The Chablis protagonists were Fabien Moreau, sixth generation and son of Christian at Domaine Christian Moreau Père et Fils, representing the ‘oak’ corner, while another sixth generation vigneron, Guillaume Gicqueau-Michel of Domaine Louis Michel et Fils, represented the ‘non-oak’ corner.

In a region with a notoriously precarious climate, climate change was high on the agenda. Among other protection measures, smudge pots are still used in Chablis, albeit infrequently, to offset frost risk to young buds. The risk appears to be lessening. Gicqueau-Michel last used frost protection in the heatwave vintage of 2003 which had had frosts early on in the season. Even then they used it only for one night, adding there was no great addition to their carbon footprint when compared with potential fuel use by tractors.

Combined with an apparent lessening of frost-risk at the beginning of the growing season are advancing harvest dates. In the 1980s harvest began around October 1^st. In the 1990s that date had advanced to the third week of September, and in the 2000s, said George, “a couple of vintages started at the beginning of September”. Gicqueau-Michel added “something is changing over the last 10 years.  We have had to harvest quite early several times.”  This issue, he said, is to keep the level of acid freshness in Chablis, adding “maybe we’ll have to be careful with the amount of leaf-plucking in the future.”

Focusing in on the two recent vintages shows quite different characteristics. Moreau described the 2009 vintage as “a good example of perfect climate. Everything was normal in terms of the average for the past 20 years. For me it was too good, it was a challenge not to harvest too late and to keep a certain amount of freshness.” Gicqueau-Michel added “the wines are more fleshy, and will open quite quickly.”

Chablis vineyards

This freshness was easier to achieve in the more classic 2010, where the acidity was higher. Gicqueau-Michel described it as a “great vintage. The greater acidity makes it more [typically] Chablis. The wines have a nice balance and complexity.”

But the lower yields in 2010 gave Moreau a concentration of fruit that year. Consequently, he didn’t keep much lees in 2010.  He said the amount of lees he does keep is keenly vintage dependent, and he likes “to see how the lees look after alcoholic fermentation because sometimes they’re good, or not so good.” In 2010, he said “the yield was too strong in terms of concentration” so he didn’t keep a lot of lees.

On the contrary, it was in 2009 that Gicqueau-Michel cut the maturation time on lees “because [the vintage] was warm, and we wanted to avoid a heavy wine, and keep the freshness.”

And when he does keep the lees, there is no battonage. On which subject Moreau agreed, saying “in 2002 [when the new guise of the domaine started], I did lots of battonage, and the year after I stopped it.  It’s why we’re using oak, so we don’t need battonage.”

George said battonage generally is untypical in Chablis.

And generally, she estimated that only somewhere between 5 and 10% of total Chablis production goes into oak. And where it is used at all, it is usually on premier cru and grand cru wine.

On their Le Clos, for example, Moreau may use 40% oak, but less than 2% of the total blend is new oak, and, said Moreau “we prefer longer heat at not so high a temperature” for toasting the barrels because “we’re not looking for oak flavour, but for a slow oxidation. Oak adds tannin structure to the wine, and we don’t use it for Chablis or Petit Chablis.”

Gicqueau-Michel remains un-tempted by the oak argument, saying “I want to continue to explore terroir, with its lots of small changes, so we vinify as neutrally as possible, using tanks.” He added “when we work with stainless steel, we try to manipulate as little as possible. There is very little contact with oxygen, so our wines will need more time to open than some other Chablis producers.”

Regardless of whether Chablis has been vinified using oak or not, George said with age “it has the chameleon aptitude of making you think it’s been in barrel, when it hasn’t.” Moreau suggested that with bottle age “acidity gets rounder and softer” which may influence a taster’s perception, while Gicqueau-Michel suggested this trait may be “a character of terroir. The typical aromas of Chablis evolve in bottle to mushroom aromas, humus characters, sometime buttery, nutty” notes.

Tasting, in London, November 2011

Apart from one oxidised bottle (no notes), this tasting was a treat for the palate and the brain.

Domaine Louis Michel et Fils, Chablis 2010
Citrus, meal, smooth, with steel acacia. Persistent palate with fresh, citrus, linear flow.

Domaine Christian Moreau Père et Fils, Chablis 2010
Oatmeal and steel nose, with acacia and apple blossom, steely attack and lemon curd. Smooth, refined and with a big depth of flavour and long finish. Very nice indeed.

Domaine Louis Michel et Fils, Chablis Montée de Tonnerre 1^er Cru, 2009
Steely allspice nose, hint of ginger and nutmeg complexity. Very smooth with good density of fruit, and tightly focused. Linear and good.

