Wine grapes: Different cultivars and products

Wine is an alcoholic beverage produced through the fermentation of grapes or fruit. It has a long and rich history dating back thousands of years. The earliest known wine production took place around 6 000 BC in Georgia and appeared in the Balkans around 4 500 BC, from where the practice spread to ancient Greece, Thrace and Rome.

The art of winemaking

Vinification is the art of winemaking, which starts with the selection of appropriate grapes or other ingredients and culminates in the bottling of the finished wine. Most wines are made of grapes as the primary ingredient, but fruit, plants and other ingredients may also be used – for example, mead is a type of wine made with honey as the primary ingredient.

Winemaking is further classified into two general categories: Still wine production, which is wine produced without carbonation; and sparkling wine production, which is wine produced with carbonation (either natural or injected).

Read more about the best South African pinotage wines here.

Red, white and rosé

The process of making red wine differs from that of white wine in that red wine is produced from the must, or pulp, of red or black grapes. A further difference is that during red wine production, the must is fermented together with the grape skins to give the wine its colour.

White wine by contrast is produced through fermentation of the grape juice, which is obtained by crushing the grapes to extract the juice – the skins play no further part in the process. White wine can also be produced from red grapes by extracting the juice and ensuring minimal contact with the grape skins.

Rosé wines, another variation, are produced from red grapes. Here the grape juice is allowed to stay in contact with the dark grape skins just long enough to obtain a pinkish colour (called blanc de noir) or by blending red wine with white wine.

Table wine

Wine is produced through the fermentation of grapes. Fine wines are also a collector’s item and can fetch thousands of dollars per bottle. The wines, termed ‘investment wines’, are considered Veblen goods, in other words goods for which demand increases rather than decreases with a rise in their prices. The characteristics of investment wines include:

• It is proven to hold well over time.
• The period from maturity and approachability (the drinking-window plateau) extends over many years.
• There is agreement among experts as to the quality of the wine.
• Rigorous production methods apply at every stage of the winemaking process, which includes grape selection and appropriate barrel aging.

Vermouth

Vermouth is a fortified and aromatised style of wine flavoured with roots, barks, flowers, seeds, herbs and spices, and is an important ingredient in many of the first classic cocktails, including the martini, Manhattan and Negroni. It may also be consumed as an aperitif and used as a substitute for white wine in cooking.

Traditionally, vermouth was produced in sweet and dry types, although new types have been created recently, including white or bianco, amber and rose. Vermouth is produced from a base of a natural, low-alcohol white wine to which a mixture of dry ingredients is added. Grapes most often used to produce the base wine include Clairette Blanche, Piquepoul, Catarratto and Trebbiano.

The base wine is aged for a short time before the dry ingredients are added. Fortified wine is wine to which a distilled beverage has been added. It is different from spirits made from wine because spirits are produced by means of distillation, whereas fortified wine is simply wine with spirits added.

Sparkling wine

Sparkling wine is a type of wine with high levels of carbon dioxide that may be obtained through several processes:

• Through the méthode champenoise, which is through natural fermentation in the bottle.
• Through the Charmat process, which is fermentation in a large tank designed to withstand high pressure.
• Through carbon dioxide injection.

Sparkling wine is usually white or rosé wine with a sweetness that ranges from very dry brut to sweeter doux varieties. Champagne, which is the classic example of a sparkling wine, is only produced in the Champagne region of France, and most sparkling wine producing countries reserve the word for this specific wine from France. Many sparkling wines are produced elsewhere, and other countries, regions and labels include Espumante in Portugal; Cava in Spain; Franciacorta or Trentodoc in Italy; and Cap Classique in South Africa.

Port wine

Port is a type of Portuguese fortified wine made exclusively in the Douro Valley in the northern province of Portugal. Port is produced in several styles:

