To Be or Not to Be: Wine Faults – Part One

When I write about wine aromas and flavours, I tend to focus on the positive ones: the appetising compounds in wine, which bring us pleasure and make us take another sip. But wine, like life, isn’t all about peaches and cream. So in this series I want to zoom in on wine faults: what are the most common ones; what causes them; how to recognise the problem and, when possible, how to deal with it.

But First: Perception of Wine Faults

Wine faults cause much debate among tasters of all experience levels. First of all because we have different physiologies, preconceived ideas about wine and varying philosophies on life, on what we eat and drink.

Our individual detection thresholds for certain aroma molecules, or the number of flavour receptors we have on our tongue for certain compounds in wine, can vastly differ. I myself, for instance, am particularly sensitive to cork taint in wines (and aromas in general), while my husband – an excellent taster in his own right – will often not notice it in very small amounts. He, in turn, is more sensitive to bitter flavours than I am. As a result, wines with a high number of bitter phenolic compounds, especially in combination with higher alcohol and tannin levels, will seem more unbalanced to him than it would to others. As a bonus, it helps him in blind tastings to determine a wine’s alcohol percentage with uncanny accuracy.

These differences are largely based on genetics, but it’s important to know that, through training and experience, you can increase your sensitivity, your awareness and your ability to correctly identify aroma and flavour components.

Be that as it may, you can imagine when, in a group of wine tasters, people are not aware of these physiological differences, haven’t taken the time to calibrate their assessments, or simply don’t understand their personal sensory strengths and weaknesses, this can easily lead to lengthy – and quite pointless discussions. ‘Oh yes there is’. ‘Oh no there isn’t.’ Add posturing, age/gender/experience/credentials and the fear of losing face to the mix, and you get a fascinating, be it rather explosive, social cocktail. First world problems, but still… 😉

Even when tasters can agree on the presence of a certain compound, this doesn’t automatically mean they will all consider it a fault. One person’s peeve can be another person’s bliss. Think about it this way: would you say the beauty marks of Marilyn Monroe, Cindy Crawford or Angelina Jolie are flaws, or instead assets that make their faces more characterful and unique? Do the mysterious scar on Joaquin Phoenix’ upper lip, or Anna Paquin’s teeth gap, detract from their qualities or rather make them more interesting?

Many wine folks will consider a wine with noticeable amounts of ‘Brett’, a range of aromas reminiscent of horse sweat, farmyard or sticky plasters, faulty. While to others these musky, meaty spice aromas add character and complexity to a wine, even making it a more versatile food partner.

1. Cork Taint

Wine corks

The one flaw just about everyone will agree on, is the infamous cork taint. In extremely low amounts, many won’t detect it, but when it’s obvious, there’s no discussion that this is a wine fault and not a beauty mark.

Cork taint is a collective name for a series of contaminations, which cause a wine to smell musty, like wet cardboard or damp, mouldy cellars. It also reduces your perception of fruity aromas in wine. (As an aside: these fruity aroma compounds haven’t actually disappeared from the wine, but cork taint mutes the sensory receptors in your nose, so you can no longer detect the pleasant aromas and flavours that are there.)

So even if you don’t actively smell ‘corked’ aromas, but a wine tastes unexpectedly dull, uninteresting and lacks fruit, it might still be contaminated. If you’re uncertain, take a sip of the wine, paying attention to the (lack of) fruit flavours, and keep the wine in your mouth to warm up. In most cases, light cork taint will become more apparent on the palate.

Cork taint is caused by a number of chemical compounds, of which TCA is the most common culprit. TCA is short for 2,4,6-trichloroanisole (if you want to be fancy about it), and it is a by-product of the interaction between so-called chlorophenols, and naturally occurring bacteria or fungi in the air around us. These chlorophenols, or TCA itself, can enter the wine or winery in different ways. The most common is via natural corks, when TCA develops in the bark of cork oaks due to chlorophenol-containing pesticide residues in the soils. The risk there is that other corks from the same batch (and therefore likely more wines from the same batch too) will have the same problem.

But even wines closed with a screwcap or with synthetic (‘plastic’) or glass corks, can be affected by TCA. This occurs less frequently, but it can still happen, because chlorophenols are used as fungicides (e.g. on pallets or other forms of wood equipment or packaging) and in bleaching or sterilisation processes of i.a. wood and paper.

It is estimated that between 3 and 5% of the bottles with a cork closure are affected. Because TCA in wine occurs only in minute quantities, drinking a corked wine (or cooking with it), is not considered harmful to your health. But since it’s unlikely to make you profoundly happy, it’s best to return the (open but undrunk) bottle to the wine store where you bought it. Many wine merchants will simply replace the bottle by a new one, or give you a refund. If the problem occurs in a restaurant, the sommelier or waiter will bring you a new bottle or suggest a valid alternative.