Domaine Christian Moreau Père et Fils, Chablis Vaillon 1^er Cru 2009
Fresh lemon toast, lemon curd toast, round and with some almond-gras/weight. Youthful spices of toast and nutmeg. Richness and latent complexity here.

Domaine Louis Michel et Fils, Chablis Grand Cru Les Clos 2009
Smooth, citrus, steely, lemon zest and pith, with silky texture and rich density of primary fruit layered with steely, flinty minerals. Richness from razor focus, with flesh of ripeness. Good.

Domaine Christian Moreau Père et Fils, Chablis Les Clos Grand Cru 2009
Lemon toast, vanilla pods and nutmeg nose in elegant, discreet proportions. Smooth, with fine open-knit ‘grains’ and warm richness of youthful fruit flesh. Long finish.

Domaine Louis Michel et Fils, Chablis Les Clos Grand Cru 2007
Nose a little muted, fruit erring to preserved lemons, still with linear acidity. Seems to be sulking a bit, yet to open up. Hints of fresh-light-cream on the palate attack, pristine and steely smooth.

Domaine Christian Moreau Père et Fils, Les Clos 2007, Chablis Grand Cru
Creamy, lemon toast, quite richly spicy, almond, honeyed dry toast with hint of nutmeg and even cardamom. Long length in palate, and long finish. Warm and clearly toasty. And very smooth texture.

Domaine Louis Michel et Fils, Vaudésir 2004, Chablis Grand Cru
Steel magnolias with smooth texture. Heading towards medium-full bodied fatness in a an attractive way. Smooth and rounded, warming and very drinkable. Vg.

Domaine Louis Michel et Fils, Vaudésir 2003, Chablis Grand Cru
Fleshy melon and peachy ripeness. Smooth and succulent, mouth-filling and perhaps not so classic? Rich, round, and not quite rotund. Aromatically spicy.

Domaine Christian Moreau Père et Fils, Blanchot 2006, Chablis Grand Cru
Round and fleshy with warm cardamom and aromatic spice. Oak spiciness in a warm, gently enveloping sort of way. Lemon curd on toasty nose, hint of sweet fruit, leesy cream, rich and fat in a Chablis context, i.e. still fresh and linear. Smooth, silky, delicious now.

Domaine Christian Moreau Père et Fils, Blanchot 2004, Chablis Grand Cru
Rich, honeyed, some overt nuttiness and open knit character. Full bodied and lush, still with a nice linearity and steel core. Very nice indeed. À point for me. Long finish with rich depth of flavour.

Domaine de Vaudon/Joseph Drouhin, Chablis 1989
Toasted, rich nuttiness and creamy-fat texture with full complement of tertiary, developed aromas, toasty, dry honeyed, fat. Lovely drinking.

Domaine Servin, Montée de Tonnerre 1998, Chablis Premier Cru
No oak, yet honeyed and toasted, with great amount of freshness still, with steely notes and blossom notes intact. Length not huge but, good flavours on the palate, smooth, nutty, floral, silky texture. Good.

Domaine des Malandes, Montmains 1996, Chablis Premier Cru
No oak. Citrus, fresh, indeed quite tart, and erring towards out of balance for me.

Domaine François Raveneau, Forêt 1995, Chablis Premier Cru
10% new barrels every year. Aromatic spice and  nuts on the nose, still tightly and tensely structured. Rich, fat, fresh, linear and taut. Little real sign of age. Huge concentration, finesse, elegance and depth. Long. Vg.

Domaine Laroche, Les Vaillons 1987, Chablis Premier Cru
Smoky, dark, roasted nuts, almost tarry aromatics, big, fat, still with freshness. Full and nicely balanced.

Domaine Christian Moreau Père et Fils, Valmur 2003, Chablis Grand Cru
Aromatic, youthful nose and palate of honey and acacia. Virtually no signs of ageing here at all. Quite full and ‘rich’ without weight or sweetness. Faintest hint of fresh. Dense, still-perfumed with rounded acidity. Lovely.

Domaine Long-Depaquit/Albert Bichot, Moutonne 2002, Chablis Grand Cru
Pale gold colour. Fat-cream and smooth toasty nose, firm acid core. A big wine.

Domaine de Vaudon/Joseph Drouhin, Vaudésir 2000, Chablis Grand Cru
White-nutty nose, creamed cobnuts. Smooth, round, softer acidity than experience so far this morning. Aromatic spiciness, with rounded acid profile.

