Winemaking at a glance

Have you stopped to think what wine is?

Wine is nothing more than fermented grape juice. In theory, many fruits can make wine –blackberry or raspberry wines, for instance. In practice, grapes make the best wines and 99% of wines produced started in the grapevine.

Making wine is simple

  1. Get large quantities of ripe grapes –you can grow your own or buy them.
  2. Crush them to release the juice –this is the previous feet stomping task.
  3. Place the juice in a clean container –no leaks, please.
  4. Wait until the fermentation is finished and sugar has turned into alcohol.

Sugar turns into alcohol because of yeast. These micro-organism live in the vineyards and they are on the grape skins. Yeast gets in contact with the sugar in the juice once the grapes are crushed and begin the fermentation process, slowly converting the sugar into alcohol –and carbon dioxide, but this one evaporates into the air.

Fermentation completed, no sugar, no grape juice, you’ll have only wine in the container.

Pretty easy, isn’t it? Fermentation is a natural process and it does not look like we have much control about it. Then, why so much talk about wine and winemaking?

The buzz about wine

The wide variety of wines produced comes as a result of small variations in this process.

  • The grapes – grape juice, known as must, is the raw material for wine and two different grape varieties don’t make the same wine. Don’t forget that riper, sweeter grapes make wines with more alcohol, so where the grape grew, or harvest time, influence the final product.
  • The container – the type or size of the container can change noticeably the way the wine tastes. Stainless steel and oak are the preferred materials.
  • Temperature – the temperature the must has kept during the fermentation process has an impact in the final wine. Modern winemaking may use colder temperatures than previously thought possible.

Once fermentation is done, the final product is young material, many times rough and not worth talking about. Winemakers can do some extra things to this wine before declaring it ready to drink.

  • Maturing the wine – many wines benefit from some rest to soften and enhance its flavors. Other after-fermentation processes, apart from aging, may change a wine: clarification, blending; even a secondary fermentation – malolactic fermentation.

Modern winemaking

Viticulture, the process of growing wine grapes, has been raised from ancient art to a complex combination of science and art. Add in all the other special knowledge and skills required to produce the end product —bottled wine— and you have a Herculean (or is that Dionysian?) task.

Vintners, makers of wine, have to consider site, season, soil and a host of other factors in order to deliver fine wine to the consumer's table.

Dark soils absorb heat more efficiently and rocky soils allow better drainage and provide stones that also help retain heat. Relative concentrations of nitrogen and other elements play an essential part. Topography (the contours of land) partly determine the usable amounts of sunlight and shade, while climate encompasses temperature range, total sunlight available, annual rainfall, wind and so forth.

Which grapes are selected to be grown depend on the terroir. A 'terroir' is a group of vineyards (or even vines) from the same region that share similar soil type, weather conditions and other attributes. Planting time varies from late March to early April, with harvest ranging from late September to early October, depending on location, species and individual judgment.

Once harvested, usually by hand, the grapes are off to the crusher to be turned into must - skin, meat, and juice created in large vats containing a perforated, rotating drum. The holes allow juice and skins to pass through, but filter out stems.

Red-grape must is then sent to fermentation tanks, while white goes first to a wine press. The press is a large, usually stainless-steel cylindrical tank with an inflatable rubber bladder inside. The bladder is used to squeeze the skins against the tank walls to separate them from the juice. The result is sent to another fermentation tank.

Airtight fermentation tanks, holding anywhere from 1,500-3,000 gallons are cooled to around 40°F (4°C) and the vintner adds sugar and yeast to initiate the process. The yeast interacts with the glucose in the must through diffusion and a process called glycolysis occurs which produces other sugars and alcohol. This takes roughly 2-4 weeks, during which the vintner samples and measures the mixture.

Once fermentation is complete, red wines are sent to a press to filter the skins from what is now wine, then filtered again to remove the yeast. Some reds undergo a second, malolactic, fermentation process. White wines, by contrast, are allowed to settle, after which the yeast is filtered out.

With the yeast removed, the wines are stored in stainless steel tanks or oak barrels for anywhere between three months and three years.

After sufficient aging, where 'sufficient' is determined by individual judgment based on repeated taste and other tests, the wine is pumped from the tanks to a bottling machine. Most vineyards now have a highly automated bottling process, though even there labeling, foil addition, and stacking is often still done by hand.

Despite the many modern improvements to the winemaking process, most growers and winemakers still take a personal and passionate interest in selecting and tending vines, creating delicious varieties, and judging whether product meets their high standards. It's easy to taste the results.