How is wine made?

Wine is a living thing. It is made, not only of grapes and yeast, but of skill and patience. “When drinking wine, it remember that to the making of that wine has gone, not only the labor and care of yeast, but also experience of centuries”. Viticulture refers to the decisions made and procedures performed in the winery that help shape the flavors, quality, and characteristics of wines. The path that winemaking takes can be divided into six distinct stages: the harvest, grape processing, fermentation, bulk aging, clarification and conditioning, and bottle aging.

Although often considering part of viticulture of grape growing, the harvest is also where viniculture begins. Technically, the harvest involves picking the grapes for a particular wine or from a particular vineyard when they are ripe, considering how many of wines characteristics are dependent upon the ripeness of the grape used.

Once the optimum ripeness has been achieved in the vineyard, the true work of the harvest begins. The grape must be picked from the wines and be transported to the winery for the wine making process to continue. With the way those grapes are to be picked, though can also have an immense ramification on a finished wine.

There are two basic methods of harvesting grapes: hand harvesting and mechanical harvesting. Hand harvesting consists of workers moving through a vineyard and picking bunches of grapes, which are then graded, sorted, and sent to the winery. If quality is the ultimate goal of a winemaker, then hand harvesting is the best method to employ. Hand harvesting involves using people with eye and brains, moving though the vineyard to pick grapes. Therefore they can make decisions what to pick and what not to pick, ensuring that only those grapes that are ready to be picked are cut from the wines.

Some of the vineyards responsible for extremely high-quality wines can be harvested more then once (in some cases vineyards can be harvested nine or ten separate times), in which case only perfect grapes are selected to be picked each time. Hand harvesting has its drawbacks, those workers going to a vineyard need to be paid for their services, and a slow, methodical harvest is not very efficient. If efficiency is the goal   (for instance, large commercial wineries that have a necessity to harvest faster) then the hand harvesting may not be practical.

A mechanical harvest is one in which a piece of farming equipment is used to remove the grapes from vines. This is typically done with a modified tractor that has arms that reach out and grab the wines, shaking them and causing the grapes on the vine to fall to the ground. However, there are major drawbacks to this method – damaged or bruised fruit, and gathering unripe and rotten grape bunches as well as sticks, rocks, and other matter. Nevertheless, it is very fast and efficient, and involves much less labor and money then hand harvesting. Regardless of the method used, though once the harvest has been completed the grapes are taken to the winery, and the next stage of winemaking process begins, the crush.

Crushing usually consists of gently breaking the skin of the grapes to release their juices on a piece of equipment called a crusher. The resulting mixture of grape juice and grape solids (such as the skins, stems, seeds, and pulp) is referred to as must. Great care is usually taken at this point to avoid excessive oxidation, which could degrade the quality of the must. Regardless, most winemakers’ work quickly to process the grapes into must and then begin fermentation.

Pressing is usually conducted in either a basket press or a bladder press. The process of pressing for the white wines involves removing the grape juice form the solid matter: skins, stems, seeds, and pulp. In fact, skins must be removed before fermentation for white wines to limit the amount of tannins, bitter flavor compounds, and pigments that can be extracted into a juice. On the other hand, when producing a red wine a winemaker has to use black-skinned grape and the only place where grapes contain pigment is in their skins and without these dark-colored skins, it would be impossible to make a red wine. Therefore, the primary difference between the production of white wines and red wines is that red wines are fermented with skin contact and white wines are fermented without.

Fermentation itself is one of the most important aspects of winemaking process, it is what converts grape juice into wine. One of the biggest decisions a winemaker needs to make about the fermentation process is how it should occur. Wild yeast clings to the skins of wine grapes as they grow, and this yeast can be used to ferment the wine. However, many winemakers choose instead to use cultured yeast purchased from a laboratory to conduct their fermentations. The reasons are flavor and potential lack of enough yeast cells to quickly begin fermentation.  It’s crucial to remember that the only ingredient used to produce wine other then grape juice is yeast, so this can be extremely important. Mostly wild yeast is more widely used in Europe, where thousands of years of winemaking tradition have led to the identification of beneficial yeast strains.