Domaine Louis Michel et Fils, Grenouilles 1996, Chablis Grand Cru
Sweet, leesy nose, fresh-honeyed cream, nutmeg and allspice notes on the palate. Full, round, rich, fat mid palate, and with typical fresh backbone, even now. A bit of a warm finish. Good.

Domaine René et Vincent Dauvissat, Les Clos 1995, Chablis Grand Cru
Tarry, toasty nose, fresh-creamed cobnuts, youthful and delicious. Fresh nuts, still floral, and so young. Fresh, pristine, medium bodied and deliciously proportioned. Long, linear, lovely.

Even when those little gods of wine, the yeast, have done their fermentation job, they still do good work on wine, adding flavour, aroma, body, structure texture, weight, complexity, even petillance (that’s a faint sparkle, not a petulant little wine), and both protein and tartrate stability.

It’s important to discuss the right lees. Wine should always be taken of the gross lees (from the French for heavy), which in wine terms are gross (from the English for gross).  It is only the fine lees that are potentially good for wine.  

sur lie means ‘on the lees’

Essentially lees comprise dead yeast cells, and maybe some bits of grape skin and pulp that settle to the bottom of the vat at the end of fermentation.

This technique of leaving wine on fine lees mostly applies to white wines, but increasingly reds too are left on the fine lees for several months. The classic white wine example is Muscadet ‘sur lie’, from the Loire valley in France.  ‘Sur lie’ means simply ‘on the lees’, So this style should have a bit more weight, substance and character than a straight Muscadet.

Lees ageing is taken to its apogee in traditional method bubblies, such as Champagne, Cava, Franciacorta from Italy and Cap Classique from South Africa. 

Yeast autolysis (auto-breakdown of yeast cells by their own enzymes), as it’s called when used with bubblies, confers rich flavours of biscuit, brioche, white nuts such as almonds and macadamias, toast, even marmite notes which add depth, breadth and savoury character to the wine. Flavour crudely depends on the length of time the wine is in contact with the lees. So a Cava that has had the minimum nine months on lees will taste more of the original fruit than vintage Champagne, with at least three years on lees.  Autolysis is also argued to give fineness and persistence to bubbles.  And some argue that a greater integration of bubbles occurs with longer lees ageing.

stirring the lees lessens the risk of reductive conditions

Stirring the lees (battonage) in the barrel or vat is done to increase the effects of lees contact. This obviously cannot be done with traditional method bubbly, although some producers practise the art of poignettage where bubbly bottles are shaken to mix the yeast cells into the wine again, for example Gosset Champagne and Recaredo Cava. Stirring also minimises the risk of reductive flavours (think stink bombs and rotten eggs) occurring, which can develop under a thick layer of yeast cells. But slightly reductive conditions are good to help preserve primary fruit character, so it is a delicate balance to get the best from fine lees.

Mannoproteins are released naturally during lees contact. It is these that create a creamy, silky smooth mouthfeel, and a richer texture to the body of the wine. They are also important for wine stability.

A good, if expensive, comparison would be to choose a non-vintage and a vintage Champagne from the same producer.

Light is well known to promote chemical changes in foodstuffs.

Brewers have know about the flavour impact of light on beer for many years.  It’s widely reported in the beer industry that beer goes ’skunky’ when it’s exposed to light, even just in the time it takes you to nurse your beer on a lazy summer’s afternoon. 

Beer off flavour in the presence of light was noted as long ago as 1875, which is why, until the marketeers got involved, pretty much all beer was bottled in dark glass, amber having been found to be the best at filtering out most of the harming wavelengths.  

For wines, it is much more of an issue for whites and rosés. In reds the high tannin content offers a protective veil, binding riboflavin (more below).  And the issue can pretty much be avoided by using amber bottles, but with the marketing of any product, many considerations are important, not least the packaging, and we are seeing an increasing number of packaging options including clear glass, in both the beer and wine aisles.

A photochemical reaction occurs in both beer and wine. The responsible light wavelengths are between 350-500 nm, but activity is noted to peak at 370 and 440 nm, so in the near-ultraviolet and part of the visible wavelengths. Amber bottles filter out 97-98% of these wavelengths, which is why they’re the best. Dark green glass filters out just 63% of these critical wavelengths, while white flint (clear) glass filters a meagre 10%, so it’s only when we put beer and wine into clear glass (either bottles for the shop or pints/wine glasses for the garden) that the light degradation issue arises.

Light penetrating the glass excites riboflavin (vitamin B2, present in beer in concentrations around 1mg/litre, and in wine at concentrations at 0.4mg/litre), which acts as a catalyst, cleaving the compounds responsible for the classic bitter flavours in beer.

