, for example.
But does the idea of terroir stand up to scrutiny? We have recently unearthed the roles of soil, water, temperature, microorganisms and human practices in a wine's taste, and the emerging picture sends a question bubbling to the surface. If you can discover what gives a great wine its je ne sais quoi, would it be possible to mimic it elsewhere, perhaps even from vines grown in your own garden?
The most common way of thinking about terroir is repeated by wine experts and normal folk alike as they sip their fine burgundy or supermarket plonk. "It is standard in wine descriptions to mention the geological nature of the soils, as though granite, limestone or whatever confers some special ingredient, unknown to science. Most vineyards claim their soils are unique and very special," says Alex Maltman, a geologist at Aberystwyth University, UK.
In recent years, "minerality" has become a buzzword for these supposed mineral-like tastes. But there's no known process by which minerals can make it from the soil to the grape and then into wine in high enough concentrations to be tasted. And even if they could, what would they taste of? "With the odd and fairly irrelevant exceptions like sodium chloride, by and large, minerals have no taste," says Maltman.
"The idea you can taste minerals from the soil is absolute rubbish," says Barry Smith of the University of London's School of Advanced Study, who specialises in the multisensory perception of flavour. But that doesn't render the word minerality meaningless. A drink's feel in the mouth could give you a perception of minerality, he says. Often wines are described as having a taste of wet stone or dry slate. "If you lick a slate, it has no flavour," Smith says, "but it does leave you with a dry feel." Tannins in wine can make your mouth feel dry, so it could be this sensation that sometimes brings slate to mind. You might also be detecting a hint of slate because you were expecting to taste it.
Au revoir, terroir?
So is that the terroir case closed? Not quite: it turns out that if you grow the same grapes in different places, the resulting wines differ chemically. Last year, Régis Gougeon of the University of Burgundy in Dijon, France, and his colleagues used mass spectrometry to look at Pinot Noir grapes and wine from plots just 2 kilometres apart in the Côte de Nuits region of Burgundy. They found that the array of fatty acids, cholesterols, flavonols, phenols and more in the grapes and wine from each vineyard showed distinct differences – a chemical representation of terroir.What's behind this variation? One obvious answer might be the choices of the winegrower.
Everything from the watering and pruning of vines, to choosing when to pick the grapes, which
yeasts to use for fermentation or which barrels to age a wine in will affect the final taste. But
Gougeon's two vineyards were run by the same person, so something else must be behind it.
Hints come from work by Rosa Lamuela-Raventós of the University of Barcelona and her colleagues. Comparing almost identical plots of red Grenache grapes in Spain, they have shown that wines coming from vines grown in richer soil have muted colours, fewer aromatic compounds known as phenols, and seem less likely to improve with age. That might go some way to explaining a belief common among winegrowers: to produce good wine, the vines must suffer.
Other factors also mean we shouldn't be so quick to dismiss the concept of terroir. Tiny organisms within the soil and elsewhere can also influence wine. It's well known, for example, that mycorrhizal fungi form symbiotic relationships with plant roots and help them get nutrients, says Greg Jones of Southern Oregon University in Ashland. And just as you have a microbiome of organisms that are crucial to your health, so too, it seems, does a vine, and these vary from place to place.
"If you grew a plant without any microbes, you wouldn't have any wine," says Jack Gilbert of the Argonne National Laboratory in Lemont, Illinois. "Bacteria and fungi influence the chemical composition of the grapes and the health of the vine."
Special reserve
The concept of microbial terroir in grapes was revealed in 2013 by Nickolas Bokulich at the University of California, Davis, and his colleagues. The group showed that the freshly pressed juice of the same types of grapes (they looked at Chardonnay, Zinfandel and Cabernet Sauvignon) from different regions of California have distinct microbial make-ups – and these change from year to year. Not only that, but each part of a vine hosts a different bacterial and fungal community.
