As you pull the cork from your favorite bottle of wine, have you ever thought about how the stuff is made? Why it has the taste it does, where it got its brilliant color, how mashed fruit turned into alcohol? Winemaking is one of the oldest, most pervasive and popular of human activities. To make what is essentially high-octane grape juice is pretty easy; making it taste good, however, is a good bit more difficult. It requires the right grape, growing in the right soil, in the right weather.
What is Wine?
The answer to this basic question is that wine is fermented grape juice, but with a few extra twists. Fortunately for mankind, it was found early on that if you leave any fruit containing sugar alone for a while it will turn into booze. In the fermentation process, yeast converts any sugar in the fruit into alcohol. Yeast is found naturally floating around everywhere. So if you left some grape juice sitting outside, yeast would probably eventually mix with it and ferment it into wine naturally. This is the process our ancestors used for millennia.
Over the years, it became an art rather than an accident, and today, science is becoming more a part of that art with each passing year. Inebriated, barefoot grape stompers have given way to precision machinery crafted specifically to gently extract juices without destroying the skins. The fermentation has become carefully controlled. Yet with all of the new science and technology, the basic process still comes down to producing a flavor mix that pleases the winemaker’s palate. So let’s follow some modern grapes on their journey from vine to wine.
Preparation
The first step in making a wine is to have the grapes perfectly ready to be picked. They have to be at the right stage of ripeness, and they also have to be picked at a time of day that ensures that the acids and sugars are in proper balance. They can be picked either picked by hand or machine, but they must be picked carefully to prevent bruising. They are then placed on a table for sorting, and for removal of spiders, leaves and the occasional mouse (Yuuck!) before moving on in the process.
Next the grapes are run through machines that gently squeeze out the juice. Some of these devices have a mechanism that de-stems the grapes, while others require that this be done manually beforehand. And even in today’s mechanized world, foot-stomping is still sometimes used instead of a crushing machine. For white wines, the crushed grapes are strained to remove the skins, pulp, and remaining stems from the juice before being sent to the vats for fermentation. For red wines, the skins are left in during fermentation to give the initially clear juice the desired hue, and to impart the flavors and tannins wanted in reds.
Primary Fermentation
This is the step where the natural sugars of the grape are converted to alcohol through the action of cultured or native yeast. White wines are fermented at cool temperatures to extract their fresh and fruity qualities. This usually occurs in steel tanks, but some whites, mainly Chardonnays, can be oak-barrel fermented. The wood barrels impart a flavor to the wine that gives it greater richness and complexity.
During the fermentation of red wines, the release of carbon dioxide pushes the skins and seeds left in the juice upward. This creates a “cap” at the top of the vat that must be remixed with the juice beneath to achieve the final characteristics desired in the wine. The winemaker does this by either “punching down” the cap to submerge it into the juice, or by draining the juice from the bottom of the tank and pumping it back to the top to break up the cap. This is called the “rack and return” or “pump over” method. However the remixing is done, after the fermentation process is complete, the new wine is pressed off the skins and moved to vats or barrels to commence the aging process.
Aging
Aging has traditionally been done in barrels, but today stainless steel vats with oak chips along the bottom are sometimes used. Red wines normally spend more time aging in wood than do their white counterparts. Extended barrel aging for anywhere from a few months to several years gives the tannins of red wines time to soften and allows the fruitiness to emerge in response to the gradual oxidation allowed through the barrel. As with white wines, extracts from the wood itself contribute to the aroma, flavor and texture of reds. A winemaker once explained that the use of barrels was almost like having a “spice cabinet” to use in his wine recipes. The oak used in the barrels may be French, American, or of other origin; the “toast” level or amount of charring of the wood can vary; the barrels may be old or new. Different mixtures of these qualities produce differences in the wine after aging. After aging, the wine is bottled, stored, sold, saved on bars or in cellars for varying periods of time, consumed and enjoyed.
Many steps and variables have been skipped in this article for the sake of brevity. Any winemaker will tell you that the process is not nearly as simple as I have made it sound. Every year, Mother Nature hands them a different batch of grapes with different characteristics, and great artistry and experience is necessary to produce consistently quality wines. Next month, I’ll interview a winemaker to get more of a hands-on insight to the process.