Tuesday, September 24, 2019

Wine Flaws and Faults

Today I’m going to talk about wine flaws and faults, and how to recognize these. More importantly we need to learn what we can do to save the wine that appears to be tainted.  I’m sure this must have happened to you at least once, you saved your hard earned money to buy a bottle of wine, you got ready to enjoy it and after you opened it, you realized something was not right, the wine  smelled of any of these things: wet wool, wet dog, sulfur, cabbage, rotten egg, cooked cabbage, garlic, nail polish,acetone, tainted cork, etc. These descriptors are a few of the aromas listed in the UC Davis aroma wheel that reveal to us that we are in the presence of a tainted wine. Somewhere along the way, bacteria or oxygen wreaked havoc. 

Vinification is a very complex chemical process, though enologists have it much easier than in the past, thanks in part to modern technology
, wine flaws/faults still happen.
Wine is a living thing that evolves; from the harvest to the bottle and even after bottling, things can change to the worst. The good news is that in most cases, these problems can be avoided or reverted.

Before I begin to analyze each of these faults, it’s important to distinguish between a flaw and a fault, a wine flaw becomes a fault when it changes/affects the wine completely, we are dealing with wine faults when the wine also becomes undrinkable, for example when it turns into vinegar due onto heavy exposition to oxygen or corky because of the use of a tainted cork. 

We are dealing with flaws, when these are not so obviously detectable, tiny amounts of brett for example may be welcomed and considered an expression of terroir. Or in the case of oxidation that shouldn’t be present in fruity wines, but it is a key aromatic and completely normal to find in Sherry wine.

Oxygen Exposure

Oxygen is indeed needed to make wine but always in the right dosage, too much can and will oxidize any wine, and this can happen in several parts of the wine making and aging process: 1) when the grapes are pressed to extract the juice, 2) it can also happen when the wine is transferred to the barrels and not topped up as they should or top up too often (too much manipulation), 3) it can also happen at the time of bottling if this is not done in the most hygienic conditions. Most wineries use S02 (sulfur dioxide) to prevent this problem and also inert gas. Think what happens to a piece of fruit once you cut it, it begins to brown, the same applies to wine, expose it to air long enough and it will turn into vinegar. Oxidized wines will show aromas of bruised apples, apple juice, sherry, plastic, nuts. Oxidation will also change the color of the wine from light yellow to brown, and in the case of reds from deep ruby to orange or brick.Unfortunately there’s no way to fix an oxidized wine, so if your bottle is tainted, damp it or return it for another one.

Of course, lack of oxygen can cause other problems too, this is also known as reduction and it is a winery practice to preserve fruity aromas in wines, a technique often used in white and rosé wine production. Lack of oxygen can produce reductive aromas of rotten eggs, garlic, burnt rubber, and burnt matches, all of them due to the presence of volatile sulfur compounds. The solution here is micro oxygenation, allowing tiny doses of oxygen in the tank will remove the nasty smells. If you find a bottle with this problem, aerate it for a while, and taste it again. Usually decanting will solve this issue in most cases.

Sometimes, the wine is correct but the problems come from bacteria or mold contaminated corks, this will transfer a corky aroma to the wine. There’s no solution if the wine was affected by this taint, this is why some producers have moved to plastic corks and screw caps.This fault is known as TCA or 2,4,6-trichloroanisole. TCA will give wines aromas of wet basement, wet paper, wet cardboard, wines will appear to be moldy and musty. There’s no way to revert this, so either damp the wine or try to exchange it for another bottle. Some purists who still prefer to use natural corks as wine closures, have invested on steam treated corks, it seems that steaming may be the solution to avoid TCA.

Smoke Taint
Smoke taint happens especially in warm appellations like California or South Australia where fires are common. If there’s a fire near the vineyards, the smoke may travel with the wind and could be absorbed by the skin of the grapes. This will be more noticeable in reds because maceration with skins is a much needed step to extract color, tannins and flavors in red wine production.  A possible solution at the winery could be a process called reverse osmosis, where it is possible to separate elements within the wine and then sort of put them back together again, this time without the smoke taint. 

Brettanomyces is a yeast that lives at the winery, and can affect wine in any step of wine production. Wines with Brett will show aromas of mushrooms, tar, forest floor or barnyard, not necessarily bad in small doses, but if Brett gets out of control, and overwhelms the wine, it can seriously kill its fruit character and yield metallic notes. Proper hygiene at the winery is key to prevent this, as well as proper use of sulfur dioxide and sterile filtration.

