Like Marmite, we might have to agree to disagree when it comes to our own tolerance for wine faults. Either way, love them or hate them, it’s useful to know more about the ‘flaws’ you may encounter, says Natasha Hughes MW

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Back in the early 1990s, an awful lot of column inches were devoted to discussing the tiny mole situated above supermodel Cindy Crawford’s lip. Many believed that this tiny flaw elevated Crawford beyond mere prettiness and into the realm of the truly striking. As it is with supermodels, so it is with wine.

Over the course of the past couple of decades, thanks in large part to a growing awareness of the science required for precision viticulture and vinification, squeaky-clean wines are now produced on a consistent basis. But while technical perfection has become the new norm, a growing number of wine lovers have come to believe that these wines are utterly soulless.

Flawlessness is dismissed in favour of wines this group might describe as having character – but which others believe to be actively faulty. Tolerance levels are dictated, in part, by individual sensitivity to particular molecules, but in some cases ideological factors have a part to play as well. (The battle is at its peak when the words ‘natural wine’ are invoked.) It all rather begs the question of where you draw your own personal line between fault, flaw and quirk of personality.

Whatever position you take on the issue, there is a widespread acknowledgement that there are four main ‘flaws’ that still occur with a fair degree of regularity and which some wine lovers believe have a contribution to make in terms of increasing a wine’s complexity.

Natasha Hughes MW is a freelance wine and food writer and consultant

Written by Natasha Hughes MW

Wine faults: Oxidation

The relationship between oxygen and wine is an ambivalent one. The gentle introduction of oxygen to a wine during the maturation process – through the microscopic pores in a wooden barrel, for instance, or via the technique of micro-oxygenation – can help to lend a wine mid-palate weight and soften tannins.

Too much oxygen, though, results in oxidation. Affected wines are easy to spot: their colour is less vibrant (often with a brownish tinge) than you might expect given their age. One sniff or sip will confirm the diagnosis: there’s little freshness or bright fruit, and the finish is often marked by a bitter, drying character.

Oxygen can attack wines at any stage during their fermentation, maturation and storage (especially if the cork doesn’t provide an airtight seal). And yet not all oxidation is the result of a mistake. Many fortified wines – tawny Ports, palo cortado, amontillado and oloroso Sherries, Rutherglen Muscats and Topaques from Australia and the traditional sweet wines of Banyuls and Maury among them – rely on oxygen to create their hallmark flavour profiles. Madeira is another oxidised style of wine, though the term maderisation (which implies heating as well as exposure to oxygen) is more precise, albeit a little pedantic.

Some table wines, too, have traditionally had a whiff (or more) of oxygen about them (although not to the same extent as the overtly oxidised fortified wines). You’re most likely to find these wines in Old World regions where custom dictates that the wines spend prolonged periods in oak, often without the benefit of regular topping up, which helps keep oxygen at bay. These wines bear many oxidative characteristics – notes of nuts, dried fruits, beeswax and honey, for instance, as well as more obviously sherried (aldehydic) undertones. Happy hunting grounds – if you like this style – include Rioja (both whites and reds), Jura, Chenin Blancs from the Loire, Italy (particularly Piedmont and Montalcino) and the southern Rhône.

Wine faults: Reduction

While certain grapes – Grenache, in particular – are predisposed towards oxidation, other varieties head in the opposite direction, towards reduction. According to a strict chemical definition, reduction is a process that involves the loss of electrons, but in the context of wine the use of the term suggests the presence of volatile sulphur compounds.

Grapes that are particularly prone to reduction include Syrah and Sauvignon Blanc, especially when wines made from these grapes are vinified or stored in ways that preclude exposure to oxygen. (Screwcaps have a particularly strong reductive influence on wines unless steps are taken at bottling to adjust conditions accordingly.) Wines that have had prolonged lees contact during the course of their maturation often acquire reductive characteristics as the dead yeasts have a potent antioxidative effect.

At their most extreme, reductive characters can take the form of off-putting aromas such as rotten eggs or boiled cabbage, but a bit of gentle reduction can add complexity. The struck match character associated with some barrel-fermented Chardonnays or Semillon-Sauvignon blends is a reductive one, as are the smoky/gunflint aromas of many Sauvignon Blancs. Indeed, some characters often described as being ‘mineral’ are, in fact, reductive notes.

Californian winemaker Jamie Kutch believes that a small amount of reduction can benefit barrel-aged whites (particularly Chardonnays) enormously. ‘In modest amounts, it makes my senses come alive,’ he says. ‘If done correctly, it can create a wine whose complexity exceeds any wine without it. Drinking such a wine can be an outright religious experience!’