• Tawny port: This style of port is made from red grapes and is aged in wooden barrels, where they are gradually exposed to oxidation and evaporation. As a result of this process, tawny port gradually mellows to a golden-brown colour and the oxidisation gives the wine a nutty flavour. Age is a very important factor with tawny port: Without an indication of age, it is considered as a basic blend of wood aged port that has been in the barrels for at least two years.
• Colheita: Tawny port from a single vintage is referred to as Colheitas, and instead of an indication of the age of the wine, as is the case with tawny port, the actual vintage year is indicated on the label. Colheita port may have spent a period of 20 years or more in wooden barrels before being bottled.
• Garrafeira: This is an unusual and rare intermediate vintage made from the grapes of a single harvest and combines oxidative maturation of years in wood with a further period of reductive maturation in large glass demijohns. The period in wood ranges between three and six years, followed by at least a further eight years in glass, before the port is bottled.
• Ruby port: This style of port is the cheapest and the most extensively produced. After the fermentation process it is stored in tanks made from either concrete or stainless steel to prevent oxidative aging. This preserves the rich claret colour of ruby port. The port in fined and cold filtered before bottling and generally does not improve with age.
• White port: White port is produced from white grapes and can be made in any style of port required.
• Crusted: Crusted port is a blend of port wines taken from several vintages and offers the blender the opportunity to make best use of the varying characteristics of different vintages. This style is bottled unfiltered and sealed with a driven cork. Like vintage port, it needs to be decanted before drinking. Crusted port improves with age, but the blender often intends to make this style of port approachable at a younger age. This port is required to age in the bottle for at least three years before being marketed, but most producers keep the bottles for considerably longer to ensure that the port is ready to be consumed when sold.
• Vintage port: Vintage port accounts for nearly 2% of the total port produced and is made from the grapes of a declared vintage year only. The decision on whether to declare a vintage is made in the spring of the second year after the harvest. This style of port is by far the most renowned, despite making up such a small percentage of total port production. Vintage port is aged in barrels for a maximum of two and a half years before bottling, and is further aged for another ten to 40 years in the bottle before reaching a proper drinking age. Since vintage port is aged in barrels for such a short time, the wine retains its dark ruby colour and fresh fruit flavours.

Madeira wine

Madeira wine is produced in a wide variety of styles, with the driest varieties consumed on their own as an aperitif, while the sweeter wines are consumed with dessert. Cheaper varieties are flavoured with salt and pepper and used for cooking purposes. The four chief styles of Madeira wine are named after the (noble) grape varieties from which they are produced. From driest to sweetest, they are:

• Sercial: This style is nearly fermented completely dry (0,5-1,5° Baumé) and has little residual sugar, as well as being characterised by high-toned colours, almond flavours and high acidity.
• Verdelho: This style is produced by halting fermentation earlier that with Sercial (1,5-2,5° Baumé) and is characterised by smoky notes and high acidity.
• Bual: In this style, fermentation is halted when the sugars are in the range of 2,5-2,3° Baumé and is characterised by a dark colour, medium-rich texture and raisin flavours.
• Malvasia: This style of Madeira wine’s fermentation is halted at 3,5-6,5° Baumé. The wine has a dark colour, rich texture and coffee-caramel flavour.

Marsala wine

Marsala is similar to port, Madeira and sherry and was originally fortified with alcohol to ensure it would survive during long ocean voyages. Traditionally, this type of wine is served as an aperitif between the first and second course of a meal. It may also be served chilled with Parmesan, Gorgonzola, Roquefort and other spicy cheeses, as well as with fruit or pastries and as a dessert wine when served at room temperature. It is frequently used in cooking and is especially prevalent in Italian dishes.

Marsala wine is produced from among others Grillo, Inzolia and Catarratto white grape varieties, although red grape Marsala wine is also produced. This style of wine contains between 15 and 20% alcohol by volume and is classified according to three levels of sweetness, colour and aging.

Read more about table grape production.

Sherry

Sherry is a style of fortified wine made from white grapes and is produced in a range of dry styles. These styles range from light versions, similar to white table wines such as Manzanilla and Fino, to darker and heavier styles such as Amontillado and Olorose, which have been allowed to oxidise as they are barrel aged. In the production of sherry, wines from different years are aged and then blended using a solera system before the sherry is bottled. For this reason, bottles of sherry do not generally carry a specific vintage year and may contain a small proportion of very old wine. There are three white grape varieties used to produce sherry, although winemakers in different countries often use different grape varieties:

• Palomino: This is the main grape variety used in the production of dry sherries. It produces a wine with very bland and neutral characteristics that is easily enhanced by the sherry winemaking process.
• Pedro Ximénez: Used in the production of sweet wines. After harvesting, this grape is usually dried in the sun for at least two days to concentrate its sugars.
• Moscatel: A less common grape variety used in a similar way to Pedro Ximénez.

– Theresa Siebert, ARC – Institute for Agricultural Engineering

The manual on the Agro-Processing of Fermented Beverages – Wine contains complete information on the products discussed. The manual is available from the ARC – Institute for Agricultural Engineering. Contact Elmarie Stoltz on 012 842 4017 or stoltze@arc.agric.za.