Wine 101 – What wine is made of

Written by Posted on 06 24, 2016
What Wine is Made of |

chemistry of wine

Wine 101 – What wine is made of

In its simplest terms, wine is made by fermenting grapes and pressing the liquid out. Winemaking or vinification, is the production of wine, starting with selection of the grapes or other produce and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruits or plants. The science of wine and winemaking is known as oenology. A person who makes wine is traditionally called a winemaker or vintner.  However, the purpose of this post is to explain what wine is composed of and not the process of vinification.

So what is wine really composed of?

85% Water

There’s a reason for the ancient tradition of drinking wine besides the pleasure of its alcohol content: wine is mainly water. Long ago, wine was safer to drink than water because it was less prone to dangerous bacterial contamination. This was particularly true in warm regions where water was rarer could get spoiled more easily. This is perhaps why the story of wine started in warm and dry regions around Mesopotamia.

13(ish)% Alcohols

It’s no secret, wine contains alcohol. The alcohol is produced when yeasts consume the sugar in grape juice, turning it into alcohol and carbon dioxide. The alcohol percentage (referred to as alcohol by volume or ABV) varies from wine to wine. Wines on the low end contain around 7%. These are often sweet wines whose fermentation stopped early, leaving unfermented sugar. Naturally fermented wines rarely go over 15% alcohol because yeasts run out of sugar to ferment. High alcohol wines (14% to 15%) are generally from warm regions where grapes reach a high level of ripeness with high concentrations of sugar. Only fortified wines have alcohol percentages of 17%-20% or higher. Fortified wines are essentially wines to which high-strength spirit has been added. The process of adding alcohol to wine or grape juice is called fortification hence the name fortified wines.

1% Glycerol

Chemically, glycerol is an alcohol, hence the ‘ol’ at the end of the word. It doesn’t have any effect on our nervous system, and our bodies treat it more like a sugar. Glycerol is a byproduct of fermentation, generated by the yeasts as they transform sugar into alcohol. Glycerol is has an oily texture that brings viscosity to wine. A cool fact: glycerol tastes rather sweet, which partially explains why some wines taste a bit sweet though they contain very little sugar.

0.5% Acids

Acidity in wine is measured in pH, usually between 3 and 4. It is often more acidic than orange juice, but less than most sodas. The main acid in wine is called tartaric acid. The grapevine in one of the very few plants to generate tartaric acid; as a result, most bacteria are unable to metabolize it. This is why wine is so resistant to spoilage.

Carbohydrates (sugars)

Obviously, the concentration in sugar in wine can vary greatly depending how ‘sweet’ the wine is. Very dry wines have virtually no sugar at all, and some sweet ones can contain over 200 grams per liter. However, most wines, even dry ones, contain between 0 and 10 grams per liter (g/L) of carbohydrates.

Sugars in wine are mainly the natural fruit sugars: fructose and glucose, generally in equal proportions. However, wines can contain small but significant quantities (1 or 2 g/L) of unfermentable sugars. Like the name indicates, they cannot be fermented by yeasts or bacteria. They therefore remain in the wine as “residual sugars” and provide some sweetness.

0.1% Phenolics

Despite their relatively small proportion, phenolics are a big part of what make wine special. Phenolics called flavonoids and anthocyanins give white and red wines their distinctive colors. The tannins that provide wine’s drying astringency and some bitterness are also phenolics. Tannins are in much higher concentration in red wines, although whites contain small quantities.

And that’s it! Lots of water and a few powerful molecules come together to make the amazing variety in every glass of wine you drink.

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