WHAT CAN CAUSE WINE DEFECTS?

TCA

TCA is an innocuous natural chemical compound that results from the activity of certain molds in the presence of moisture; if they are in the presence of trichorophenol they are able to metabolizing it into trichoroanisol. It may be found in bottled wine, beer, spirits, soft drinks, food and packaged food products and cork stoppers. TCA is the main agent responsible for the organoleptic deviation associated with the musty aroma and taste in wine. Sensory detection of TCA can occur at extremely low concentrations and is often measured within a range of nanograms per liter of wine. One nanogram per liter is often expressed as one part per trillion (ppt) and is roughly equivalent to a grain of sand placed in an Olympic size swimming pool.

Individual detection of TCA in wine depends on a great number of variables including the wine matrix, the sensory environment and individual sensitivity to TCA. Tests of trained personnel under sensory controlled conditions suggest a range of sensory detection from 2ppt –10ppt in white wines. The average level of sensory detection was 6ppt.

Oxidation
Oxidation occurs when wine is overexposed to air. It shows itself by a stale off-odor, and the loss of fruity aromas in the wine. Natural cork assists in the prevention of oxidation with its ability to seal the wine bottle. Natural cork has the ability to be greatly compressed and then quickly expand back to its original size. These compression/expansion properties, in combination with the natural cork coating’s interaction with the glass of the bottle, promotes a complete seal.

Reduction
Reduction occurs when there is a lack of oxygen within a sealed bottle of wine. The sulfur compounds that naturally form during the production of wine require an interaction with oxygen within the bottle. Without this interaction, off characteristics can occur, such as the smell of rotten eggs, cooked cabbage, or sewer gases. Natural cork prevents this reduction by seeping small amounts of oxygen out of the natural cork over time.

Mercaptans
Mercaptans are produced in wine by having hydrogen sulfide react with other amino acid-containing components, such as ethanol or sulfur. They can be formed as a result of reduction, when disulfides within bottled wine revert to mercaptans. Mercaptans are easily detected by the human senses, being noticed at only 1.5 micrograms per liter. The common aroma descriptions of mercaptains are onion, rubber and skunk-like odors. Once formed, mercaptans are very difficult to remove and removal is usually only temporary. With its ability to prevent reduction, natural cork also prevents the formation of mercaptans.