Micro-oxygenation, or mox to its mates, is a controlled, periodically continuous addition of tiny amounts of oxygen to wine, usually red. Among other things, it’s argued to have the same effect as the aeration of wine during racking (taking wine off its sediment and putting in a clean container), and barrel maturation.

Forget the new world being leaders in technical winemaking innovation. Mox was devised in 1991 by Patrick Ducournau, of Domaine Mouréou/Chapelle Lenclos in Madiran, as a way of softening the tannins of his home grape variety, tannat, which has legendary tannins.

Benefits include the stabilisation of colour, the building up and softening of structure and the lessening of stinky, reductive notes

It’s now widely used across the winemaking globe, on tannic grape varieties. Mox and pinot noir are unlikely ever to be best buddies. Justin Knock, at the time one of the Foster’s Group winemakers said: “you use mox on tannic grape varieties, for softer styles of red wine to drink at an earlier age, and you can use it on your best wines to make them more complete.” He outlined the technique’s benefits as including the stabilisation of colour, the building up and softening of structure, the lessening of stinky, reductive notes during tank maturation, and the amelioration of ‘green characters’. He said it was used at Rosemount, Lindemans and Wynn’s.

The fundamental risk is oxidation. Peter Taylor, global winemaking development director at Foster’s Group said: “you need your quality control spot on because you’re doing something different. We taste and analyse more regularly than we would normally. We don’t know how much oxygen a wine needs during its development, so need to monitor carefully.”

The argument goes thus: racking saturates a wine with oxygen, which is then gradually absorbed and used by elements in the wine. A controlled amount is thought to be more predictable than racking, for example, somewhere between 60 and 80ml/litre/month before MLF (malolactic fermentation) and a very low rate after MLF, 1-2ml/litre/month, for up to six months, might be common. But it isn’t known how much oxygen a wine needs, so it’s still work in progress.

It can kill the fruit, over-oxidise the tannins and increase volatile acidity

Oxidation isn’t the only risk. Jacques Lurton, of international winemaking company J&F Lurton warns “Mox is a risky technique, it can kill the fruit, over-oxidise the tannins, increase volatile acidity by over three times if it’s not well managed and anticipated; [you may only see] the consequences six months later.”

He still uses it though, to stabilise colour, which is done between fermentation and MLF and can increase colour by up to 30% with apparently little effect on tannins. The oxygen fixes the colour to a tannin molecule. Otherwise the ‘unfixed’ colour molecules drop out.

Lurton said: “we don’t use mox during wine maturation after MLF, because it makes the wine too tight. It’s risky, you get a ‘tannic sensation’ and it stays in the wine forever.” He said they prefer to build structure in the vineyard with such techniques as water stress.

Temperature is something else to watch. If temperature is cold then reactions are slower and oxygen absorbs more easily which is an additional oxidation risk. It can take several days, even with close monitoring, to pick up the effects due to cold temperature lag time, by which time of course it could be too late. Ideal temperature range is thought to be 13 to 18°C.

Micro-oxygenation is not necessary

Not everyone is in favour of using micro-oxygenation. Nicholas Buck, director of Te Mata Estate in Hawke’s Bay, New Zealand prefers the low-tech approach, saying “Mox is not necessary. We’re very traditional, elevage en barrique with topping and racking, so our wines get plenty of oxygen over time. We achieve the same that mox tries to rush. With cellar temperature fluctuation, and two winters in barrel, we achieve lovely resolution of tannins with development of further flavours and aromas, and the wine is stable. Nice tannins, extracted well, can handle quite a lot of oxygen exposure. If you get the tannin right in the vineyard, and it’s right in the winemaking, you achieve long, elegant, even tannins.”

So mox helps improve the drinkability of young reds. And it is an addition of oxygen in a controlled fashion but we’re still experimenting to discover what the exact correct amounts should be, but we know they vary by grape variety and vintage.

Without tannins, all red wine would be a bit like Beaujolais nouveau, which makes tannin pretty important for wine structure, grip, texture, colour stability, quality and longevity.

