I always say wine making is like a mathematics equation full of variables. If you alter one variable the sum of the equation changes. There are a few basic steps in this process. Like cooking, when the structure is understood, the door opens for experiments and innovation. I believe there are no absolutes and only a few truths in the world of wine. You can always find somebody going against the grain (pun intended) and doing just fine.
- It seems best to me to start the explanation with white wine. White wine making is a shorter process than red wine. Red wine is just a variation of the same process.
White wine is made from white OR red grapes. This is because the juice inside all grapes is clear. For example, Pinot Grigio is actually a red grape. The “grigio” in the name (meaning grey in Italian) refers to the color of the grape skin. We will discuss what gives red and rose wine their color next.
The grapes are sorted to remove any debris. The Stems are removed and the grapes are then crushed. As the wine press fills, the juice from the lightly crushed grapes begins to flow. The first bit of juice is the “free run” juice.
Then weight is applied mechanically to get the first pressing. Then there is second press. I explain these steps because it is important to know that the free run juice is the highest quality. The first press is a little less quality and the second press is of even less quality. That is because as the wine skins are pressed, components of the skin and seeds will be merged into the juice.
If you want to make a single varietal white wine, use the free run because that is the most pure expression of the varietal. The first and second presses may be used in blends, or used when they are to be oaked or treated with a technique that alters the original flavor.
The juice is refrigerated for 1 to 2 days. The refrigeration prohibits the activation of the natural yeast. During this chilling period miniscule solids in the wine precipitate and sink to the bottom of the tank. Wines that forgo this step end up with tartaric acid crystals in the final product. (That is why sometimes it looks like there are crystals in the bottom of your wine glass). The refrigeration process is one of the characteristics that distinguishes the white wine from the red.
- The French came up with a nifty idea to take the precipitated tartaric acids and find a way to sell them. You may be more familiar with the form used in baking called “cream of tartar.”
The juice is racked into the fermenting tank (with the precipitate left behind). The fermentation begins. Typically fermentation of white wine is done in a controlled and chilled environment. The temperature of the fermentation affects the enzymes created by the yeast. The enzymes affect the flavor as they convert sugar into alcohol and carbon dioxide.
When the fermentation is complete, white wine is either bottled or aged by means of sur lie, malolactic fermentation or barrel.
- The barrel aged wines have added body and flavor. Barrels allow micro oxygenation, a slow and controlled exposure to oxygen, that creates a golden color and calms some of the acidic tones. Barrels provide a tannin as well as a flavor profile of vanilla, cedar, or baking spices.
- Sur Lie aging is a process in which the wine is aged with the yeast cells. The yeast acts as an antioxidant keeping the wine stable during this period. Sur lie aging will add flavors of bread, malted barley, white flowers, or almonds.
- Malolactic fermentation sometimes happens simultaneous to the primary fermentation or sometimes after. This is a bacterial fermentation that converts tart malic acids into softer lactic acids. When we taste malic acid in grape we associate it with flavors of green apples. Lactic acids are perceived more like cream or other dairy products.
Once bottled , white wine should be consumed within two years. Of course there are exceptions. White wines with high acid content may be aged for many years. There are some great examples of aged white wines in Germany and parts of France.
Red wine
Red wine making starts in a similar manner. The grapes are sorted. Typically the stems are removed. Most of the time the grape stems are removed because they also contain a tannin that would make the wine too abrasive. There are examples of quality wines in the world that use the stem with the intention of adding structure to the wine.
The grapes are crushed. Red wine is fermented with juice and the solids together. This Mixing of juice and solids is called “Maceration.” This is where red wine gets the color, tannin, and based on level of extraction, the flavor profile. The process is like steeping a tea bag. The more you move the solids around in the liquid, the greater the extraction. The juice sits in the tank with the layer of solids on top called the cap. The cap must be mixed around in the juice to mimic the tea bag concept. This is done using Push-downs and pump-overs. A large paddle is used to “push down” the cap to mix it, or alternatively the juice is “pumped over’ the cap to mix it together. I’ve seen this done in large production facilities with large mechanic paddles, I’ve also see this happen on smaller scales with people standing on a bridge made from a piece of wood to mix the cap into the juice.
The length of maceration depends based on the decisions of the wine maker. A short maceration period of 24 hours would produce a light rosé. A two week maceration would produce a dark red wine. The length of maceration determines the level of the color, tannin, and flavor extracted from the grape skin. Some traditional winemakers allow for longer maceration periods while other large commercial winemakers call for the quickest path to the market.
Fermentation of red wine is allowed to happen without a controlled temperature environment. Red wine has so many acids and tannins naturally occurring that the enzymes of the yeast have little effect on the flavor profile.
Red wine is nearly always barrel aged. Barrel aging:
- adds tannin from the wood
- allows for malolactic fermentation – The malolactic fermentation has little effect on the flavor of red wine, but it does soften the texture
- provides for microxygenation, gently maturing the wine
- adds the vanilla and baking spice flavors
Red wines will sit in barrels for 2,3,4 or more years based upon the wine laws governing the region and the decisions of the wine maker.
From the barrel the wine goes into bottles. It is up to the wine laws and the wine maker how long the wine will bottle age before going to the market.
Most wines you purchase are ready to drink. Can they be aged longer? Some of them, yes. 90 percent of wine you are buy are ready to drank. That’s the easiest way for the producer to make money! They are not expecting you to buy a bottle to save for 5 years before drinking.
I will have more articles digging deeper into the aging of wine as well as those wine making processes that diverge from the processes I laid out here.
Dennis Kirscher
June 28, 2021 at 3:59 am
Very informative, and an easy read. I now know where Free Run winery in SW Michigan got it’s name! Through my exposure to the wineries and vineyards in SW Michigan, I have become interested in wine making and growing grapes. I have a (very) small start up vineyard of 31 plants at our church. Started all of the vines from dead cuttings from Domaine Berrien Cellars also in SW Michigan.