In wine, riboflavin, found naturally in must, reacts with cysteine and methionine (amino acids). Wine naturally contains 1-4g/l of amino acids. This reaction forms hydrogen sulphide and mercaptans, notably 3-methyl-2-butene-1-thiol (MBT).  MBT is the skunky thiol (mercaptan), smelling pungently of leek, onion, cooked cabbage, wet wool, soy etc. It is highly flavour and aroma active, and humans can smell it at concentrations similar to TCA, namely about 4 ng/l. In pale beer concentrations as low as 1ng/l can make the beer unpalatable. 

Paul Hegarty, head of communications for Coors brewers, has 15 years technical experience for brewers where ’sunstruck’ was high on the agenda. He was prosaic about the issue for beer, saying ”light struck has a skunky character, and rubbery – the flavour of beer when you’re sitting in the garden on a sunny afternoon.  Experts might define it as a fault, but consumers might quite like it.  It reminds them of sunny holidays.”  

Dr Ellen Norman, head of  analytical development and Brewing Research International said: “Research has suggested that consumers do not agree on whether they view lightstruck as a negative flavour in beer – some actually prefer it. We have also seen studies where consumers are unable to pick up differences between a beer before and after the beer has sat in the light.”

However, hop cones can be extracted using supercritical CO2 (of late renowned in the wine industry for reducing TCA levels in cork granules). The MBT-forming compounds undergo another process to make them light-stable, enabling the resulting beer to be stored safely in clear glass.  It is thought the number of brands produced using these processed hop products is relatively low.

Wine’s propensity to reductive flavours

But wine never got that ’skunky’ aroma. Peter Godden, group manager of industry development and support, at AWRI, said: “the formation of lightstruck flavour is exacerbated by low oxygen in both beer and wine, where the wine already has a propensity to develop reductive characters, but the reasons for this are different for beer and wine, because the compounds thought to be responsible in beer do not exist in wine.  However, lees-aged sparkling wine may be an exception, containing more methionine, and other compounds, than other wines, and so may therefore be susceptible to formation of lightstruck flavour through a mechanism that is similar to that in beer.”

We know some grape varieties and wine styles are more susceptible to reductive characters than others. Not every wine reacts the same way.  It also depends on how the wine is made, and how many amino acids it contains. Given the right (or wrong) light conditions, mercaptans develop. Gerd Stepp, who was winemaker for Marks and Spencer at the time (now consulting to them), explained: “mercapans are relevant in winemaking.  A lot of the precursor in wine is hydrogen disulphide (H2S). H2S has a high threshold, but it can continue to mercaptans, and these have a low threshold [4 ng/l].  So tiny amounts of H2S, almost undetectable, [can go into the bottle] but once the bottle is closed, the wine can develop hints of mercaptan.”

In the case of lightstruck cysteine and methionine amino acids come from yeast autolysis, the time spent on lees. Thus it is not so common to find champagne in clear glass. For wine with low amino acid content, so without lees contact, the chance for wine  to get lightstruck is much smaller. But, Stepp added: “You taste it much more easily in aromatic or neutral white wine, onion flavours come through.  With red wines there is more air, oak, open rackings, so H2S is lower.”

Paolo Bisol of Ruggeri said: “Our rosé has been in clear glass since 1950, but pinot bianco and pinot nero are less sensitive.  It might be better in dark glass, but you can see the colour. However, it is important for prosecco to be in dark glass because prosecco is sensitive to light.  It is light, fresh, young and fruity.” 

Sparklers

Wines such as traditional method sparklers, with their long lees ageing and consequently high amino acid content are susceptible to light struck.  Jean-Baptiste Lécaillon, director of vineyards and wines, and chef de caves at Champagne Louis Roederer said: “amino-acids such as cysteine are very important in wine as they are responsible for aromatic structure of the wines. In the case of sparkling, a large part of the aromatic profile is due to autolysis of yeast proteins. During the autolysis, some enzymatic reactions separate the proteins into thousands of amino-acids that are aromatic and responsible for the “yeasty”, “nutty” characters.”

He offered a number of solutions.  “Our only focus is to protect the wine from UV. You can do it by using green bottles that filter 92% of the UV, which is enough to protect the wine during a reasonable sun exposure. A strong sun exposure would be bad for any compounds of the wine…. so it is to be avoided.  For Cristal we protect the clear bottles with coloured cellophane. This cellophane is specially designed to filter 98% of the UV, which means, if the bottles stay wrapped, it is better protected than a green bottle. This is why we add in all our cases of Cristal a leaflet which recommends keeping the cellophane until the last moment.”  Of course this doesn’t mean the retailer or consumer will keep the cellophane on. The bottle looks pretty stylish without the foil, even with a warning note.

