Chapter : Wine making Process

Wine is an alcoholic beverage produced through the partial or total fermentation of grapes. Other fruits and plants, such as berries, apples, cherries, dandelions, elder-berries, palm, and rice can also be fermented. Grapes belong to the botanical family vitaceae, of which there are many species. The species that are most widely used in wine production are Vitis labrusca and, especially, Vitis vinifera, which has long been the most widely used wine grape throughout the world.

The theory that wine was discovered by accident is most likely correct because wine grapes contain all the necessary ingredients for wine, including pulp, juice, and seeds that possess all the acids, sugars, tannins, minerals, and vitamins that are found in wine. As a natural process, the frosty-looking skin of the grape, called "bloom," catches the airborne yeast and enzymes that ferment the juice of the grape into wine. The cultivation of wine grapes for the production of wine is called "viticulture." Harvested during the fall, wine grapes may range in color from pale yellow to hearty green to ruby red.

Winemaking, or vinification, is the production of wine, starting with selection of the grapes and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruit or non-toxic plant material. Mead is a wine that is made with honey being the primary ingredient after water. Winemaking can be divided into two general categories: still wine production (without carbonation) and sparkling wine production (with carbonation). The most widespread and recognized example of a sparkling wine is the champagne. In other regions, a sparkling wine is called Asti in Italy, Cava in Spain, and Cap Classique in South Africa. The science of wine and winemaking is known as oenology.

The process of winemaking begins with the grapes. Wine grapes are varieties of the species Vitis vinifera, slightly smaller than grapes sold in the supermarket and covered in a beautiful dark purple skin. These grapes prefer warm days and cool nights, and certainly do not grow effectively anywhere in the world. They must be located relatively close to the equator, but not too close. For red wine, grapes are processed along with their skins, and for white wine, the skins are removed beforehand.

Harvesting: Harvest time is the defining moment in the winemaking process. Grapes are harvested during the cool morning hours and moved to the winery in open bins. All of the grapes are harvested by hand to ensure that only the best grapes arrive at the winery. However, many wineries use machines to expedite the harvest process. Grapes for wine production aren't harvested until late September or early October, the ideal time for desired sugar and acid levels.

Pressing: Pressing is a process of separating juice from the grapes and their skin. Grapes are gradually mashed out. Then the total amount of juice is immediately separated and ready for vinification. This day, a lot of winemakers apply pressure to increase and determine the amount of tannin extracted from the juice. Pressed juices or wines are generally lower in acid compared to the free-run juice.

Pigeage: This refers to a local French term for traditional process or stomping grapes in an open area or fermentation tanks. Grapes are crushed to the surface and carbon dioxide gases are released. Layer of skins and other solids from grapes are called caps. Caps are the best source of tannins. Traditionally, the caps are mixed into the juice each day by stomping it through the vat.

Crushing: Once harvested, grapes are flattened. In a winery, grapes are harvested en masse, either by hand or machine, then chopped or crushed into a mush before further processing. In the old days, grapes used to be thrown into a large wooden tub and crushed by the feet of maidens. Nowadays, we use various methods, one of the most common of which is a large screw that presses the grapes against an angled wooden board. The screw grinds the grapes into a pulp, which falls down the incline into a collector.

The next step of winemaking is breaking down this mush, which is called wine must, and preparing it for fermentation. Sulfites are added to protect the must from hostile microorganisms. The beneficial microorganism, yeast, which conducts the process of fermentation, is added next, along with a few specialized nutrients and a lot of sugar for the yeast to eat. Sometimes a bit of tannic acid is added to give the wine that special "bite." Dilution or the addition of other acids is necessary to modulate the pH of the must and ensure it is optimal for fermentation and subsequent consumption. Tap water is added to provide a base for the must.

Primary Fermentation: After all the ingredients are in place, the primary fermentation begins. The must is heated to 70°F - 75°F (21°C - 24°C) in an open container and left to ferment for several days to just over a week. Depending on what kind of wine is being made, fermentation usually takes between one to two weeks. These conditions are ideal for the yeast to grow and eat. The yeast consumes the sucrose, or sugar, breaking it down along with the larger carbohydrate molecules in the grapes. Yeast changes nearly all of the sugar content in the grape sap into crisp ethanol or alcohol. Fermentation is a bubbly, foamy, biological process, the turning loose of microorganisms into the must. Special strains of wine yeast are used, because the wrong yeast or a different microorganism will not turn the must into wine, but produce an undrinkable microbial soup.

Secondary Fermentation: After this initial fermentation, the secondary fermentation begins. The juice is moved to containers in preparation for the next stage. It is in this stage that grape sugar is gradually changed into alcohol and the wine becomes transparent. Liquid matter and some sediment is skimmed off the surface of the solid matter and transferred to another container, where it is sealed off from the air. This is another phase of fermentation, called the anaerobic phase, which is necessary for alcohol to be produced. This phase takes several weeks, with the wine repeatedly being transferred from vessel to vessel in an effort to isolate the liquid wine from the solid matter. The process takes place at a lower temperature than the primary fermentation, and therefore takes significantly longer.

Ageing: After several weeks of fermentation, the wine is transferred or "racked" into a different vessel. In some instances, the wine is aged in stainless steel tanks. Some wines are set aside to age in oak barrels prior to bottling giving it the additional savor. Still other wines are bottled right away. After barrel ageing and prior to bottling, the wines are fined and filtered to help stabilize and clarify them. In a very important process called riddling, yeast sediments gradually settle to the neck of the bottle. Traditionally, a remueur, or riddler, rotates each bottle in the rack every day to tap the sediments down. Today, riddling is performed by giant machines that systematically rotate hundreds of bottles to a vertical position at once.

Bottling: This is the last stage before the slow and relatively lengthy ageing process. Wines are bottled in a sterile environment, and sealed with a cork. Wine must be slightly aged to be drinkable - white wine must sit for half a year and red wine for a full year. Some of the most famous wines are aged for multiple years in oak barrels or glass bottles, but if wine is aged for too long, it turns into vinegar.

Cold and heat stabilization: It is a process used in reducing tartrate crystals, commonly known as potassium bitartrate typically seen in wines. Tartrate crystals are similar to clear sand or grains or wine crystals. Cold and heat stabilization is next in wine making process. Unstable proteins are removed and tartrate crystals (or potassium bitartrate) frequently found in wine is reduced. After the stabilization process, secondary fermentation and bulk aging come next. This is then continued by laboratory tests as well as blending and fining. Preservatives application, filtration, and bottling process come last.

The name of a wine almost invariably is derived from one of three sources: the name of the principal grape from which it was made, the geographical area from which it comes, or—in the case of the traditionally finest wines—from a particular vineyard or parcel of soil. The year in which a wine is made is only printed on bottles that have aged for two or more years; those aged less are not considered worthy of a date. Wine years are known as "vintages" or "vintage years." While certain wines are considered good or bad depending on the year they were produced, this can vary by locality.

Winemaking is a process roughly as old as the brewing of beer or the baking of bread. In the modern world, winemaking supports many economies, such as those of Australia and New Zealand, Chile and Argentina, France, Spain, Italy, and the USA - especially California. A person who participates in winemaking is called a winemaker. A producer or merchant of wine is called a vinter, and may play little part in the actual "dirty work" of processing grapes into wine.

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Basic Course on Wine Tourism

Chapter : Wine making Process