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Background

Usually, wine is made of grapes, but it can also be made from flowers, other fruit, and plants. Apples, cherries, dandelions, elder-berries, palm, and rice can also be fermented.

Grapes belong to the botanical family Vitaceae, which has many species. The species most often used for wine production are Vitus labrusca and, in particular, Vitus vinifera, the most widely used wine grape worldwide.

Wine has long been assumed an accidental discovery, as grapes contain all ingredients for making wine – including pulp, juice, and seeds which contain all the acids, sugars, tannins, minerals and vitamins required to make wine. The naturally frosty-looking grape skin (called “bloom”) catches the airborne yeasts and enzymes that ferment juice into wine.

The cultivation of grapes for the making of wine is called “viticulture.” Grapes are harvested in the fall. The colours of the grapes vary from pale green to hearty ruby red.

Wines are characterized by their colour – white, pink or rose, and red, and is broken down into four broad categories.

1. table wines include white, rose, and red
2. sparkling wines include Champagne, and other effervescent (“bubbly”) wines
3. aromatic wines are made from flowers, fruits, and plants
4. fortified wines are table wines with brandy or other alcohol added

The name of a wine is derived from one of three sources:

1. the name of the principle grape used to make the wine
2. its geographic area
3. or – in the case for the finest traditional wines – the name of a specific vineyard or tract of soil

A year is only printed on a bottle if it is two or more years old. Wine younger than that isn’t thought worthy of a date. Wine years are called “vintage years,” or “vintages.” White or rose are aged one to four years – they do not improve over time, unlike red wines, which are aged 7 to 10 years. Older wines are more expensive because the quality of the wine is improved by age. Also influencing price are the actual grapes, when they are picked, proper care of the grapes, the fermentation process, as well as other factors.

The most common bottle sizes are the half-bottle, the imperial pint, the standard bottle, the gallon bottle or jug. To keep light from aging the wine while its on the market, red and rose wine bottles are dark-coloured.

Wine Production

As mentioned previously, the grape contains all necessary ingredients to produce wine: pulp, juice, sugars, acids, tannins, and minerals. Some winemakers (vintners) add yeast to make the wine stronger, and cane or beet sugar to increase alcohol content. Sulphur dioxide is usually added during fermentation to control the growth of wild yeasts.

The Manufacturing Process

While the process of wine making hasn’t changed much, modern technology has streamlined and increased output. These advances include mechanical harvesters, grape crushers, temperature-controlled tanks, and centrifuges. The type of grape and the amount of wine to be produced determines the method involved.

Some recipes require the vintner to monitor and regulate the amount of yeast, the fermentation process, and other steps in the production.

Timing is the universal factor in making wine. The timing of grape picking, removing the must, monitoring and regulating fermentation, and storing the wine long enough.
There are four steps in the wine-making process:

1. harvesting and crushing the grapes
2. fermenting must
3. ageing the wine
4. packaging

Harvesting and Crushing the Grapes

A refractometer is used to determine if the grapes are ready to be picked. It is a small hand-held device that allows vineyardists to accurately establish sugar levels. If the grapes are ready for picking, a mechanical harvester gathers and funnels the grapes into a field hopper, or mobile storage unit.

Mechanical harvesters were introduced in California in 1968. They are used in medium to large vineyards, eliminates the need for handpicking. Some vineyards use mechanical harvesters that have a grape crusher mounted on it, allowing them to harvest and crush at the same time. This eliminates the need to have the fresh grapes (“must”) crushed at the winery. It also prevents oxidization of the juice through tears in the skins.

Next the field hoppers are taken to the winery and unloaded into a crusher-stemmer machine.

Crusher-stemmer machines can be either hydraulic or driven by air-pressure. The grapes are crushed and the stems removed, and the liquid must which remains flows either into a stainless steel fermentation tank or a wooden vat (for fine wines).

Fermenting the Must

White wine: all grape skins are separated from the must by filters or centrifuges before the must is fermented.
Red wine: the whole crushed grape, including the skin, is put in the fermentation tank or vat. The colour in red wine is derived from the skin. The colour (light or dark) is determined by the amount of time the skins are left in the vat. For rose wine, the skins are left in the vat for only a short period of time.

During the fermentation process, wild yeast are added to the fermentation tank or vat to turn the sugar in the must in to alcohol. Different levels of yeast are added to increase the strength of the wine. Also, cane or beet sugar may be added to increase the alcoholic content. Adding sugar is called chaptalization. Usually this is done if the grapes didn’t get enough sun before harvesting. A handheld hydrometer is used to determine the sugar content in the tank or vat. Depending on the wine being produced, the wine must ferment for about seven to fourteen days.

Ageing the Wine

Wine must be stored, filtered, and properly aged, once crushed and fermented. Sometimes, the wine must also be blended with other alcohol. Damp, subterranean wine cellars are still used by many wineries to keep the wine cool, but some wineries use epoxy lined and stainless steel tanks. The tanks are temperature-regulated by water circulating inside the tank shell’s lining. Similar tanks are used instead of redwood and concrete vats when wine is temporarily stored during the settling process.

After fermentation, some wines (mainly red wines) will be crushed again and pumped into a second fermentation tank for another three to seven days. This not only extends the wine’s shelf-life, but it ensures its colour stability and clarity.

Next, certain wins are pumped into settling (“racking”) tanks. The wine remains there for one to two months. Typically, red wine is racked at 50 to 60 degrees Fahrenheit (10 to 16 degrees Celsius), and white wine is racked at 32 degrees Fahrenheit (0 degrees Celsius). Following this process, the wine is then pumped into another settling tank for another two to three months. Here any further unwanted weighty debris (remaining stem pieces, leaves, etc.) settle to the bottom of the tank. This debris is eliminated when the wine is pumped into another tank. Smoother wine is produced because of the settling process. Some wines require further settling.

After racking, the wine passes through a number of filters or centrifuges where the wine is stored at low temperatures or where clarifying substances flow through the wine. After various filtering stages, the wine is aged in stainless steel or wooden vats. Rose or white wine age for one to four years, or far less than a year. Red wines may age f or seven to ten years. Stainless steel above-ground vats are used my larger wineries, while more traditional wooden vats, stored in damp wine cellars, are used by smaller wineries. The wine is now filtered one last time to remove any unwanted sediment. It is now ready to be bottled, sealed, crated, labeled, and shipped to distributors.

Packaging

Automated bottling machines are now used by most medium to large wineries, and most reasonably priced and expensive wines have corks made of a special oak. Peel-off aluminum foil or a plastic seal are used to cover the corks. Cheaper wines have an aluminum twist-off cap, or plastic stopper. The corks and screw caps keep the wine from being spoiled by the air.
Wine is usually shipped in wooden crates, but cheaper wines may be packaged in cardboard.