When it comes right down to it, a ‘bad wine’ can almost always be attributed to a flaw in the winemaking. A multitude of influences can determine how intense a wine is and thus how it is perceived by the taster, but the actual act of making wine is the catalyst between the grape and the glass – between plonk and quality wines. 

Anyone can squeeze grapes to make juice, let it ferment, and settle. That’s the easy part, and it’s quite natural – ever left a container of juice in the fridge too long?

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The legitimacy of any wine, however, is the result of constant attention to detail. Winemakers grapple with potential organic and environmental pitfalls at every turn. The best winemakers anticipate the pitfalls and redirect the wine toward a more enjoyable end. This is true of any wine, whether it is made at home or in a commercial facility.

From the taster’s perspective, any imbalance in a wine can be described ‘bad.’ Anticipating the taster’s perception of a wine several months or years after it has been in the cellar is the real art of winemaking.

There is an arc of potability for any wine. Some arcs are short and steep, leaving an apex of moments when the wine should be consumed. Some arcs are long and even, leaving a wine that can be enjoyed over decades.

On occasion, yes, you might not care for the wine that’s been poured for you – it could be an unfamiliar variety or winemaking style – but there are times when a wine is actually flawed. It could be something as simple as a high volatile acidity, a bloom of brettanomycees, or a poor closure.

Wines today are being made in increasingly hygienic environments by winemakers who are focused on quality. So how do flaws emerge? How do you identify or ameliorate the worst offenders? How do you keep a flaw from emerging in the cellar or once it is in bottle?

Let’s identify a few primary offenders:

Volatile Acidity – (aka: VA; aroma: Nail polish remover) Related to acetic acid, the acid used in the production of vinegar. There is some VA in every wine in the world. Lower levels are found in white wines than red wines, largely because the must is separated from the skins before fermentation. 

Volatile Acidity can be the bane of many a red wine. Extended maceration, cold soaking, high fermentation temperatures, and extended post-fermentation skin contact can all be catalysts for VA. It can be ameliorated with adjustments in pH, sulfur, and by  controlling temperature before, during and after the fermentation, and limiting the amount of time in which unfermenting skins remain in contact with young wine.

Brettanomycees – (aka: Brett; aroma: Mousy, barnyard hay, leather) A spoilage yeast with a tendency to colonize in unsanitary environments. Brett is found in red wines with high pH and low levels of sulfur; and/or red wines with some residual sugar.
Brett is the signature of poor hygiene – or lack of attention to detail – in the winery. It can also be the sign of high pH (>3.5) and residual sugar. When controlled, some Brett can add to the character of the wine. Control begins with cleanliness at every stage of the winemaking process.

If Brett is detected, one fining tool to abet a further bloom is the use of egg whites. The albumin in egg whites binds with the yeasts and settles them to the bottom of the storage vessel. The wine should subsequently be racked from the lees and sterile filtered prior to bottling. There are more high-technology options but they are also expensive.

Aldehydes – (aroma: sherry, methyl esthers) This character is found in wines that are oxidized. Aldehydes, in particular acetaldehyde, form when ethanol (the alcohol in wine) is left in contact with the air (i.e. when an open bottle of wine has been left on the counter for a week). 

Using inert gasses in the winery to protect wine during blending and or barreling creates an anaerobic environment where the ethanol (alcohol) in the wine is out of contact with the oxygen in the environment. Inert gasses are often heavier than oxygen and serve to blanket the surface of any partially filled containers, receiving containers, etc. Nitrogen and argon are best.

Casein, or whole milk, can be used to fine a wine that has been oxidized without stripping the wine of its aromatics. In addition, more sulfur than usual can be used to knock back aldehydes. Unfortunately, aldehydes also bind with free sulfur and can render sulfur useless.

Reduction – (aroma: in the cellar, a lacking in aromas and/or warm rubber character; in bottle, a dirty water or burned match smell) An increase in sulfur compounds – in particular, hydrogen sulfide – due to a lack of oxygen.

Reduction is best handled in the cellar, prior to bottling. Reduction in a bottled wine is, well, unforgiving. Closures such as screw-caps are an easy scapegoat these closures do not ‘breathe’ the way cork does. Reduction can be handled, or ameliorated, by the addition of Copper Sulfate, but high levels of the metal can strip the wine of aromas and flavors. It can also be illegal (i.e. toxic) at certain levels. The best course of action is frequent airing (racking, blending, barreling, sulfuring) wines that have become reduced, during elevage.

By no means is this a complete list of potential wine flaws. But, identifying and navigating each of these hazards can be instrumental in getting a more balanced and enjoyable wine into the hands of the consumer. Beyond these basic ailments, a few guidelines can be helpful when dealing with juice and wine.

White wines like cool fermentations. They are delicate and do not respond to overt oxidation. A lower pH (between 3.1 and 3.5) is generally a good target area. Storage containers should be full at all times after primary fermentation is complete.

Red wines prefer warm fermentations (~ 85ºF), a pH of around 3.5, and should also be stored in completely filled containers after primary fermentation is complete.

Any winery should be clean. Cellar workers should be conscientious of general microbiological functions and correct/hygienic cellar practices. Wine is, after all, an organic product suspended in time by the winemaking process. How long that suspension lasts depends on the attitudes of the people, the tools and practices used to make it.

But, then, everyone has a theory, and an opinion. Individual palates can be specific, particular, even finicky. Ultimately, it comes to the consensus of the group whether the quality of any ‘finished’ wine is ready to drink, age-worthy, or just plain ‘bad.’