Learn About Wine Production
Making red wine is more or less the same process as making white wine, but with some slight variations. For one, skins are kept in contact with the juice during fermentation until the desired color of the wine is reached. Grape skins, it turns out, contain enough dye to give red wine its characteristic hue, meaning thin-skinned wine grapes like Pinot Noir and Gamay (used in making Beaujolais) contain only enough pigment to dye those wines their light translucent reds whereas Cabernet Sauvignon and Zinfandel are thicker skinned and therefore contain enough pigment to imbue the rich dark burgundy or purple hues to their respective wines. In essence, the thicker the skin the darker the wine.
Along with color, grape skins contain tannin. This means because red wine grapes are fermented with the skins, the dry chalky feeling from tannin is imparted to the red wine. This isn’t the case so much in white wine since the skins are removed shortly after crushing or pressing.
Tannin is also found in seeds and stems, the woody stuff of grapes, but these are often removed before starting the fermentation process by a machine called the crusher-destemmer. It’s typically from grapes that are already heavy in tannin, like Cabernet Sauvignon, that the seeds and stems are removed this way. The converse of that would be grapes with less tannin, like Pinot Noir, are allowed to ferment with the seeds and stems to impart tannic qualities, which in turn imparts structure.
Step One: Crushing, Sulfur Addition, Acidification, Chaptalization
As with white wine production, harvested grapes are crushed and/or pressed to render the soupy mush of pulp, pips (seeds), stems, skins and juice called the “must”.
Sulfur, while it can be added, isn’t as much an issue in red wine production as it is with white wine since tannin in red wine grapes acts as a natural preservative to prevent microbial spoilage. However, adding SO2 will eliminate any wild yeasts present in the must that wouldn’t be eliminated naturally.
And depending on the acidic nature of the must or its sugar levels, the wine may go through some acidification or chaptalization, depending on regional law.
Step Two: Skin Contact
Skin contact can happen at any time during fermentation: before, during or after. When depends on the level of tannin naturally present in the grape and how much tannin the winemaker wants to impart on the finished product.
Pinot Noir benefits from early maceration (this is the technical term for skin contact; it’s basically a steeping of sorts between the juice and the skins in order for extraction to take place), before fermentation as it is a low tannin grape. For this process, the wine must is chilled to keep yeasts inactive and kept covered with CO2 to prevent the wine from oxidizing. What this does is it extracts color, tannin and flavor from the skins. This whole process prior to fermentation is referred as a “cold soak”.
Then the wine is warmed to initiate fermentation. The style of wine being made will determine the amount of time it spends in maceration. Two to five days, five to ten days, maybe longer if the winemaker’s intention is to have a highly-extracted, cellar-worthy wine you can store for years.
The rule is the longer the maceration period the longer the aging process needed; the shorter, the more readily drinkable, the softer a wine is.
Step 3: Primary Fermentation
Heat helps extract pigment, tannins and flavors during fermentation. How much heat? Fermenting red wine…about 60 to 85°F. Any higher and the flavors will burn off. Unlike primary fermentation in white wine production, it can take as little as a few days to a couple weeks to complete in red wine production. Which is to say no time at all.
The only problem is in order to obtain proper coloring, tannin and flavors the skins have to remain submerged in the juice. This gets complicated when CO2 released during fermentation causes the skins to float to the top to form a dense compact cap on the juice.
Cap management then becomes crucial to the extraction process. The cap must be “punched” down into the juice repeatedly or the juice must be pumped over the top of the cap to break it up and reintegrate it into the juice.
Other modern methods utilize a rotating fermentation tank that churns the entire must constantly to prevent a cap from forming. Think of a cement mixer… Still others have internal propellers to keep the solids from forming a cap.
We’ll continue to learn about wine next time when I discuss the final stages of red wine production.