MAKING RED WINE
What all wine is
Wine is the fermented juice of grapes.
After grapes are picked and crushed, the winemaker adds yeast that mingles with the sugar in the grapes and causes fermentation. (The same thing happens when you make bread, yogurt or beer.) The yeast converts the sugar into alcohol and carbon dioxide.
The carbon dioxide burps off into the air (or, if trapped in a bottle, makes a sparkling wine such as Champagne). The alcohol—around 10%-14% by volume—remains in the wine.
The whole process is simple and ordinary. The most expensive bottle of Bordeaux and the cheapest liter of Tunisian tipple are both the fermented juice of grapes.
By and large, that’s the story for both white and red wines. However, making red wine significantly varies from making white wine.
Seeing red
To be red, a red wine must be made from red (also called “black”) grapes, for it is from the skins of the grapes that the wine gets its color. When making wine, red grape skins are like a packet of dye because the juice of both red and white grapes is nearly colorless.
After picking, the grapes are crushed and their stems, removed.
Photo by Irene Kredenets on unsplash
Fermentation
To begin fermentation, this enormous mass—of pulp, juice, skins and seeds—is put into a large tank (commonly stainless steel, but sometimes wood). If the winemaker does not rely on ambient yeast, yeast is added.
One variation to picking and crushing is called carbonic maceration—often used to make Beaujolais—in which the winemaker tosses, straightaway, whole clusters of grapes into the fermenting vat. The sheer weight of the grapes begins the crushing process and alcoholic fermentation. Another, “carbonic,” fermentation takes place within individual berries. (This way of fermenting augments the fruity character of red wine.)
In either method, fermentation begins and the yeast converts the sugar in the grapes into alcohol and carbon dioxide.
The cap
As the wine ferments, the carbon dioxide pushes the grape skins and pulp toward the top of the fermentation tank. This mass is called “the cap.” However, what’s in the cap (especially pigments and flavoring elements) is what gives the wine much of its color and taste. So, the winemaker often circulates the fermenting juice over and down onto the cap in order to extract as much color and flavor as possible. Sometimes the winemaker will break up and punch down the cap, mixing it with the fermenting wine.
When fermentation is complete—anywhere from one week to a few—the wine is separated from the skins and pulp, either by siphon or by being pressed once again.
Aging
The new wine needs to be aged, even if it is a light and fruity wine. And so it is put into a vat or barrel for a period of time—a few weeks or even upward of two years.
If it did not occur during the normal fermentation, another fermentation called malolactic fermentation is induced while the wine ages. This fermentation changes and softens the wine’s malic acid (from malum, Latin for apple) into lactic acid (like that in milk).
During the time of barrel aging, red wines are often racked—siphoned from one barrel to another in order to freshen them with air and to lift them away from sediments they have deposited. The winemaker also may fine or filter them in order to remove particulates. (Many winemakers nowadays choose not to do this, in order to preserve flavors and body.)
When it has aged a sufficient amount of time, the red wine is bottled and readied for shipment. Often, the bottles rest for a period of some weeks or months before they leave the winery.