Five Main Components in Wine
There are five main components to wine - water, alcohol, acid, sugar, and phenolic compounds.
Water makes up about 80 - 90% of the wine. It comes primarily from the grapes. However, a winemaker may add a small bit of water during the winemaking process.
Alcohol in wine is produced as a result of fermentation. Ethyl alcohol or ethanol is the primary type found in wine. Ethanol is a volatile compound. Therefore, when it evaporates it brings the aromas up to the nose. The alcohol in wine also contributes to the viscosity and mouthfeel. A higher alcohol adds body to a wine and also creates a warming sensation. When a wine is swirled in the glass the higher alcohol wine will have slower and more viscous legs when compared to a lower alcohol wine.
A half percent to three quarter percent of the wine is acid. The acid is what gives the wine that crisp, tart flavor that makes your mouth salivate. There are six main types of acids occurring in wine and wine grapes, tartaric acid, malic acid, citric acid, lactic acid, acetic acid, and succinic acid.
Tartaric Acid is the most prevalent and is found in wine grapes. When a wine is brought down in temperature, tartaric acid can precipitate out and form tartrates, or wine diamonds. To minimize the formation of tartrates, winemakers will cold stabilize a wine and bring it down to a temperature around 25 degrees for about 1 week. This process also decreases the wine’s acidity.
Malic acid is an acid found in wine grapes. It is what makes the wine appear tart and is also found in apples. Underripe and cooler climate grapes will have higher levels of malic acid. Winemakers may choose to lower high levels of malic acid by completing the process of Malolactic fermentation.
Citric acid is found at very low quantities in the grapes. It is added to wines by the winemaker to increase the total acidity. However, when it is added, citric acid will also add citrus flavors to the wine.
Lactic acid is found in wine that has undergone malolactic fermentation. During the process of malolactic fermentation, lactic acid bacteria will convert malic acid into lactic acid. This process makes the wine feel smoother and creamier, and less acidic.
Acetic acid is an acid found in vinegar. It is formed naturally through the fermentation process. It is a volatile compound that can evaporate and be picked up by the olfactory system. At higher concentration the acid can react with ethanol and acetobacter bacteria to develop ethyl acetate. Ethyl acetate is the unpleasant aroma of nail polish remover and varnish.
Succinic acid is found in grapes at low quantities. However, it can be perceived in wine as sharp, bitter, and slightly salty.
Sugar is another component in wine. At harvest wine grapes will have 15-28% sugar content. The sugar in grapes is made of about half fructose and half glucose. The yeast convert these sugars into alcohol during the fermentation process. Higher amounts of residual sugar in wine will increase the mouthfeel and viscosity of the wine. Winemakers may choose to leave some residual sugar in the wine to balance with acidity. Additionally, winemakers may use the sweetness level to hide minor flaws. Wines fermented to dry will still have a minute amount of sugar that is undetectable to taste.
Phenolic compounds are the last main component found in wine. The Phenolics or Polyphenols, Anthocyanins, flavonols, tannins, and vanillin provide a major sensory impact when tasting wine.
Anthocyanins provide the blue, purple or red hue in a red wine and are influenced by the amount of acidity. More acidic red wines will appear redder in hue versus a less acidic wine will appear bluer. As a wine ages, the anthocyanins can precipitate out as sediment. When this occurs, the wine will lose some of its pigmentation.
Flavonols can be found in white wines and provide the golden hue. They are developed in the grapes from being in contact with sunlight. Wines produced from grapes receiving more sun exposure will have a more golden hue in comparison to wines produced from grapes in cloudier locations.
Tannins provide the astringency to wines. They are derived from the skin, stems, and seeds of grapes, as well as the contact with oak barrels. Tannins can be a natural preservative in a wine and prevents oxidation. High tannin wines have the ability to age. Tannins can polymerize into longer changes and precipitate out as sediment. The wine may then be perceived as less astringent.
Vanillin is a phenolic compound found in oak, and is most notably found in American Oak. A barrel will have a higher amount of vanillin when it is medium toast. The toasting helps to release vanillin and provide more vanilla aromas to the wine.