Tannins are colourless until they bind with colour compounds.

Tannins are one of the principal polyphenols in wine and the natural tannins in grapes are all condensed tannins (or proanthocyanidins).  These are colourless molecules and they will bind with anthocyanins to form coloured compounds.  Jacques Lurton, of the famous Bordeaux wine family, explained “the colour is fixed to a tannin molecule that’s already in the wine [in the presence of oxygen]. [With no oxygen] the ‘free’ colour molecules drop out.”  Wine can also contain hydrolysable tannins extracted from oak barrels and chips, or from oenotannins added during winemaking. Oenotannins are extracts of oak, chestnut or grape seeds.  They’re regularly used as a fining agent, but they play their part in texture and colour stability too.

Tannins are located in berry skins, pips and to a lesser degree, stems. And some varieties such as cabernet sauvignon, nebbiolo and tannat are renowned for their high tannin content.

Managing tannins is fundamentally important for wine quality.

Managing the extraction of tannin from berries is one of the most important aspects of winemaking and has a significant impact on both the style and quality of red wines. For forward, fruity, supple wine styles, minimal tannin is wanted: carbonic maceration, or a pre-fermentation cold soak to extract colour may be the preferred option. 

Tannins, though, need alcohol to be extracted. And as lots of tannin tastes bitter and astringent, covering the tongue, teeth and gums in a gritty coating, managing the maceration of skins and liquid during and after fermentation is key, as it is at this time that phenolics especially tannins, colour and flavour compounds are extracted.

What emerges varies widely according to (a) the temperature of maceration, up to about 35°C, (b) the length of time over which maceration occurs, from a few days to a long month post-fermentation, and (c) the quantity and quality of agitation there is between solids and liquid part, for example the difference between a gentle punching down to a more vigorous roto-fermentation. 

Frank Mitolo’s, of Mitolo Wines in Australia, preferred tannin management is to “ferment cool, up to 25°C for purity of fruit flavours; don’t work the fermentation very hard, and use fine-grained oak.” 

So the permutations for tannin profile are vast. When it’s right it’s oh so seductively right, and when it’s wrong, boy, are our teeth gritted.

Even in recession-hit 2009, wine exports from Germany are  holding steady as the trend to fresh, refreshing, fruity wines continues to grow.  It looks as though we are finally beginning to realise Germany offers fresh, unoaked styles of wine, without the massively high alcohols that can give heat to the palate rather than flavour.

Slopes are important in Germany

Germany’s heritage of producing the greatest rieslings in the world is undoubted. They used to command the highest prices in Europe. Rieslings are again going from strength to strength in the UK, and this includes the traditional styles with some residual sweetness, which are popular with the under 35s, who seem to love trying these wines without the hang-ups that some of the over 35s still seem to have.  With light alcohol, these styles are ideal for lunchtime wines and for the popular gastropub culture. It seems the UK is almost the last to catch on to these light, refreshing, fruity styles of riesling.

But what few realise is that Germany also has a long heritage of producing red wines, although until recently, these were rarely found on any of the export markets.  But that looks set to change.  The last quarter of a century has seen some dynamic changes in the entire approach to red wine making style and quality.

PRESSING THE CHANGES

Just 30 years ago red grape varieties accounted for a little over 10% of the vineyard.   Rainer Lingenfelder of his eponymous estate in the Pfalz explained: “Red wine is not new, however there was a renaissance in red wine starting in mid 1980s. I was one of the growers who wanted to revive the red wine tradition in Germany.” As he’d already worked in Australia and at Grand Puy Lacoste in Bordeaux, he was in a good position to see the potential for red German wines.

In the early 1980s, the way to make red wines was to make them like white wine. Lingenfelder said: “German reds were nothing but a coloured white. Tannins were considered undesirable; malolactic fermentation was a no-no, so a typical pinot noir had considerable acidity, a very, very light colour, and the fruit was nicely ripe for spätlese (late harvest).  It would have been made in sweet style.  So German reds were  pale, with high acidity, some sweetness and no tannin.”  To international markets these would certainly not have been a desirable option.

