Wine is complex and ever changing - consider the complexity of the underlying web of differing chemical and bio-chemical influences at work in a wine - and sometimes things go wrong. Wine faults vary in intensity and some can be barely detectible merely reducing potential pleasure, while others may make the wine totally undrinkable.  Sensitivity to various faults can differ vastly from taster to taster.

Most wine faults come from poor winemaking or defective materials such as corks.

·         Cork - This unpleasant musty, mouldy aroma is caused by a chemical called Tricloroanisole (TCA) which contaminates porous surfaces such as cork or wooden barrels. Apart from the very unpleasant smell the wine is also flat and bitter.

·         Oxidation - When a wine has been in contact with to too much oxygen, it develops a sherry-like character. Oxidised white wine will develop a curious dull browning, premature to its age. Red wines are slightly more robust but also develop pre-mature browning and loss of fruit and freshness and has a stale, bitter aroma. Ageing is a slow oxidation process and desirable for the development of flavour, but accelerated oxidation  due to poor winemaking, or a cork with an imperfect seal, is irreversible in the bottle and renders the wine undrinkable.

·         Over - sulphured - Sulphur is an anti-oxidant and anti-septic and therefore essential to keep wine healthy. Over-sulphured wine smells of burnt matches and leaves a sour taste in the back of the throat. Sulphur levels are kept much lower today than twenty or thirty years ago.

·         Acetic Acid /Volatile Acidity - This is found in all wines at varying levels and there is a fine and ever-shifting line between virtue and fault. In excess it will make a wine smell and taste sharp, vinegary and fiery with and acidic finish. The solvent -like aroma of nail varnish remover is a dead give away. At low levels it lifts the aroma of the wine.

·         Brettanomyces - Mousiness or Brett  - as it is commonly called - Unpleasant taint derived from microbiological spoilage caused by a yeast called brettanomyces. It reacts with an amino acid in the wine to form an odour suggesting ammonia or mouse droppings. It can be prevented by maintaining sufficient sulphur levels in the wine. Once infected the taste cannot be removed.

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