Friday, December 21, 2007

How to tell a wine is spoiled? – Part 2

With increased interest in wine spoilage, I thought it is timely to give a brief overview on how to determine if the wine is of good quality and if it is spoiled. The basic steps in assessing a wine are as follows: Appearance, Nose and Palate. This is generally applied to a wine that has been poured into a glass and the drinker will focus on these three aspects of the wine. However, when you are in a restaurant or at your own home hosting a dinner party for instance, it may be a little late to figure out if the wine is spoiled after pouring it into the glass. After all, you do not want to be seen serving bad wines. So, there are some simple observations prior the standard 3-step assessment technique.

First, before removing the bottle seal, observe the general appearance of the bottle. If there are wine stains originating from the opening of the bottle, especially if the seal is damp, we can almost be sure that the wine has been exposed to oxygen either due to poor storage condition or the use of poor quality cork. In the case of screw-cap, it may be rare to see this but if there is slippages of wine through the cap, it means either the bottling machine or the glass bottle is not made to specification.

Second, check the level of the cork at the bottle opening. If the cork has been lifted a little, i.e if it is not sitting flat in the bottle opening, it strongly suggest bad storage condition e.g the wine may have been stored in a warm room over an extended period of time. The result could be an oxidized wine and you can pick up the wet cardboard smell upon nosing.

Third, look for the condition of the label on the wine bottle. If the label is crumbled and is not pasted onto the surface properly, it again suggests that the bottle has gone through some temperature swing from warm to cold and vice versa. This alone does not suggest that the wine is spoiled, just that the wine has not been treated with proper care during its shelf life.

Once you are satisfied that the exterior is looking good, we can at least be confident that the wine has been handled properly thus far. The next step is of course to open the bottle and pour a small portion into the appropriate wine glass. The first thing is to study the color and the clarity of the wine. If a wine is too light in color (for a young Red wine) or if it is excessively brown (for a young white wine), it may suggest an inappropriate application of sulfur dioxide. However, the appearance is not conclusive and is only a data point to be considered in subsequent tasting. Clarity is important. If the wine is murky, it is generally not a promising start, especially in white wine. There are some winemakers who opt not to filter their wine (especially Red wine) but the wine should not look murky.

To nose for any spoilage, you will be looking out for odd odors such as rotten eggs or garlic (H2S), bandaid (Brettanomyces), wet cardboard (oxidation), corn chips or metallic bitter finish (high pH wines), moldy or musty (cork taint), nail polish or vinegar (high volatile acidity). Most of these are a result of poor winemaking techniques or barrel storage conditions. However, oxidation may be a result of poor transportation or storage conditions especially when loads of wines are being transported in un-refrigerated container by sea over summer. The heat in the ship storage area over an extended period of time may have the corks expanded and not sit properly in the bottle opening.

As for the palate, a spoiled wine normally gives a SHARP attack to our taste buds or leave behind a trail of very unpleasant finishing. Wines with high volatile acidity will attack our throat like we have just had a mouthful of vinegar. Unusual bitterness is also an indication of spoiled wine, suggesting the presence of spoilage micro-organisms when the wine pH is too high.
In general, a wine is safe-guarded by observing an acceptable range of pH, acidity, alcohol and sulfur dioxide. Unfortunately, during the winemaking process, infections can occur if equipments are not sanitized carefully, storage conditions are not proper. Even if the wine is of good quality upon bottling, transportation and cellaring conditions can also affect the final quality.

Copyright of Wine Treasures Pte Ltd

By Cher Lim
Wine Treasures Pte Ltd

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