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Reduced: Commonly used to describe a wine that has not been exposed to air and has developed stinky aromas due to reductive chemical reactions (as opposed to oxidation). Reduced notes in a wine generally result from the presence of volatile sulfur compounds, or mercaptans; these notes include rotten eggs, rubber, struck matches, sewage and even skunk. These off aromas may dissipate after exposure to air through decanting or swirling the wine in the glass.
Malolactic Fermentation (ML): A bacterial fermentation occurring in most wines, this natural process converts sharper malic acid (found in green apples) into softer lactic acid (found in milk). Total acidity is reduced; the wines become softer, rounder and more complex. In addition, malolactic fermentation stabilizes wines by preventing an undesirable fermentation in the bottle. Often called the secondary fermentation. Frequently associated with big, rich, buttery Chardonnay, malolactic fermentation is prevented when fresher, crisper styles are desired.
Mercaptans: Also known chemically as thiols, mercaptans are organosulfur compounds that emit unpleasant, skunky aromas of rubber, sulfur or garlic. Mercaptans are often encountered in wines suffering from reduction (in which case exposure to oxygen may alleviate the flaw) as well as in very old white wines.
Coulure: During flowering in the spring, wind and rain as well as chemical deficiencies can keep grapevine flowers from being properly fertilized, causing these flowers to drop off the cluster. This dropping of flowers is called coulure, or shatter. Since each flower is responsible for a grape, the cluster of grapes that eventually forms is loose and missing grapes. If the improperly fertilized flower stays attached, it produces a puny, seedless grape called a "shot" grape. Although the yield is reduced, there is a corresponding benefit—loose clusters that allow for increased air circulation are less susceptible to rot in humid conditions.
Flowering: The emergence of tiny blossoms on grapevines in late spring. An important time of year, since spring rains and winds can disrupt flowering, reducing the potential crop.
Smudge Pot: Oil-burning heaters used to prevent or reduce frost damage in orchards and vineyards. Typically consisting of a wide base topped by a chimney, smudge pots may be lit when frost threatens. They offer some protection by creating air currents that can disrupt settled colder air at ground level. Due to their consumption of oil and smoke production, as well as labor requirements, use of smudge pots is in decline in favor of other frost-protection methods such as wind machines and aspersion.
Éclaircissage: French term for green harvest, or crop thinning. Grape bunches are removed to improve air flow through the canopy, facilitate the ripening of the remaining bunches and reduce the crop yield.
Resveratrol: Polyphenol found in grape skins and wine as well as in other foods such as peanuts, blueberries and cranberries. It is believed to be the source of wine's health benefits; studies have linked resveratrol with improved heart health and endurance as well as reduced risk of age-related degeneration, Alzheimer's disease, arthritis, blindness, cancer, obesity and type 2 diabetes.
Oxidative: Refers to winemaking practices that deliberately expose the wine to oxygen, such as the use of open-top fermentors and racking. Traditional winemaking exposes the wine to some air, but does not result in oxidized notes. An aggressively oxidative approach can result in nutty notes, as seen in wines such as Sherry or vin jaunes from the Jura.
Reductive: Refers to winemaking practices that reduce a wine's exposure to oxygen, such as the use of stainless steel tanks and inert gases to minimize contact with air. This is done to maximize a wine's fresh fruit flavors. However, in some cases it can result in "reduced" aromas, considered a flaw.
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