Gilbert and his colleagues have now looked at the RNA of those bacteria for genes that a plant might find useful. They found that bacteria on the grapes, for example, have more genes involved in metabolism and chemical defence – perhaps against hungry insects – both of which could conceivably affect taste. The communities of bacteria living on the leaves, flowers and grapes have more in common with those in the soil than with each other, so Gilbert suspects that the plant is recruiting different microbes from the soil to help with specific jobs. And this reservoir of microbes varies with factors such as the pH of the soil, so it may vary between different plants and rows in a vineyard, let alone between vineyards and regions, says Gilbert.
Those microbes can be very influential. Many sweet wines like Sauternes or Tokaji can be made only once grapes have been attacked by the fungus Botrytis cinerea, also called noble rot. This fungus is also associated with a compound called geosmin that can give wine an earthy or musty flavour, as can some bacteria that live on grapes.
Of all the microorganisms, it is yeasts that probably have the biggest effect on taste. During fermentation, yeast turns the sugar from the grapes into alcohol, giving rise to the 400-plus compounds dictating the taste, smell and mouthfeel of a wine. The "flint" that my fellow wine taster perceived in her Chablis is one example. "If a fermenting wine is starved of oxygen, then the yeasts produce sulphur," says Smith. "Just a bit and you get a smell like a struck match – people think it is flinty."
Many winemakers use starter cultures of Saccharomyces cerevisiae – brewer's or baker's yeast – for fermentation to ensure a uniform taste. But in recent years, there has been a move towards using the many yeasts naturally present in vineyards to bring out different flavours – a further source of terroir. Some people even swear off pesticides to protect their yeasts. Work by Mathabatha Setati of the Institute for Wine Biotechnology at Stellenbosch University in South Africa and her colleagues shows that there may be something to this. They found more species of yeasts on grapes in vineyards run according to organic principles than in ones that use conventional pesticides and fertilisers.
Some species of yeast are known to contribute very distinct notes to a wine. A pungent, farmyard smell can be down to a yeast called Brettanomyces bruxellensis getting in at almost any point in the winemaking process. Most regard it as spoiling the wine, but some winemakers in Bordeaux and the Rhone consider it part of their wine's distinctive style.
Your own microbes can even play a part in what you taste. The bacteria in the saliva of people with obesity, for example, suppress the release of aroma compounds from wine. You too can be part of terroir.
Looking beyond microbes, climate plays a huge, locally varying part in the taste of wine. Last year, Gougeon and his colleagues showed just how powerful a variable it can be. As well as pinning down a chemical representation of terroir, they looked at how this signature changes from year to year. Interestingly, the collection of compounds in the wines from the two plots they studied were a closer match to each other in any single year than they were to wines from the same plot in a different year. In other words, the weather conditions in a particular year – the vintage – can trump other influences. These differences also increase over time. "The expression of terroir in the wine grows, or changes, in the bottle," says Gougeon.
What is it about the weather that might be so influential? Temperature, rainfall and sunlight are just some of the factors that interplay to affect the health of a plant and the pace at which grapes grow and ripen. By doing this, they alter the proportions of chemical compounds within the grapes, affecting what goes into the fermenting tank and thus what the yeasts will kick out. Broadly speaking, wines from cool climates tend to have a subtle, crisp taste and lower alcohol, while wines from hot climates are heavy and bold with more alcohol.
Hints come from work by Rosa Lamuela-Raventós of the University of Barcelona and her colleagues. Comparing almost identical plots of red Grenache grapes in Spain, they have shown that wines coming from vines grown in richer soil have muted colours, fewer aromatic compounds known as phenols, and seem less likely to improve with age. That might go some way to explaining a belief common among winegrowers: to produce good wine, the vines must suffer.
Other factors also mean we shouldn't be so quick to dismiss the concept of terroir. Tiny organisms within the soil and elsewhere can also influence wine. It's well known, for example, that mycorrhizal fungi form symbiotic relationships with plant roots and help them get nutrients, says Greg Jones of Southern Oregon University in Ashland. And just as you have a microbiome of organisms that are crucial to your health, so too, it seems, does a vine, and these vary from place to place.
"If you grew a plant without any microbes, you wouldn't have any wine," says Jack Gilbert of the Argonne National Laboratory in Lemont, Illinois. "Bacteria and fungi influence the chemical composition of the grapes and the health of the vine."
