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  • 10 May 2020
  • Wine 101 Guides

Wine Flaws #1 — Faulty Wine

The dictionary gives us two definitions of "fault:"

1. An unattractive or unsatisfactory feature

2. Something that is wrong with a machine or system

Either way, if you’re a winemaker and someone deems your wine to be faulty, it's bad news. The word itself is a strenuous word; a harsh, rejectory term. It brands the wine less than satisfactory; to some degree a failure. It might even give you the impression that something is inherently wrong with the wine.

Quality regulation tasting panels have the ability to dismiss a wine, either for export or even for any commercialisation whatsoever, even if the customer is made aware of the fault in question. If a wine is rejected in some markets, it will be deemed illegal to sell and forced to be poured down the drain, hundreds, sometimes even thousands of bottles at a time. 

It is important to recognise that some faults are inherently faults. These are usually irreversible, and often render the wine undrinkable. In extreme cases, they might even make you stare at the glass, panic stricken, wondering how on Earth wine can deteriorate so disastrously. 

Wine is subjective, and as such some are arguably not faults; these will be published separately. What do we call these non-faults? Well, it depends on their character and poignancy. We could argue that instead of flaw, we should embrace language such as “quirk,” “eccentricity,” or even “brazen” and “cheeky.”

That said, sometimes, a fault is inevitably a fault. Sometimes, a wine is broken.

Faults due to Bad Storage

When a wine’s elements are in harmony and when a bottle is stored correctly, wine can last for decades, even centuries. There are stories of shipwrecked wines from the 1800s and even Vin Jaune from 1774 that tasted almost as though they were created yesterday.

However, bad storage of wine is often the wine’s worst enemy and this produces two particular faults. One, you might have guessed (heat damage), and one, you may never have heard of (light damage and light strike). Both are capable of ruining wine.

Heat Damage

Heat damage can affect a wine subtly, or it can utterly destroy a wine. Often, it is in the hands of the producer and shipping companies to ensure that the wine is not exposed to heat for significant periods of time. During heatwaves, often producers will cease to ship in order to avoid the chance of heat damage occurring. When it does occur, it oxidises the wine.

If this is very subtle, for example if the heat has not been so extreme, the wine might seem slightly subdued, but still be pleasant.

In the worst cases it might totally be lacking in fruit, seem like it’s many years older than it is, or even be brown. In bottles under cork, the cork might even be pushed out. 

Faults due to Light

This is more common than you would think, and is largely caused by the growing fashion for clear bottles. Clear bottles, while they might show off the colour of the wine, also let in far more light than amber and green bottles. It is estimated that clear glass may block only around 10% of harmful rays, whereas amber can block around 90%.

Light Damage

There are many complex chemical reactions that may take place in the wine when exposed to light for prolonged periods of time. The first possibility is the formation of glyoxylic acid, which binds with any free SO2 in the wine, meaning the wine is no longer protecting itself. If there is no SO2 or all the SO2 has already been depleted, then it may cause browning of the wine. 

Light Strike

In French, this is called gout de lumière, meaning the taste of light. Unfortunately, however, this poetic-sounding “taste of light,” in reality tastes like cabbage and sewage. It is caused by the production (specifically photogeneration) of mercaptans and dimethyl sulfide, both of which are two of the nasty types of reduction, caused by light exposure.

The common misconception is that light damage happens over a long period of time, but in reality it can happen in a matter of hours. So, if you have clear bottles, make sure to tuck them away somewhere where they see less direct light.

Bug Taint

These are really bad luck for the winemaker. They can only be avoided by ensuring that the bug in question cannot enter the fermentation vats.

The key culprits are ladybugs and fruit flies. Ladybugs release compounds that give tastes like peanuts or asparagus, that dominate the wine. Just one tiny fruit fly, meanwhile, can ruin a glass of wine. Imagine what a group of them can do to an entire vat! The bitter, vinegar-like taste they produce is caused by pheromones released by the female fruit fly to attract male, so this particular fault is caused by females (apologies on behalf of us all).

Cork Taint & its Evil Pals

The cork we use for wine bottles comes from the cork tree. The tree itself is not cut down, it is simply “shaved” off the side of the tree, meaning that the production of cork is highly sustainable. There is also something romantic about the cork. It seems almost ritualistic when pulling the cork out of a bottle of wine; that satisfying pop, followed by the gentle glugging of the liquid escaping its glass home. Then, the delightful woody smell of the cork brings back joyous memories of previous bottles shared.

Well… most of the time.

Sometimes the cork pops out, the wine glugs out, you smile in anticipation, lift the glass to your nose and…

“Eugh. WHAT?! Why does my Riesling smell like wet dog?!”

The most common cause of cork taint is a compound called TCA. if the wine is mildly affected, it might seem normal but muted, perhaps even with the tiniest hint of cardboard somewhere, a bit like annoying background noise. In bad cases, the wine almost no longer tastes like wine, instead it just tastes like your grandma’s damp cellar. It is irreversible and affects around 5% of wines bottled under cork to some extent. Due to modern technology developments, this statistic is decreasing.

It is caused by fungi coming into contact with chlorophenol compounds. Often, these occur due to a residue that exists in forests from insecticides used between the 50s and 80s; a scary reminder at the potency of the capacity of chemicals to remain in the environment. Other musty-causing compounds have also been identified both in the cellar environment and in barrels (a cooperage problem), so it’s not always the cork that’s the cause of this evil smell. 

Smoke Taint

In fire-affected vineyards, grapes can be devastatingly affected by smoke from many miles away. It's not so simple as just washing off the smoke: the phenols from the smoke actually bond inside the grape itself. Once this happens, it's doom and gloom. Even if you can't taste the smoke in the grapes, once fermented, they bonds are broken down and the taste comes back. Unfortunately, there's not much that winemakers can do to avoid the problem. Making wine with little maceration might help - as it means less contact with the skins - as well as more invasive techniques such as reverse osmosis and carbon fining. Some believe that ageing might help, whereas others don't: there is no clear answer, and there is a lot of research currently being undertaken.

In the unfortunate case of all these faults, there is simply nothing to do. If the fault is very subtle, you might be able to get away with it in a spaghetti bolognese. It is frustrating, but such is life. It only makes us appreciate Great Wines even more.  

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