Wine Blog

December 10, 2008

Wine Chemistry 101:
The Components of Wine

As your interest in wine progresses, it can be helpful to understand a bit about the basic chemical components of winegrapes and wine:

Sugar - Obviously, grapes are sweet. When the grape's natural sugars are fermented into alcohol, you get wine. In some cases, fermentation stops early, and residual sugar can be left behind. This can vary from trace quanities to slightly higher levels such as in 'off-dry' wines, or the high residual sugars in dessert wine.

Alcohol - In winemaking, sugar is converted to alcohol. Typically, red wines have more alcohol than whites, since red grapes are harvested later when grapes are riper. Wines from warm, sunny regions also tend to have more alcohol. Alcohol percentages can range from 8% to as much as 16-17%.

Acid - Tartaric acid and malic acid are the most important acids in grapes. Tartaric acid is rarely found in other fruit, and gives grapes and wine their 'tart'ness. Malic acid can be found in other fruit, especially green apples. Many wines go through a secondary 'malolactic' fermentation (ML), where malic acid is converted to lactic acid. Lactic acid is softer and has a creamy texture (it is found in milk). Almost all reds go through this process, but some white wines have no ML - they will have a bright crispness and green apple flavor - or with 100% ML - they will be creamy and buttery. You can also find whites with varying degrees of partial ML that will have qualities of both.

Tannin - Bitter and astringent, tannins are found in plants, typically in leaves, stems, seeds or fruit skins. During production of white wines, grapes are immediately pressed after harvesting, removing the juice from the other parts of the grape bunch, so white wines have little to no tannins. However, during red wine production, grapes are fermented together with skins, seeds and sometimes stems, and tannins are extracted into the wine. This is why red wines give you more bitter flavors and oftentimes that drying, puckering texture on your tongue.

Next Article:    Wine Pairing Chemistry
 
>back to Wine Blog Home