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- ACETIC ACID
- The primary acid in vinegar. Created by a wild bacteria (acetobacter) which, in the presence of oxygen, metabolizes ethanol into acetic acid. The presence of this substance in noticeable quantities spells doom for a batch of wine or beer. It can be avoided by careful sanitation techniques and closed fermentors with minimal air space. Wine seriously infected with acetobacter can be made into good vinegar if the winemaker is willing to swallow his/her pride and jazz up his/her salads.
- ACID BLEND
- Usually a mixture of malic, tartaric, and citric acids. Used by winemakers to correct low acidity levels. In many wines, the blend is preferred to any one acid for its roundness of flavor. Wines made from vinefera grapes may benefit from the use of tartaric acid instead.
- ACIDITY
- Acidity may refer to the sourness, pH, or total titratable acid content of a wine (or beer, especially in some Belgian styles). Acidity is a major component of wine's flavor, and it contributes to the natural preservative qualities of wine which extend its shelf life far beyond that of beer.
- AEROBIC FERMENTATION
- Fermentation in the presence of oxygen. Yeast may metabolize with or without the help of oxygen, although alcoholic fermentation is associated with anaerobic fermentation. The presence of oxygen in the first few days of fermentation aids in the synthesis of important structural components of yeast cells, helping the yeast achieve appropriate population levels for active anaerobic fermentation to begin.
- ADJUNCTS
- Any secondary source of starches and/or sugars used in brewing, the primary source being malted barley (or wheat). Adjuncts include (but are not limited to) flaked cereal grains, sugars, syrups, corn, and rice. The lack of malt flavor in major American beers is due to their use of high proportions of adjuncts, which generally add 100% fermentable sugars. These sugars are completely fermented to alcohol during fermentation, leaving no residual flavor or body. The similar lack of hop flavor in major American beers is due to their use of virtually no hops.
- AIRLOCK
- Most commonly a plastic water lock which allows the carbon dioxide produced by fermentation to escape, while preventing the influx of outside air (which may carry infectious microbes). A blow-off tube can also be used as an airlock during primary fermentation.
- ALCOHOL
- Actually a family of organic compounds, the common term "alcohol" refers to Ethyl Alcohol or Ethanol, CH3CH2OH. Alcohol is poisonous by degree to lifeforms small and large, which accounts for the preservative qualities and the hangover potential of any alcoholic beverage.
- ALCOHOL CONTENT
- The percentage of alcohol in a wine or beer. It may be measured as the percentage of the total volume (Alcohol By Volume, ABV), or as the percentage of the total weight (Alcohol by Weight, ABW). Since alcohol is less dense than wort and water, Alcohol by Volume is the higher of the two values.
- ALKALINITY
- The opposite of acidity, alkalinity is the prevalence of ions which neutralize H+ ions. A "base" is highly alkaline, or "basic." Usually alkalinity is due to OH- ions which can neutralize H+ ions, although other bases can be responsible for alkalinity.
- ALL-GRAIN BREWING
- The use of raw malted barley as the primary source of malt sugars in a brewing session, as opposed to the use of malt extracts. Since all-grain brewing requires mashing and sparging, it is considered the "advanced" form of homebrewing.
- AMELIORATION
- Adjustment or correction of a wine must before fermentation, usually referring to addition of sugar or acid where lacking in the original fruit.
- ANAEROBIC FERMENTATION
- Fermentation in the absence of oxygen, whereby yeast harvest matter and energy by processing sugar into alcohol, carbon dioxide, and important flavor byproducts.
- APERITIF
- A fortified or high-alcohol wine intended to be consumed before dinner.
- AROMA
- The component of flavor perceived in the nose--in fact, it's often called the "nose." Since the tongue can only express four attributes of flavor (sweet, salty, sour, and bitter), aroma is extremely important in the perception of flavor. This fact is brought to the forefront whenever a person with a stuffy nose eats food, which in the absence of aroma seems completely devoid of flavor. In wine jargon, aroma and bouquet are closely related.
- ASCORBIC ACID
- Also known as vitamin C. An effective agent in preventing oxidation of a wine.
- ASTRINGENT/ASTRINGENCY
- The mouth-puckering or mouth-drying quality of a wine or beer. Often perceived as extreme "dryness," as in Cabernet Sauvignon wines. Astringency is related to tannins leeched from the skins of the grapes or fruit, or secondarily from the stems and seeds or oak barrels. The astringency of these tannins mark the major differentiation between white and red wine, after color. Although harsh in abundance, tannins help prevent oxidation and can extend the complexity and aging potential of a wine. It is for this reason that most wines suitable for long-term aging are based on highly tannic grapes. Harsh astringency in a young red wine can be softened somewhat by allowing the wine to "breath" before being enjoyed. Decanters are often used for this purpose.
- ATTENUATE / ATTENUATION
- The ability of a yeast strain to ferment the sugars in a wort or must. Attenuation is more important in brewing, where a blend of complex wort dextrins and sugars must be broken down by the yeast during fermentation. Variations in yeast strain attenuations and brewing conditions will affect the dryness and body of the finished beer. See also, Flocculation.
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