Special reserve
The concept of microbial terroir in grapes was revealed in 2013 by Nickolas Bokulich at the University of California, Davis, and his colleagues. The group showed that the freshly pressed juice of the same types of grapes (they looked at Chardonnay, Zinfandel and Cabernet Sauvignon) from different regions of California have distinct microbial make-ups – and these change from year to year. Not only that, but each part of a vine hosts a different bacterial and fungal community.
Gilbert and his colleagues have now looked at the RNA of those bacteria for genes that a plant might find useful. They found that bacteria on the grapes, for example, have more genes involved in metabolism and chemical defence – perhaps against hungry insects – both of which could conceivably affect taste. The communities of bacteria living on the leaves, flowers and grapes have more in common with those in the soil than with each other, so Gilbert suspects that the plant is recruiting different microbes from the soil to help with specific jobs. And this reservoir of microbes varies with factors such as the pH of the soil, so it may vary between different plants and rows in a vineyard, let alone between vineyards and regions, says Gilbert.
Those microbes can be very influential. Many sweet wines like Sauternes or Tokaji can be made only once grapes have been attacked by the fungus Botrytis cinerea, also called noble rot. This fungus is also associated with a compound called geosmin that can give wine an earthy or musty flavour, as can some bacteria that live on grapes.
Of all the microorganisms, it is yeasts that probably have the biggest effect on taste. During fermentation, yeast turns the sugar from the grapes into alcohol, giving rise to the 400-plus compounds dictating the taste, smell and mouthfeel of a wine. The "flint" that my fellow wine taster perceived in her Chablis is one example. "If a fermenting wine is starved of oxygen, then the yeasts produce sulphur," says Smith. "Just a bit and you get a smell like a struck match – people think it is flinty."
Many winemakers use starter cultures of Saccharomyces cerevisiae – brewer's or baker's yeast – for fermentation to ensure a uniform taste. But in recent years, there has been a move towards using the many yeasts naturally present in vineyards to bring out different flavours – a further source of terroir. Some people even swear off pesticides to protect their yeasts. Work by Mathabatha Setati of the Institute for Wine Biotechnology at Stellenbosch University in South Africa and her colleagues shows that there may be something to this. They found more species of yeasts on grapes in vineyards run according to organic principles than in ones that use conventional pesticides and fertilisers.
Some species of yeast are known to contribute very distinct notes to a wine. A pungent, farmyard smell can be down to a yeast called Brettanomyces bruxellensis getting in at almost any point in the winemaking process. Most regard it as spoiling the wine, but some winemakers in Bordeaux and the Rhone consider it part of their wine's distinctive style.
Your own microbes can even play a part in what you taste. The bacteria in the saliva of people with obesity, for example, suppress the release of aroma compounds from wine. You too can be part of terroir.
Looking beyond microbes, climate plays a huge, locally varying part in the taste of wine. Last year, Gougeon and his colleagues showed just how powerful a variable it can be. As well as pinning down a chemical representation of terroir, they looked at how this signature changes from year to year. Interestingly, the collection of compounds in the wines from the two plots they studied were a closer match to each other in any single year than they were to wines from the same plot in a different year. In other words, the weather conditions in a particular year – the vintage – can trump other influences. These differences also increase over time. "The expression of terroir in the wine grows, or changes, in the bottle," says Gougeon.
What is it about the weather that might be so influential? Temperature, rainfall and sunlight are just some of the factors that interplay to affect the health of a plant and the pace at which grapes grow and ripen. By doing this, they alter the proportions of chemical compounds within the grapes, affecting what goes into the fermenting tank and thus what the yeasts will kick out. Broadly speaking, wines from cool climates tend to have a subtle, crisp taste and lower alcohol, while wines from hot climates are heavy and bold with more alcohol.
The climate's influence has many viticulturists uneasy about the future. Wine production typically
happens in areas where the growing season's average temperature is between 12 and 22 °C. Over
the next few decades, climate change will affect temperature and rainfall across much of the world,
conceivably altering which regions are most suitable for growing certain grape varieties. "Can Pinot
Noir perform in warm climates?" asks Jones. "Probably not. It is grown at the limits in Oregon,
Washington, Tasmania and New Zealand. These areas could lose that ability."
