You may be thinking I’ve been kidnapped and brainwashed by the natural wine bunnies. Rest assured, nothing is further from the truth. My point is that unequivocal wine faults like cork taint / corked wine (TCA) are uncommon in the big scheme of wine flaws. Most wine professionals who make a business out of assessing quality know that there is a vast grey-area that exists between a) pristine fruit aromas accompanied purely by deliberately imparted winemaking derived characters and b) totally unacceptable faults like obvious TCA taint. Truth be told, the overwhelming majority of wines that we drink reside in that grey-area between the polar absolutes of pristine-clean wines and those possessing so many multiple counts of wine faultiness that they should be classed as hazardous waste. Almost all wines by nature of the fermentation and maturation processes possess by-product compounds that in small doses can contribute a bit of desirable seasoning to wine, in larger doses constitute a certain level of quality compromise and in extremes result in a faulty wine.

Pause that thought for just one sec, because it needs mentioning that an individual’s detection thresholds (levels at which various aroma compounds are detectable) can convolute this whole clean or faulty discussion. Even the greatest wine critics in the world differ in their ability to detect lower levels of compounds such as TCA (corked wine taint) and 4-ethylphenol (a by-product of brettanomyces action). Furthermore, subjectivity (personal preference / tolerance) and can lead to divergent views about grey-area faults. One taster might consider the level of a fault in a wine to be an unacceptable detraction from the fruit and will downgrade the wine’s quality while another taster might find that the same character does not degrade and may even enhance the wine.

What, now one expert’s nectar is another expert’s vinegar? Welcome to our modern day technical tasters’ great schism.

Most if not all of the greatest, mind-blowing old Bordeaux and Burgundy reds I have ever had featured a faint but notable inclusion of brett, VA and/or a mélange of other grey-area faults. Will the modern measures winemakers feel they need to take to assure faultlessness mean that we won’t be making these wines anymore? If the history of wine production has taught us anything, it must be that the biggest rewards seldom involve no risks.

Our ability to recognize and eradicate wine faults has led to more, better quality wines being produced today than ever before. Of this there is no doubt. Yet we are also entering a wine era of black and white views about “faults” and extremist measures to eradicate or embrace them. Let’s ask ourselves this: are the wine fault-phobics really any better for furthering wine quality than those perceived wine fault-huggers - the “natural wine” proponents. I’m not so sure. In my book, while life is too short (and livers are too valuable) to drink bad or unacceptably faulty wines, there is also nothing more boring than a wine that is so clean and sterile that the life has been stripped out of it. More to the point, assuming good old fashioned winery hygiene and handling standards are in place, it is the consideration of a couple of fundamental quality factors – complexity and balance – that should take precedence over stamping out the minor risk of potentially offending grey-area fault compounds when weighing up the trade-off in this faulty debate. Given the choice, I'll take my wine with a pinch of wine faults in favor of what I believe could ultimately be the better, though perhaps not "cleaner", wine.

A Few Dorky Definitions:
acetaldehyde (AKA ethanal)  This is the most common aldehyde in wine, formed by the oxidation of the primary alcohol in wine, ethanol, which can further be oxidized into acetic acid. It has a somewhat bruised / old apple and nutty smell, which in proportion can lend complexity to the nose of an evolving / maturing wine or, in the case of fino sherry, defines the style. In more extreme cases, acetaldehyde can contribute to the faultiness of an oxidized wine, overpowering or detracting from the grape derived characters that may also be fading as a consequence of the oxidation.

brettanomyces (AKA brett)  This is a yeast that exists in wineries and vineyards throughout the world. Some consider brettanomyces to be a “spoilage yeast” that, if allowed, can instill by-products in wine that constitute a wine fault. Others are more tolerant of these naturally existing fungi and contest that a little brett (or rather its by-products) can be seen as seasoning and contribute to complexity. The two by-products of major concern to winemakers are: 4-ethylphenol (4EP), giving rise to sweaty saddles, barnyard, earthy and sometimes medicinal, Band-Aid or iodine notes, and 4-ethylguiacol (4EG), producing smoky, charred, menthol or somewhat spicy aromas of cinnamon stick and cloves. Contesting views over its effect on wine (bad or harmless / a benefit in small does) render “brett” a grey-area fault.

