Wine

Article index

		Production process of wine
		Cleaning
		Pretreatment
		Chaptalisation or acidification?
		Removing the skins
		Fermentation
		Maceration
		Melolactic fermentation
		Aging and preparation for bottling
		Clarifying
		Bottling

Wine producers are often inclined to say that the wine is already made in the vineyard. By this they mean that the flavor of the wine is already decided by the vine. However, during the process of making wine the flavor can still be influenced for a great deal. In an uncontrolled process good grapes may still give vinegar instead of wine. During the production process many parameters influence the final flavor and storage life of the wine.

Production process of wine

The production process of wine may differ by type of wine and even by season. The production process mentioned below is a standard production process with some frequent occurring extra intermediate steps. Each extra step or change of a parameter results in another type of wine. Besides that, the type of grapes is of course of major influence. Generally, more extra steps are executed in the production process of red wine.

Cleaning

After the grapes have been picked they are cleaned. Affected grapes, unripe grapes but also twigs and sand are removed. Subsequently, in most cases the stalks are removed. With some red wines the stalks are left on the grapes to give an extra flavor (by its tannin) to the wine.

Pretreatment

Sometimes blue grapes are given a whole bunch fermentation (also macéron carbonique). This fermentation makes sure that early fruity aromas are formed. The whole bunch fermentation happens in the absence of oxygen. This is done by letting the grapes ferment in a closed tank with carbonic dioxide. This fermentation is an intracellular fermentation, without adding culture to it.

After the undesirable parts are removed and after a possible intracellular fermentation the grapes are bruised and pressed. When white wine needs to be obtained the skins are removed afterwards. For red wine the skins are removed in a later phase so that they can still give color and tannin to the juice.

Chaptalisation or acidification?

The grape juice can be chaptalised or acidified. Chaptalisation means that sugar is added, which is done when the grapes do not contain much sugar of themselves. Each 18 grams of sugar in a liter of must (grape juice with the possible skins) results in 1% alcohol. In the north of Europe en in cold areas it is normal and allowed to add sugar. In the south of Europe it is prohibited, although it is allowed to add concentrated grape juice, which also results in an increase in sugar level and therefore in the alcohol level.

Acidification is the opposite of chaptalisation and is done when the must does not contain much acid. In most cases tartaric acid is added because this is least obtrusive. Apple acid or citrus acid are also used sometimes. Acidification can be done before or after the fermentation, but doing it before the fermentation gives the best mixture in the must.

Removing the skins

For a mild wine the level of tannin should not be too high. To obtain this the skins can be removed. The disadvantage, however, is that the wine has no or almost no red color. The solution is a cold soak (maceration) before the fermentation. By a cold soak of 24 hours the color of the skin is absorbed, but not much tannin is.

Fermentation

After this the fermentation can be started. During the fermentation the sugars are converted into alcohol and aromatic substances. The fermentation has to happen at a constant temperature, for white wine the temperature should be between 12 and 20ºC, for red wine between 35 and 40ºC. When fermentation happens at a too high temperature the wine looses its aroma, freshness and character. With red wine it is important that the skins and the possible stalks that surface (called the cap) are stirred in the must to advance the transfer of color and tannin. An important decision in the fermentation process is the choice for the original fermentation culture on the grapes, which may differ each season and may consists of several cultures, or the choice for adding one or more pure cultures. With this last choice the process is more constant and similar aromas are produced. Each culture advances certain aromas and puts others to the background.

Maceration

Sometimes a maceration is executed with a red wine. This is a after soak in which the cap remains on the must for a deep color and more tannin in the wine. After this possible maceration the cap is removed.

Subsequently it is possible to execute a must concentration. This is done for Bordeaux wines, but in other regions it is not much used. The concentrating of the must by means of evaporation under vacuum or by means of a reversed osmosis gives the wine a richer flavor. The effects of must concentration on the ripening aromas (in the long term) is for the time being unknown.

Melolactic fermentation

To make the wine less sour a melolactic fermentation can be executed. During this fermentation the sour tasting apple acid is converted into the more mild lactic acid. In this way the flavor of the wine is made less aggressive and feels more heavy. In white wine the fermentation gives a creamy flavor that is less fruity.

Aging and preparation for bottling

The wine is aged in barrels or tanks of stainless steal, wood, fiberglass or concrete. Storage in wood has the best effects on the flavor, but to attain this flavor it is also possible to add wood chips etc.

Clarifying

By mixing one or more types of wine of different vineyards a wine is mixed with the desired flavor. After the mixing the wine is purified and/or filtered (in case of wood chips) and/or stabilized. After this the wine is ready to be bottled.

Bottling

The wine is bottled in bottles of glass. These are closed with a cork. With high pressure the (wet) cork is pushed into the bottle. Today it is also possible to buy wine in bottles with a screw cap.