Other big names could also be hit. "Champagne is magical because it is cool in the region," says Jones. "Warmer weather would make it more difficult to create that distinctive taste there." Microbes could help, says Gilbert. Finding the right bacterial helpers could increase the resistance of plants to a changing climate. Or growers could swap to grape varieties better suited to the new conditions.
How Merlot can you go?
What we've covered so far can't explain all the interesting flavours in wine, though. It has long been wondered, for example, why some wines have a hint of eucalyptus. In 2013, the Australian Wine Research Institute declared it was down to eucalyptus leaves being picked up with the gathered grapes and releasing the odorous compound eucalyptol when crushed.
And a bitter, herb-like smell and taste, sometimes described as being like green peppers, can be caused by ladybirds – and the methoxypyrazines they release – getting bundled in with the harvest. The taste of smoke can even piggyback into wine when the waxy skins of grapes catch particles from the smoke of forest fires, says Jones.
But back to the big question. Now that we can separate out some of the taste influences in a wine, could we copy a 1998 Château Margaux, with its notes of berries, smoke, green pepper and earthiness? Do you just need Cabernet Sauvignon vines, some not-too-warm weather, a nearby fire, a handful of ladybirds and a sprinkling of fungus?
Rivalling great wines can certainly be done, says Maltman, as is shown by the success of many New World wines. But to mimic one exactly, you would have to know all the variables – and some might be hard to identify. "Lots of wine companies are interested in protecting their own flavours," Gilbert says. "If you uncover the secret that makes their microbiome and wine so awesome, maybe they're not going to be very happy."
It's hard to argue that replicating your favourite Bordeaux would be easy. But there's enough information out there to give it a good go, and all winemakers have to start somewhere. Perhaps it's time to look for a patch of ground and do some experimenting. And then... que Syrah Syrah.
This article appeared in print under the headline "Grape expectations"
Read more: "5 weird tastes that can sneak into your wine"
Other big names could also be hit. "Champagne is magical because it is cool in the region," says Jones. "Warmer weather would make it more difficult to create that distinctive taste there." Microbes could help, says Gilbert. Finding the right bacterial helpers could increase the resistance of plants to a changing climate. Or growers could swap to grape varieties better suited to the new conditions.
How Merlot can you go?
What we've covered so far can't explain all the interesting flavours in wine, though. It has long been wondered, for example, why some wines have a hint of eucalyptus. In 2013, the Australian Wine Research Institute declared it was down to eucalyptus leaves being picked up with the gathered grapes and releasing the odorous compound eucalyptol when crushed.
And a bitter, herb-like smell and taste, sometimes described as being like green peppers, can be caused by ladybirds – and the methoxypyrazines they release – getting bundled in with the harvest. The taste of smoke can even piggyback into wine when the waxy skins of grapes catch particles from the smoke of forest fires, says Jones.
But back to the big question. Now that we can separate out some of the taste influences in a wine, could we copy a 1998 Château Margaux, with its notes of berries, smoke, green pepper and earthiness? Do you just need Cabernet Sauvignon vines, some not-too-warm weather, a nearby fire, a handful of ladybirds and a sprinkling of fungus?
Rivalling great wines can certainly be done, says Maltman, as is shown by the success of many New World wines. But to mimic one exactly, you would have to know all the variables – and some might be hard to identify. "Lots of wine companies are interested in protecting their own flavours," Gilbert says. "If you uncover the secret that makes their microbiome and wine so awesome, maybe they're not going to be very happy."
It's hard to argue that replicating your favourite Bordeaux would be easy. But there's enough information out there to give it a good go, and all winemakers have to start somewhere. Perhaps it's time to look for a patch of ground and do some experimenting. And then... que Syrah Syrah.
