Wine. It has been made for millennia, revered for centuries, and become a global obsession over the past decades. It has inspired poets and philosophers, artists and writers, and on countless occasions, the common man. You needn't know much about wine to enjoy it; yet, as with many pursuits, understanding often leads to greater pleasure. And, at least in the context of restaurants, understanding often leads to better wine selections. Here's a little introduction to the world of wine, for anyone who happens to find themselves inspired.
Wine has been made for at least 5,000 years, although the exact origin of winemaking is unknown (it is believed to be accidental). Wine is the result of the fermentation of grape juice, during which yeast feeds off the natural sugar in the grapes, converting the sugars to alcohol. While this transformation is the basis of all wines, the wines that result from this process are quite diverse. Intricate details, such as the type(s) of grape grown, the location of the vines, the climate in which the grapes are grown, the particular weather during the growing season, the filtering of the grape skins, seeds, and stems, the containers in which fermentation takes place, and the length of fermentation all factor in to the final product. Further factors include whether the wine is filtered before bottling, how much sugar is allowed to convert to alcohol, whether additives are used to increase or decrease acidity or alcohol levels, even length of time a wine is aged before it is opened, and how it is stored. There are millions of different wines in existence today, each with its own unique footprint.
There are over 200 grape varieties grown worldwide that are used produce wine. Each grape type (varietal) lends different characteristics to a wine: color, acidity, tannins, alcohol level, aromas, and tastes. Yet the grape alone does not determine the qualities of a wine; where the grape is grown plays equal importance. The French word terroir is used to refer to the environment in which a grape is grown; the word implies a strong relationship between environment and a grape's quality. Terroir incorporates environmental features both large and small: the amount of sunlight, the temperature, the amount of rainfall but also the soil makeup, the physical features of geography, even the microorganisms in the soil. The unique combination of environmental factors surrounding any grapevine influences the character of the grapes.
This means that grapes grown in different locations will differ from one another in character. Chardonnay grapes grown in Napa, California, for example, produce an entirely different wine than Chardonnay grapes grown in Burgundy, France. Not all grapes can be grown in all areas either; like all agricultural products, grapes require a certain set of climate conditions—temperature, sunlight, moisture, altitude—to ripen to maturity. This is why some regions are known for growing certain grapes— why the best Rieslings come from the cool climates of Alsace and Germany; why good Shiraz is grown in Australia, and why Napa Valley is so fond of Cabernet Sauvignon—through trial and error vintners have found that their climate and soil are well-suited to particular varietals.
But having a good climate and location for a particular varietal does not guarantee success. Grapes grown within the same acre can differ from year to year in their quality. This is why some vintages of wine are known as better than others; the conditions during one year's growing season can be better than the last or the next. Temperature, amount of sunlight, rainfall, heat, and wind all factor into the quality of the grapes grown. Years where the conditions were favorable throughout the season will produce better quality grapes; years that saw drought or torrential rain, erratic frost or abnormal heat can result in a poorer quality crop.
Grape types are commonly divided into red and white grapes. In general, red grapes are used to produce red wines, white grapes to produce white, although some red grapes can be used to produce white wines (the skins of the grapes are simply removed early on in the fermentation process), and occasionally a white grape will be used in a red wine blend. Here are some of the most common grapes.Red Grapes
Vinification, or the process of turning grapes into wine, is responsible for many of a wine's characteristics. Like grape-growing, the wine-making process involves the same basic steps for all wines, although the details of the process can vary widely. The decisions involved in the making of wine begin with the harvesting of the grapes, which can be done either by machine or by hand. Some vineyards produce their own wine from their own grapes; others sell their grapes to wineries that will produce wine. Once grapes are harvested, they are crushed to split the skins and destemmed—it is up to the winemaker to determine what percentage of stems get removed at this stage. White wines are then pressed, to separate the grape skins and seeds from their juice, and then fermented; red wines are first fermented and then pressed (fermenting the grapes with their skins contributes to a wine's red color). After fermentation, the wine is transferred to ageing vessels, then may undergo racking, fining, filtration, or stabilization processes before it is eventually bottled. Decisions are made at every step of the way—about which equipment and processes to use, the length of time each step will take, whether to use additives, whether to skip or undertake certain steps altogether—and these decisions ultimately influence the character and quality of the wine.
The wine maker's choices determine the following about the wine:
A winemaker can opt to produce still wine, fortified wine, or sparkling wine. The majority of wines produced are still wine, which follows the basic fermentation process. Fortified wines such as sherry, port, and Madeira, have alcohol added to the wine. Sparkling wines, such as Champagne, Cava, and Prosecco, do not allow carbon dioxide—a natural by-product of fermentation—to escape the wine.
A winemaker's decisions regarding which grapes to use and when to separate the skins from the juice partly determines the wine's color. White wines have skins removed immediately after pressing, while red wines are fermented while the skins, stems, and seeds from some or all of the grapes are still intact. Rosé wines have the skins left on for just a brief amount of time.
Fermentation will naturally cease when all of the sugar in a wine is converted to alcohol (among other conditions). However a wine maker may opt to halt the fermentation process sooner, leaving some residual sugar in the wine. The decision of when to stop fermentation combined with the amount of natural sugar in the grapes determines whether a wine will be dry, off-dry, semi-sweet, or sweet.
Wines can vary from less than 8% to over 15% alcohol by volume. This percentage is largely determined by the winemaker, who may halt fermentation sooner to create low alcohol wines, or prolong it to achieve higher alcohol wines. Winemakers can also add additional sugars (known as enrichment) to be converted to alcohol, thus increasing the alcohol content of the wine.
While the natural acidity in grapes will largely determine the acidity of a wine, the wine maker can adjust or alter this acidity. Acidification and deacidification are both common in winemaking, particularly in unusually warm or cool climates. Maloactic fermentation, a second fermentation process that most red wines and some white wines go through, decreases the acidity of a wine.
Tannins are present in grape skins, stems, and seeds, as well as in oak. The wine maker's decisions regarding when to de-stem grapes, when to separate them from their skins, as well as whether and how long to age or ferment the wine in oak determines the level of tannins in the wine.
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