cork taint, corked wine, 2, 4, 6, trichloroanisole (AKA TCA)  2, 4, 6, Trichloroanisole (or TCA for short) is a chemical compound derived largely from the cork stopper in a wine bottle and to a lesser extent from other sources such as wood (oak barrels, roofs, floorboards, etc.) in a winery. There are a few other compounds responsible for “cork” taint, but this is the major one. TCA is generated by naturally-occurring fungi that often exist in the crevices of wood or cork (which is the bark of wood) coming in contact with chlorine compounds, which are ubiquitously present in pesticides, cleaning / sterilizing / bleaching agents and wood treatments, etc. Chlorine is highly volatile; it disperses easily and can travel far from its original source, So it’s often difficult to keep offending fungi from coming in contact with chlorine. When the fungi meet the chlorine there’s an ungodly engendering that occurs, TCA is formed and it ain’t pleasant - pernicious in its ability to instantly spoil a wide range of food and beverage items including mineral water, coffee and apple juice.

cross-flow filteration (AKA tangential filtration)  Such filtration involves a cross-flow filter, which works differently from basic filtration principals that pass liquids perpendicularly through a filter medium to stop particles of a certain size from going through to the “filtered” side. A cross-flow filter works by passing the liquid tangentially over the filter medium (a perforated membrane). This is a very efficient means of quickly clarifying liquid to a high degree as it can quickly strip out very small particles without clogging-up the filter medium by virtue of its sweeping action. Cross-flow filtration is the principal behind reverse osmosis filters, though is not used exclusively for reverse osmosis purposes and is common nowadays as a standard final filtration step prior to bottling wine. The downside of using the cross-flow filters developed for the wine industry is that they can be a little too good at doing what they do. Almost all cross-flow filters are set at a pore size of 0.2 microns, which is small enough to strip out yeast and most bacteria. Here lies the major issue with using these filters - there is a big difference between a “light” final filtration with particle catchers that are only widely spaced enough to take out large particles such as those visible with the naked eye and all but “sterile” filters such as cross-flow filters that routinely strip such microscopic microbials from the wine plus inevitably a certain amount of wine flavor and textural nuances that can lend complexity to wines. On the up side, cross-flow filters can usually clarify wine with one pass, meaning less handling and opportunity for oxidation to occur than other filtration methods (if employed).

ethyl acetate  Ethyl acetate is an ester commonly found in wine formed by the combination of ethanol with acetic acid, which in lower concentrations can contribute a complex lift to wine but in higher concentrations lends an unpleasant nail varnish/polish remover character (being an actual component of some such solvents).

volatile acidity (AKA VA) Volatile acids are naturally occurring components that are present in all wines. The most abundant in wine is acetic acid. When generated in high concentrations above the detection level, acetic acid can impart a distinct vinegar smell in wine. When the vinegar smell of acetic acid notably and negatively impacts the smell of the wine, it becomes a fault and is referred to as volatile acidity, VA, volatile or acetic. But at the more acceptable end of this grey-area fault, some wines and indeed styles possessing relatively high and detectable levels of VA may not call-for a negative tick against quality and there are occasional incidences when it can even make a positive contribution towards balance and complexity. Such is the case with Amarone or some older / mature red wines and styles like a mature Bordeaux or Bordeaux blend reds. Another style exception worth considering is in the case of botrytized sweet wines (where the grapes are infected with botrytis cinerea or noble rot in the vineyard), within which it is natural for a much higher level of acetic acid to be present than in a table wine. In this incidence a very slight whiff of VA on the nose and tang on the palate can contribute balancing lift to the richness of the wine and enhance complexity.

Parts of this article and the glossary have been excerpted from “Taste Like a Wine Critic: A Guide to Understanding Wine Quality” by Lisa Perrotti-Brown MW