This article appeared in print under the headline "Grape expectations"
Read more: "5 weird tastes that can sneak into your wine"
The weird things in your wine
 |
| Image: Jean-Luc Chapin/Agence VU/Camera Press |
Some of the tastes in what you sip can come from unusual sources
Ladybirds
Taste/scent: Green peppers, bitter herbs
Ladybirds
Taste/scent: Green peppers, bitter herbs
Insects are accidentally crushed with the grapes, releasing methoxypyrazines. In 2001,
this caused Canadian winemakers to dump 1 million litres of wine
Eucalyptus
Taste/scent: Eucalyptus, spicy and cooling Cause: Eucalyptol
If eucalyptus leaves get in with the grapes, they release eucalyptol when crushed. Some 40 per cent of Australian red wines contain detectable eucalyptol
Noble rot
Taste/scent: Intense sweetness, honey, apricots Cause: Botrytis cinerea
This fungus dries out the grapes, making them sweeter. Tokaji wine from Hungary, for example, gets its sweetness this way
Brett yeast
Taste/scent: Rancid barnyard smell Cause: Brettanomyces bruxellensis
This yeast can strike at any stage of the winemaking process. Some wineries, such as Château Musar in Lebanon, embrace its qualities
Smoke
Taste/scent: Smoke, wet ashtray Cause: Guaiacol
Waxy skins of grapes catch smoke particles, which contain guaiacol. After forest fires in 2008, much of the Pinot Noir from California's Anderson Valley tasted smoky
Harvesting damage
Taste/scent: Cat urine, boxwood, grapefruit, passion fruit Cause: Thiols
Some of the signature tastes of Sauvignon Blanc are accentuated in Marlborough in New Zealand. Higher levels of thiols in grape juice seem to be linked to mechanical harvesting there
this caused Canadian winemakers to dump 1 million litres of wine
Eucalyptus
Taste/scent: Eucalyptus, spicy and cooling Cause: Eucalyptol
If eucalyptus leaves get in with the grapes, they release eucalyptol when crushed. Some 40 per cent of Australian red wines contain detectable eucalyptol
Noble rot
Taste/scent: Intense sweetness, honey, apricots Cause: Botrytis cinerea
This fungus dries out the grapes, making them sweeter. Tokaji wine from Hungary, for example, gets its sweetness this way
Brett yeast
Taste/scent: Rancid barnyard smell Cause: Brettanomyces bruxellensis
This yeast can strike at any stage of the winemaking process. Some wineries, such as Château Musar in Lebanon, embrace its qualities
Smoke
Taste/scent: Smoke, wet ashtray Cause: Guaiacol
Waxy skins of grapes catch smoke particles, which contain guaiacol. After forest fires in 2008, much of the Pinot Noir from California's Anderson Valley tasted smoky
Harvesting damage
Taste/scent: Cat urine, boxwood, grapefruit, passion fruit Cause: Thiols
Some of the signature tastes of Sauvignon Blanc are accentuated in Marlborough in New Zealand. Higher levels of thiols in grape juice seem to be linked to mechanical harvesting there
Port Fairy Gourmet Weekend
Saturday 4 July 2015
Follow the Great Ocean Road to Port Fairy this winter to
discover a whole new world of gourmet produce and wine, as local producers team
up with one of regional Victoria's finest chefs for a lunch to remember.
Headlining this year's Port Fairy Winter Weekends
Festival, talented chef Matt Dempsey of 2 Chef's Hat-awarded Gladioli will team up with
passionate producers from Gourmet Port Fairy to create
a truly unique dining experience in the beautiful seaside village of Port
Fairy.
Matt's specially designed, 6-course lunch menu will showcase
the very best of Port Fairy's regional produce - think crayfish, abalone,
Skipton eel and local buffalo cheeses - with wines on offer from local
producers Basalt, Napa
Merri, Suffoir and more.
In the first event of its kind for the region, producers
from Gourmet Port
Fairy will swing open their farm gates to share with diners the many
gourmet delights of the fertile Port Fairy region. And in the hands
of one of Victoria's top chefs, you can count on the results being nothing
short of delicious.
So book now for your chance to be a part of this memorable
event where you and your friends will enjoy exquisite cuisine and fine wines
while embracing the cosy coastal charms of winter in Port Fairy. We look
forward to welcoming you!
Tickets $95 per person
* TICKET PRICE INCLUDES 6-COURSE LUNCH (DRINKS NOT
INCLUDED).
Tickets at Eventbrite.com or Port Fairy Visitor Information
Centre.
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