A rumour which circulates in wine circles, is that you can ‘fix’ a corked wine by putting plastic wrap / cling film in your glass or in the bottle. Or by pouring the wine into a container with a wad of plastic wrap in there. The underlying explanation is that PVC attracts TCA molecules, so the fewer of those which remain in your wine, the less they serve as a masking agent for the pleasant aromas. (Source.)

Do take into account that plastic wrap is increasingly made from other materials than PVC, such as low-density polyethylene or LDPE, which is considered to be safer for the body. But because LDPE does not have an effect on cork taint in wine, chances are that your kitchen cling-wrap experiments won’t do the trick. I’ve tried it a few times myself, with different brands of plastic wrap, and the results were minimal. Additionally: the whole process is messy, and doesn’t add to the charm and overall atmosphere of tasting, drinking and enjoying wine. So I no longer bother.

2. Brettanomyces or ‘Brett’

If you’re a craft beer lover, chances are you’ve already witnessed (or partaken) in discussions about ‘Brett’. Here in Belgium, the land of world-famous trappist and lambic/gueuze beers, we don’t mind a whiff of horse blanket or barnyard in our glasses, as it adds to the beer’s unique personality. But in many parts of the world, and for many tasters, these aromas are considered contaminants, and highly undesirable. In wine too, Brettanomyces is a debated topic, with passionate advocates on one side, and harsh opponents on the other.

Brettanomyces is a genus of yeast – a member of the Saccharomycetaceae family. It is therefore a relative of the more famous Saccharomyces cerevisiae, which is the most important yeast species used in winemaking and brewing, but also in baking, as a leavener for i.a. bread or pizza dough.

As yeasts do, just like its Saccharomyces cousins, Brett consumes sugar in the grape must, and produces a range of chemical compounds that affect the aromas and mouthfeel of a wine. Unfortunately, the aromas produced by Brettanomyces are not of the kind we’d happily bottle and use as perfume. The main wrongdoers being:

  • volatile phenols:
    • 4-ethylphenol (4-EP): smells of sticky plasters, barnyard, manure;
    • 4-ethylguaiacol (4-EG): smells of cloves, spice, smoky bacon;
    • 4-ethylcatechol (4-EC): smells sweaty and horsey;
  • fatty acids (i.a. isovaleric acid, isobutyric acid, pentanoic acid): smell of horse sweat, horse saddle, stale cheese, sweaty socks. (Source.)

Brettanomyces is considered a wild or ‘rogue’ yeast and a spoilage organism. These microscopic cells are commonly present in vineyards (e.g. on the grape skins), and in cellars (e.g. on cellar surfaces, winemaking equipment and in used oak barrels). For Brett enthusiasts, this adds to the idea that it is part of a vineyard and a winery’s unique terroir. For others, its unpredictable nature and peculiar aromatics make it a wine fault, to be combatted with all means necessary.

Brett occurs most frequently in red wines. Less so in whites, because the yeast tends to flourish in wines with lower acidity / higher pH, and white wines in general have more acidity than reds. Also: both 4-EP and 4-EG are synthesised from polyphenols that come from the grape skins and are more prevalent in black grapes.

Winemakers who do not want any Brett influence in their wine, need to be rigorous when it comes to hygiene, in all stages of the winemaking process. Starting with the diligent removal of rotten grapes from the harvest to limit spoilage. Then in the winery, frequent chemical analyses need to be performed to detect any contamination early on. To prevent and control yeast spoilage, winemakers have a range of options at their disposal, from the addition of sulfur dioxide to careful management of temperature and pH during winemaking. If that didn’t do the trick, there’s still the option of filtration or treatment before bottling. (Source.)

But Brettanomyces isn’t all bad. In small amounts, it can add layers of complexity to a wine. Therefore much depends on the quantity, but also on the specific yeast strains. A hint of ‘horse stable’, cloves, spices or leather in a powerful red wine can add an alluring primal, musky, savoury quality to the mix. While a heavy blanket of medicinal plasters, manure and stinky feet is probably not what most wine drinkers are after…

Here too, what will be considered ‘a delectable whiff’, or ‘just too much’, will largely depend on the individual, and on which dishes you want to pair with the wine. I myself don’t mind a bit of funk in a good red. In moderation, as long as it doesn’t overpower the fruit or starts to smell like the countryside on an overactive farming day.

A touch of Brett can even add to a wine’s food pairing potential. Think of dried and cured meats, for example. Or wild game, meat pies, pâtés, Flemish beef stew (‘stoverij’ or ‘carbonade flamande’), glazed barbecued ribs, leg of lamb, organ meats, root vegetables or flavoursome mushroom dishes. When it comes to food pairing with earthy, meaty and gamey ingredients, a bit of Brett from a good-quality, balanced red wine, will act as an aroma bridge between the dish, the herbs and spices in the seasonings, and the fruit and spice aromatics of the wine itself.

How do you feel about Brett in wine? Feel free to share your thoughts and experiences in the comments below. 🙂


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