Marks & Spencer

Marks & Spencer use no clear glass at all for their wine range.  Five or six years ago all the wines were moved to green or amber glass. Stepp said: “If wine is in a presentation box then it might be in clear glass e.g. champagne, but the box protects the wine.”

But it’s not always  easy to get the most protective colour of glass. Stepp said: “UVAG green [a type of bottle colour] has a higher UV protective quality, they use a different oxide for colouring. But it is limited by availability, so we have to see if we can find it on the local market, and if not we go with the normal green.” He said it costs too much to transport empty UVAG bottles to the country of bottling.

The M&S policy makes it difficult to draw attention to their rosé wines, which many other retailers and brand owners market in clear glass to draw attention to their attractive colour and mood suggestions.  The M&S technical team insist on green glass to protect the wine, and this outweighs any marketing considerations. To signify rosé to consumers, the bottles all have overtly pink labels and distinctive pink capsules of the same hue to illustrate the wine’s tint.

Stepp said: “Commercially and presentationally it is quite a challenge. The rosé wine colour is less visible, and the colour of rosé is one of the key features of selling a rosé. Green glass is less attractive.”

Clear glass coating

There has been some experimentation with coatings over clear glass which filter the UV and allow the presentational benefits of clear glass. Godden said: “In 2001 we conducted a trial using a clear plasticised coating for the outer surface of clear glass bottles. Its purpose was to block UV light from damaging wine. A chardonnay wine was packaged in coated bottles, and also in the same bottle without the coating. The bottles were then exposed to UV light (approximately 50 cm from the light source of approximately 360 nm) for 21 days.

“During sensory evaluation the wine in the coated bottles was rated higher for freshness and for fruit characters, and lower for a whole range of reductive descriptors (reduced sulphur, smoky, burnt rubber, bacon, burnt match, gunsmoke etc.). The results were highly statistically significant – the coating appeared to work extremely well.”

Stepp explained why M&S had not pursued this option.  “A UV protective coating can be applied once the bottle is finished.. The coating has to be completely transparent on clear glass, otherwise it defeats the purpose. But if the coating is 100% clear, its protection only goes to 400nm. So the 440nm peak was not covered.  And to get protection over 400nm, the protective coating becomes coloured.”

Greater UV protective capabilities give a cloudy quality to the film, which may explain a lack of progression with this technology. Stepp suggested this avenue may still be worth exploring if there is some kind of bottle coating that is an improvement on what’s currently avail in the industry. 

The in-store environment

In a store environment under some types of fluorescent lighting wine in clear glass can develop noticeable degradation flavours after just a few hours.  Stepp said: “Green glass protection is not 100%, so store lighting is also important, as is stock rotation.  It doesn’t take long for mercaptans to form.  Generally the degradation of quality on shelf in clear glass would be quite high. Rosé is slightly more unstable because colour can turn. We’ve done a lot of work in store lighting, we’ve done tests with filters on certain light. We are using lights now that are better. And this is also relevant for other products, chocolate sensitive to light. 

Howard Winn, who was quality manager for beers, wines and spirits at Sainsbury’s, said: “We have a few wines in flint glass, mainly the usual suspects, rosé, sweet Bordeaux. It is an ongoing project to move away from fluorescent lighting, reducing the lighting in the BWS [beers, wines and spirits] aisles and moving to lower energy lights positioned away from the fixtures.  Deeper steel shelves have also helped reduce the exposure of bottles to light.  Our lighter sherry styles have recently been moved to different glass which offers higher UV protection.  Similarly our rosé Champagne moved to green glass a couple of years ago.  It’s all about protecting the wine.

Lecaillon was optimistic about the trade’s level of knowledge: “there is the question of bottle shops and fridges, It is obvious that if the wine is under full light for a while, there is an important risk of light struck, but I believe the trade is aware of that problem and take all necessary measures to protect the wine.”

With all the right precautions, light struck need not be a big issue, but the creative tension between brand image and positioning, and technical precision, means the issue is still relevant.  Stepp offers yet another option, saying: “There is quite a bit of work from our side on the wine making.  If we did progress on clear glass with rosé we would want to make the wines in a way that they are less prone to mercaptans, for example, have less of the amino acids cysteine and methionine; have a slightly faster fermentation, focusing on fresh fruit flavours with less lees contact. Our experiments are ongoing.”