Not everyone is a fan, though. Philippe Dulong, consultant winemaker for Chateau Brown, actively takes steps to avoid reduction in his wines. ‘That reductive thiol character masks a wine’s fruit,’ he explains, ‘and I do everything I can to ensure that my wines are all about purity of fruit.’

If, like Dulong, you’re not keen on reduction, you might like to know that reductive wines can often be rescued by exposing them to air in a decanter. Dropping a copper coin into a glass of reductive wine and swirling it about often improves matters, too – not to mention that looks quite impressive, in a nerdy kind of way.

Wine faults: Brettanomyces

‘Great Burgundy,’ Anthony Hanson MW wrote in the 1982 edition of Burgundy, ‘smells of shit. Not always, of course, but frequently there is a smell of decaying matter, vegetable or animal, about them.’ While Pinot Noir rarely smells of faecal matter these days, thankfully, it is entirely possible that at least a part of the aromatic profile that Hanson was referring to was derived from the presence of brettanomyces.

Brettanomyces (or brett, as it’s often known) is a rogue yeast which thrives in wines with low levels of acidity. Wines are particularly vulnerable to brett when the main yeast, Saccharomyces cerevisiae, has died off before fermentation has completely finished, but brett can develop during maturation too – especially when the sulphur dioxide has been used sparingly.

Once brett has established itself in a wine, it produces a cocktail of chemicals that are responsible for its characteristic aromas. Foremost among these are 4-ethylphenol (barnyards, sticking plasters), 4-ethylguiacol (cloves, smoky bacon) and isovaleric acid (sweaty saddles). At high levels, these compounds not only mask a wine’s fruit, they can also leave its finish feeling hard and dry.

Many argue that the presence of a trace of brett can create additional layers of complexity, particularly when the emphasis is on the spicy, smoky bacon end of brett’s aromatic spectrum. ‘As long as brettanomyces is not overly obvious, I think it can add complexity and interest,’ says Steve Webber, the winemaker for De Bortoli in Australia. ‘Personally, I like it in savoury, rustic red wines.’ Generally speaking, though, the presence of brett is less acceptable in delicate Pinot Noir-based wines than it might once have been.

Wine faults: Volatile acidity

Volatile acidity (or VA) is, as the name suggests, composed of those acids within a wine that can be smelled, as opposed that can be detected on the palate. The major culprits are acetic acid (which smells of vinegar) and its associated ester, ethyl acetate (an odour reminiscent of nail polish); the balance of these compounds is individual to each batch of affected wine. Like brettanomyces, the bacteria that cause volatile acidity thrive in high-sugar, low-acid environments.

Although the presence of high amounts of VA is considered undesirable, in some cases a touch of volatility is no bad thing – particularly when it comes to botrytised wines. ‘The best Sauternes are full of volatility,’ says Jan Konetzki, head sommelier at Restaurant Gordon Ramsay. ‘It adds a savoury character that helps balance the wine. Without it, sweet wines usually lack complexity.’

Volatility also has its place in the aromatic profile of certain red wines, particularly those that have spent prolonged time in barrel. This may be why VA is often (and increasingly erroneously) associated with Italian reds, particularly traditional styles of Amarone and Barolo.

VA is not restricted to Italy, of course: Chateau Musar, Lebanon’s most famous red, tends towards volatility, as do some Châteauneufs-du-Pâpe. Even that most delicate of grapes, Pinot Noir, can benefit from a trace of VA, which in small doses can enhance its floral tones. The presence of VA in dry white wines, however, is widely considered an out-and-out fault

Wine faults: Undeniable flaws

A chemical by the name of 2, 4, 6- trichloroanisole, or TCA, cops most of the blame for cork taint. The truth is there’s a whole family of compounds that can cause a wine to smell musty, or at the very least mask its fruit.

If you thought you might have detected an aroma similar to root vegetables in recent vintages of Loire Sauvignon Blanc or Muscadet, you’re not wrong. Vineyards in this region (and parts of Chablis, Bordeaux and Beaujolais) have been affected by geosmin, an earthy character derived from fungal infections.

Although some wines – particularly light, crisp whites such as Vinho Verde and young Rieslings – have a prickle of spritz on the palate, no still wine should contain bubbles. If yours does, the chances are that the wine still had some residual sugar and yeast left in it at the time of bottling, and is now refermenting in the bottle.

  1. 1. Introduction
  2. 2. Wine faults: Oxidation
  3. 3. Wine faults: Reduction
  4. 4. Wine faults: Brettanomyces
  5. 5. Wine faults: Volatile acidity
  6. 6. Wine faults: Undeniable flaws
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