The grape variety used for a wine is the most influential factor in determining its taste. The factors that determine the inherent flavor of any grape variety are the same as those that determine the varietal taste of any fruit. How they affect the taste of wine is outlined below.
The smaller the fruit, the more concentrated the flavor will be. Thus most classic grape varieties, such as Cabernet Sauvignon and Riesling, have small berries, although some varieties that rely more on elegance than power of concentration, such as the Pinot Noir, may yield large berries. Many varieties are known as petit- or gros something, and it is usually the petit that is the better variety—Petit Vidure is Cabernet Sauvignon; Gros Vidure, Cabernet Franc.
The skin contains most of the aromatic characteristics with which we associate the varietal identity of any fruit. Its construction and thickness is, therefore, of paramount importance. For example, the thick-skinned Sauvignon Blanc produces an aromatic wine that, when ripe, varies in pungency from “peach” in a warm climate to “gooseberry” in a cool climate, and when underripe varies in herbaceousness, ranging from “grassy” to “elderflower” and even “cat’s pee.” Meanwhile the thin-skinned Sémillon produces a rather neutral wine, although its thin skin makes it susceptible to noble rot and is thus capable of producing one of the world’s greatest botrytized sweet wines, with mind-blowing aromatics.
SKIN COLOR AND THICKNESS
A dark-colored, thick-skinned grape, such as Cabernet Sauvignon, produces very deep-colored wines, while the lighter-colored, thinskinned grapes, such as Merlot, produce a less intense color.
ACID–SUGAR RATIO AND PRESENCE OF OTHER CONSTITUENTS
The grape’s sugar content dictates the wine’s alcohol level and the possibility of any natural sweetness; together with the acidity level, this determines the balance. The proportions of a grape’s other constituents, or their products after fermentation, form the subtle nuances that differentiate the varietal characters. Although soil, rootstock, and climate have an effect on the ultimate flavor of the grape, the genetics of the vine dictate the end result.
THE VITIS FAMILY
The vine family is a large and diverse family of plants ranging from the tiny pot-plant Kangaroo Vine to Virginia Creeper. The Wine Vine Tree, (see below), shows how the Vitis vinifera, the classic winemaking species, relates to the rest of the vine family. The Vitis vinifera is one of many belonging to the subgenus Euvites. Other species in this subgenus are used for rootstock.
PHYLLOXERA VASTATRIX—PEST OR BLESSING?
The vine louse—Phylloxera vastatrix—that devastated the vineyards of Europe in the late 19th century still infests the soils of nearly all the world’s winegrowing regions. At the time, it was considered the greatest disaster in the history of wine, but with hindsight, it was a blessing in disguise. Before phylloxera arrived, many of Europe’s greatest wine regions had gradually been devalued because of increased demand for their wines. This led to bulk-producing, inferior varieties being planted, band vineyards being extended into unsuitable lands. As phylloxera spread, it became apparent that every vine had to be grafted onto phylloxera-resistant American rootstock. This forced a much-needed rationalization, in which only the best sites in the classic regions were replanted and only noble vines were cultivated, a costly operation that vineyard owners in lesser areas could not afford. The grafting took France 50 years, and enabled the Appellation d’Origine Contrôlée system to be set up. It is hard to imagine what regional or varietal identities might now exist if phylloxera had not occurred.
Hundreds of rootstock varieties have been developed from various vine species, usually Vitis berlandieri, V. riparia, or V. rupestris, because they are the most phylloxera-resistant. The precise choice of rootstock is dependent on its suitability to the vinestock on which it is to be grafted as well as on its adaptability to the geographical location and soil type. The choice can increase or decrease a vine’s productivity, and thus has a strong effect on the quality of the wine produced from the grapes. Generally, the lower the quantity, the higher the quality.