Outside of Europe, a lack of tradition and a focus on technology and science lead to the heavier use of cultures yeast. Another essential decision a winemaker should determine is the temperature at which fermentation will be conducted, because even a few degrees difference can have major impacts on the flavor and characteristics of a finished wine. Besides that, warm fermentations are often conducted quickly lasting only a week or two. Cool fermentation progresses more slowly, lasting from two weeks to a month or more. The final major decision a winemaker needs to make is the type of material in which a wine will be fermented. Most wine goes through fermentation in stainless-steel vessels because they are easy to clean and sanitize after use, will not react with the wine during fermentation and are ideal for temperature control.

Consequently, after the fermentation has concluded, a winemaker has technically produced a wine. Nevertheless, the wine is only at the beginning of the winemaking process; and it has to wait several months or years before it is finished and ready to drink. During this time the wine will go though stage of bulk aging. Aging in bulk allows winemaker to have access to the wine so that all manner of different winemaking practices can be employed, and it allows the forming of sediment and to be clarified.

One of the major influences a winemaker can have on the flavor and characteristics of a wine is choosing the type of material the wine is aged in during the bulk aging stag. The two most important categories of materials used for bulk aging are nonreactive and reactive. A nonreactive material will not interact with a wine it comes in contact with. It will remain completely neutral, not adding any flavors or aromas. The most common nonreactive material used in wineries for bulk aging is stainless steel, although some winemakers use glass-lined tanks, concrete vats or sometimes even wood barrels lined with paraffin wax or other neutral sealant. A reactive material, on the other hand, will interact with and react to wine it comes in contact with. It can change the aromas, flavors, and even color of the wine. The most common reactive material used in wineries for bulk aging is wood, usually in the form of oak barrels.

Conditioning, clarifications and blending process are the practices a winemaker has the most control over, and can significantly shape the characteristics and flavors of a finished wine. The conditioning stage of the winemaking process involves manipulating a wine’s characteristics though physical, chemical and biological means. Several different techniques can be utilized, with the ultimate goal of accentuating certain characteristics and diminishing others. Many European winemakers limit these practices (or they are limited by law) because they strive to show off what the land can produce more than their skills in winemaking. The important conditioning practices are: Acidification, Sur Lie Aging/aging on the Lees, battonage, Malolactic Fermentation.

Regardless of what causes wines to be hazy or cloudy the winemaker must address clarity, and several methods are used to clarify wine. During clarification, the winemaker will attempt to use the gentlest means possible, which can also strip flavor out of a wine if too aggressively employed. The major methods of clarification are: racking, fining, and filtering. Additionally, winemaking often involves blending multiple components together into one finished wine. Most blending is conducted just prior to bottling; and can be used to balance certain characteristics in a wine, to add complexity or to maintain a consistent style over the time.

 Once the stages of bulk aging, blending, clarification and conditioning practices have been finished the wine is bottled. Bottles are purged with an inert gas to expel oxygen, filled with wine to an exact level, sealed a with cork and labeled. Nevertheless, the wine must still go through the final stage of the winemaking process: bottle aging. When bottled, the wine contains a small amount of dissolved oxygen. This oxygen will slowly interact with and oxidize the wine over time, mellowing and maturing it, while other components in the wine also interact with one another. The time it takes for a wine to reach its peak once is bottled can vary widely. Some wines require decades in a bottle to reach maturity, while others require only a short period of a couple of months or less. This is a winemaker decision that can have a major impact on the quality of wine when it is actually consumed.  Once the bottle aging is complete the wines are packed in cardboard boxes or wooden case. They are often sold to distributors and then to retailers, where they are finally purchased by the consumer, and at long last the journey from grapes to glass is over.