Wine Faults
By Ian Love

Sometimes you open a bottle of wine and it doesn't quite smell or taste right. There are a number of reasons this can happen and below are the six common wine faults that could be responsible.

Cork Taint

Cork Taint gives a musty or mouldy characteristic to wine. It has been likened to old socks, wet newspaper, damp cellars and wet soil. Some less affected wines are simply dull and lifeless. Most cork taint is caused by the leaching of a chemical called TCA from the cork into the wine after bottling. The exact sources of TCA are not known, but mould growth during cork growing cycle is strongly suspected as the source.

Oxidation

If a red wines changes in colour from red to brown it will be due to oxidization. The wine can develop a vinegary aroma, fruit characters are subdued and modified, and the palate can become flat, flabby and unpleasant. In white wines, oxidation also causes browning of the colour and changes in both aroma and taste. In mild cases, the wines appear flat, dull and devoid of fruit characteristics. In the more extreme circumstances, white wines can take on Madeira-like flavours and aromas. When advanced oxidation has taken place, the colour and tannin components of the wine will precipitate out, leaving a deposit on the inside of the bottle.

Oxidation is caused by the reaction of oxygen with various components. A little oxygen contact is often beneficial to quality in the development of both red and white wine, but when it is uncontrolled, undesirable effects can emerge. Uncontrollable oxidation can take place at different stages either during the wine making process or after bottling.

Volatile Acidity

Volatile Acidity means there are excessive amounts of acetic acid or the related compound, ethyl acetate. Acetic acid is the major component of vinegar, so affected wines have a distinct vinegar-like aroma; ethyl acetate is a major component of nail polish remover, so affected wines have the characteristics of this material. High acetic acid levels can also cause a sharpness on the palate. The presence of detectable ethyl acetate is almost universally regarded as an undesirable fault in all wine styles. It is caused by some yeast strains which may produce high levels of acetic acid during fermentation, especially under adverse conditions. Acetic acid and ethyl acetate can also be produced from the alcohol of wine by the growth of acetic acid bacteria in the air.

Sulphur Dioxide

Sulphur Dioxide has been used in wine making for hundreds of years because of its preservative properties. Wine made without sulphur dioxide has a limited shelf life and is generally flat and dull. However, when it is used in excess it can completely dominate the nose of a wine and will give you a sharp, prickling sensation in the back of the nose. This is most common in high acid, low pH wines, where sulphur dioxide is present in its most volatile and detectable form. A small percentage of people have allergic reactions to sulphur dioxide, and asthmatics can be very sensitive to it. Maximum total sulphur dioxide levels are regulated around the world to protect wine drinkers, but it is the level of molecular sulphur dioxide that can cause problems. Generally, red wines are made with less sulphur dioxide than white wines

Hydrogen Sulphide

Hydrogen sulphide is also called bad egg gas because of its smell. It is often formed by yeast during the fermentation process. Although it is dangerous when present in very high concentrations in air, it does not have adverse health effects in wine.

Over-Oaking

Oak flavours and aromas are an essential part of several wine styles, and getting the right balance of oak and fruit is a major challenge for winemakers. Wines that have been over-oaked can smell like sawdust or freshly sawn timber. If an excessive amount of oak has been used in the wine, there may be a strong vanilla or smoky characteristic present. White wines can be brown in colour and astringent due to the tannins leached from the oak. In extreme cases, a deposit of wood tannins may be present in the wine.

Ian Love is the owner of Perth Fine Dining Restaurants group, West Valley and Online Wine Store - Raffles Liquor Merchants. Ian also writes a wine blog featuring Australian wines.

Article Source: http://EzineArticles.com/?expert=Ian_Love
http://EzineArticles.com/?Wine-Faults&id=1111013