A handful of forward-thinking producers knew they had to make red wine differently from white. As well as colour, Lingenfelder said they needed “structure, tannin, a completely different body. The key changes were lower yields in the vineyard, a classical fermentation on skins, and a reasonably long fermentation. Malolactic fermentation to reduce the fruity acids (malic), because malic acid collides with tannic acid on palate.  You can’t have both malic and tannic acids. Thirdly oak ageing.”

Lingenfelder said: “It was not the suitability of soil or lack of warmth. Pinot noir ripens properly in Baden, the Pfalz etc.  It was in our minds.  Having gone abroad, we could see from a different angle.  So the time was just ready.”

A quarter of a century later the evidence for good quality red wines is in the bag. Within Germany, some of them are fetching Burgundy 1er cru prices. Initially the demand was so high at home there was no need to export, and there probably still isn’t, but cracking export markets add prestige and profile to a producer, especially such a hard nut to crack as the UK market, where wines from all over the world are present in abundance.

Pfalz

RED GRAPE VARIETIES

While riesling has 20% of the vineyard plantings, red grape varieties are grown on more than a third of Germany’s vineyard area. Pinot noir, called spätburgunder, is the main one, with 11% of plantings, and there has been a big increase in plantings of dornfelder, more than doubling in the last five years, to account for 8% of total plantings. Even the likes of merlot and cabernet sauvignon have appeared since the new millennium, in very small quantities, and restricted to the warmer, more southerly regions such as Baden and the Pfalz.   

Pinot noir/spätburgunder: The best examples are from the Ahr, Rheingau, Pfalz, and Baden regions. Like riesling, it is a variety that is influenced by the terroir. Paul Fürst comments: “pinot noir is always a hand crafted wine. You have to work with the soil and the vine. Good pinot noir is always expensive, when you want minerality and elegance. We are always looking for low yields and thick skins on the bunch.”

Dornfelder: This is a vine crossing from the 1950s, and is a household name in Germany.  It is a deeply coloured variety with good levels of acidity and an aromatic, cherry fruit profile with smooth-textured tannins. The best examples can benefit from barrel ageing which give more grip and structure.  It’s easy to grow and easy to drink, generally having about 12%-12.5% alcohol.

The best reds are found in pockets all over the country, notably the Ahr, Pfalz and Baden. And Rudolf Fürst in Franken deserves special mention. Owner Paul Fürst said: “the western part of Franken is traditionally a red wine area, on red sandstone soil. The only interesting places for red wines are where you find strong soils, e.g. Ahr, Assmannshuasen in the Rheingau, parts of Pfalz and Baden. They make very different types of pinot noir. My type is strong, elegant, with wonderful colour and minerality, very long. 20 years ago we started with small barrels, and now have between 30-100% new oak.”

The small Ahr valley is the renowned red wine region of Germany, with 90% of its vineyard planted to red grapes.  It is one of the most northerly regions in Europe, further north than the Mosel Valley, and it has a special microclimate that allows red grapes to ripen.  Unusually, pinot noir here is planted in slate, which adds a mineral quality, fruitiness and elegance to the wines.

At the Mayer-Näkel estate in the Ahr, 80% of the winery’s production is red. Meike Näkel, who has spent time working in South Africa, explains: “we are very much in the north, but we have a very good microclimate. Our valley is narrow, the vineyards are very steep and south facing. In the narrow valley summer is hot compared to a region beside the valley. Our  soil is dark slate and stone, which warms up easily. The soils conserve heat and give it back to the vines at night-time.”

They export just 5% of production which Näkel says it is a new challenge. “My father started wine in 1982, at this time German red wine was not well known. Not many producers were making good red wine and this was the challenge for him. Now export is my new challenge. ”

Part of the challenge for quality-orientated producers of red wine is that most of the best are small players. They are often run by individual families who work hard in the vineyards and cellars to make good and exciting wines.  This of course means they only occasionally get abroad to promote their wines and build up a following. The onus is on wine connoisseurs sniffing out the best wines and spreading the word.