Enoteca Italiana

From grapes to wine

Wine is the exclusive product of the fermentation of fresh grapes or the fermentation of the juice of fresh grapes. It is a natural beverage made from grapes. The fruit is first pressed or crushed. The juice is then fermented with or without the pomace, that is, the solid parts of the cluster. Grapes are an invaluable food product; in addition to water, they contain sugars, acids, mineral salts and other substances. Their skins hold coloring substances, aromas and tannins. Alcoholic fermentation is the engine powering the transformation of the grape juice. How does this happen? There are organic substances called enzymes that transform the sugars contained in the must into alcohol and carbon dioxide. The enzymes cultivated in the laboratory are described as "selected," while those present in the skins are described as "natural." However, even the other, selected enzymes are in fact natural, that is, they are not obtained artificially and are added to the must to aid fermentation and the production of fine quality wines. Alcoholic fermentation can be followed by malolactic fermentation, which transforms the malic acid into the softer lactic acid, softening the wine. At the harvest, the grape should possess a determined ratio between acidity and sugar concentration depending upon the type of wine that the maker wishes to obtain. For example, the elevated presence of sugar (extremely ripe grapes) will produce a wine characterized by a substantial level of alcohol with a solid body. On the other hand, pronounced acidity (relatively unripe grapes) results in a fresh product that should be drunk in its youth. However, with respect to the type of wine that should be produced, the grapes are harvested more or less ripe. The wine's color is provided by the degree of exposure to the skins and other parts during vinification. The pulp of all types of grape (including those with red or black skins) is uncolored. Different vinification processes are used depending on the type of wine desired (white, red or rosé).

Vinification off the skins
In the vinification off the skins method, the pressed juice is immediately raked into stainless steel containers (to obtain a fresh wine to be drunk in its youth) or into wood (if a more complex and long-lived wine is desired). Then the must is fermented alone, with all solid parts removed. Fermentation is usually initiated with select yeasts.

Vinification on the skins
Having been harvested and brought to the winery, the grapes are usually (but not necessarily) removed from the stalks with the use of suitable equipment, either before or during pressing. The extracted must ferments on the skins. The high temperature reached by the mass generates "tumultuous fermentation," called so because the wine seems to boil. The heat aids the passage of the polyphenolic substances from the skins. Consequently, after a few days, the must takes on color and is enriched with anthocyanins and tannins from the skins. To secure long-lived red wines with big structures and personalities, maceration (alcoholic fermentation with the skins) is prolonged for more than two weeks.

Vinification partly on the skins
After being crushed, the grape juice remains in contact with the skins, exactly as in fermentation on the skins but only for an extremely brief time. Once the desired color has been produced, the must is removed from the pomace and fermentation continues as in vinification off the skins.

Special wines
In addition to whites, reds and rosés, there are wines that are described as "special,"meaning their vinification is more complex than those discussed above. These are wines to which are added sugars, musts, alcohol or herbs during the course of production.
What are they? Sparkling wines (spumanti), raisin wines (passiti), liqueur wines (liquorosi) and flavored wines (aromatizzati). Sparkling wine can be produced according to the Classic Method (in France, the “Métode Champenoise”), which uses varieties of Chardonnay, Pinot Nero and, to a lesser extent, Pinot Bianco and Pinot Grigio. The Charmat/Martinotti Method can be adopted, theoretically, for any variety, whether aromatic or semi-aromatic, like Moscato, Brachetto, Prosecco and others. Classic Method sparkling wine can be produced from white or red grapes, or both. Production begins with a wine base, often obtained through the assemblage or blending of different batches (la cuvée). During bottling, the wine-maker adds a mixture of yeasts and sugars, the so-called “liqueur de tirage,” before corking the bottle. Yeasts permits production of sparkling wines by means of natural fermentation, different from industrial beverages in which the bubbles are obtained with the addition of pressurized carbon dioxide. The bottles are laid down, stacked and left for a time (that can last many years) at constant temperatures (11-13° C, or 52-55° F.). During this period, the wine develops its foam (presa di spuma) from the yeasts, which transform the sugars into carbon dioxide and, in the process, create six levels of pressure within the bottle. Once the second fermentation has been completed, the wine is left on its deposits, which give the wine greater aromatic fullness. Afterward, the bottles are inserted in special racks resembling sawhorses (pupitres), where the process of the remuage occurs. The bottle is moved every other day with a small rotation (an eighth of a turn around its own axis) and inclined vertically. After about 40 days, the bottles will point directly downward so that the sediment formed by the wine collects on the cork. This procedure, once done by hand, is increasingly performed with the aid of suitable equipment. The corks are withdrawn in order to remove the deposit, and the bottles are then topped off with other wine mixed with sugar. The wine is then definitively corked.
The Metodo Charmat/Martinotti Spumenti is produced with a base consisting of wine subjected to a secondary fermentation carried out in a large stainless steel tank, called an autoclave. The tank is hermetically sealed, then sugar and yeasts are added. Once it has developed foam and become a sparkling wine, the wine is bottled cold. In general, sparkling wines made by the Classic Method have a great equilibrium. They can possess scents of bread crust and are consumed some years after the harvest.
Sparkling wines produced in an autoclave are generally fresh and fruity and best consumed in their youth.
Raisin, liqueur and flavored wines can be sweet or dry, pungent and of moderate endurance, alcoholic or complex with rich aromas and flavors, long endurance and a high level of alcohol. In reality, the Passiti are not really special wines but instead require a special technology that enables them to develop high levels of alcohol. To produce a wine with a great deal of alcohol, the grapes must be dried in such a way that the percentage of sugars they contain is extremely high. Drying can be performed with different techniques: late harvesting, drying on the vine or forced drying. Sometimes the grapes are covered with Botrytis cinerea, a particular mould that is also known as noble rot, which dehydrates the grapes, concentrating the sugars without degenerating them.
Forced drying is effected after the grape harvest. The grapes are laid out on mats placed on the ground. The clusters are well exposed to the sun, placed on grates or hung up in warm and airy rooms known as "fruttai." Drying not only makes the grapes sugary, but also fruity, with greater aromas and richer extracts.
Liqueur wines are characterized by the effects of the action of flor yeasts, which form a veil or film on their surfaces that protects the wine from oxygen and gives it a special, distinct bouquet. Otherwise, alcohol or must is added for more or less prolonged periods in casks that are not fully filled up, or in bottles. Such wines as Marsala, Port or Sherry can be dry, sweetish or sweet.
Flavored wines, like Vermouth, may contain alcohol, sugar, extracts or infusions of bitter/aromatic spices and herbs.