Volatile Acidity
 All wines have a little bit of volatile acidity. VA will give wines aromas of acetone and nail polish. It’s produced by acetobacter the same bacteria used to make vinegar. However when volatile acidity is present at lower levels, it is not always considered a fault, and it can help to accentuate some balsamic and fruit notes in the wine. The best way to avoid excessive VA is to control oxygen exposure. It is mostly found in sweet wines and sometimes in reds and whites. Reverse osmosis can help here to remove VA, another option will be to mix the wine with non tainted wine so that VA amounts diminishes on the final product.

Eucalyptus Taint
This happens when there are Eucalyptus trees near the vineyards, somehow the eucalyptus oil travel by air and get into the skins of the grapes. It’s noticeable in reds because of skin maceration, not so much in whites.  It’s easier to detect especially in Cabernet Sauvignons from Australia. However in the right measure, this is expected and not always considered a fault. The wines will show a bit of eucalyptus/ medicinal notes and sometimes this can enhance the wine fruitiness. The solution at the winery is to hand harvest the vines closer to the Eucalyptus trees and to vinify them separately, then blend this wine with the rest allowing more control on the eucalyptus notes. Hand harvesting and sorting may help since Eucalyptus taint may come from barks or leaves that winds blow into the canopy.

Light Damage
Two faults are related to the way wine is stored/kept. The first one is light damage, light damage will cause a wine to oxidize. The best solution is to bottle the wine in green or amber bottles, the problem is with rosé wines that are normally sold in clear bottles, to show their beautiful color. In order to avoid this, it’s important that wine is stored far away from light at the wine store and in your house. (most wine cellars have doors of tinted glass for this same reason). By the way heavy glass bottles will protect the wine from light damage more than lighter ones.

Heat Damage
The second fault related to storage is heat damage, heat causes wine to age prematurely and also causes oxidation and loss of fruit character. In markets such as NY where we can find wines from all over the world, it is important that the wine temperature is kept during wine transportation, wine coming from Australia, South Africa, etc, go through hours of transportation and if this doesn’t happen in refrigerated containers, it can seriously affect the wines. Ground transportation can also create problems during the summer in hot states. The solution is to transport at an ideal temperature of 14ºC or 55 Fh. Wine bottles that have endured heat damage can have aromas and flavors of wines that have been aged for up to 6 years, so measures need to be taken to avoid “cooked” flavors.

Greenness in wine, though this is expected in varieties such as Sauvignon Blanc, that often shows green pepper and grassy aromas, in can become a fault in other varieties. Greenness may happen because of two reasons, 1) unripe grapes, and the solution here will be to better manage vineyard canopies, which will improve even ripeness of the fruit. Or by adding extra hanging time: waiting a bit longer before harvesting, allowing better maturation, reducing and eliminating green flavors. 2) the second reason a wine may show green aromas may come from an insect: the lady bug that sometimes found its way into the fermentation vat. When grapes are pressed, the lady bugs are crushed and end up releasing methoxypyrazines, that cause greenness in wine and give vegetal flavors. The solutions will be to control this pest in the vineyards. Another solution comes by using a vibrating sorting table that will cause the ladybugs to separate themselves from the grapes, preventing their entry into the fermentation vat.

Mousiness is a fault not detected by the nose, but in the palate, so this fault will happen inside your mouth. It usually happens with natural/ organic red wines that had high pH fermentations.  This fault can be avoided by checking pH levels and by using the right doses of S02. Natural wines are more affected because enologists tend to use less amounts of S02, and less filtering. The origins of mousiness is probably lactic acid bacteria, some think that Brettanomyces can also cause this, as well as too much ageing on lees. (this technique is used to give the wine cremosity by allowing the aging of the wine with their dead yeasts after fermentation).
It’s important to notice that not everybody can detect this fault, only 30% of all humans can detect mousiness.

These are faults derived by malolactic fermentation. Malolactic or secondary fermentation happens to most reds and some whites (any enologist can decide whether to allow malolactic or avoid it according to the wine style he/she wants to create) and is the process from which malic acid is converted into softer lactic acid. Some of the aromas obtained from malolactic fermentation come from diacetyl, which produces dairy and buttery aromas/flavors in wine. These are loved by some and hated by others, so here once again it's a matter of taste.

Unbalanced Wine
I left a few lines to this flaw that I find way too often unfortunately! Sometimes it’s too much alcohol, acidity, oak, tannins… if all we taste when we taste a wine, is one element dominating on the others, then we have an unbalanced wine. Of course, in this case the only solution is to change brands or style of wines, though I heard of winos who like experimenting by adding sugar to soften tannins or water to dilute alcohol. Please don't do any of these :)

Until next one! Cheers, Silvina

Sources: "Flawless" James Goode, "Oxford Wine Companion" Jancis Robinson, "Understanding Wine Technology" David Bird.