Denomination (also known as wine grape) for those grapes from vines that are used to produce wine or spirits such as brandy(Armagnac, Cognac, Metaxa etc.) and even vodka (together around 85% worldwide). Other groups are table grapes (table grapes) and raisins intended for consumption. There are about 8,000 to 10,000 different grape varieties worldwide, whereby the morphology(leaf shape as well as size, texture and colour of the grapes or berries) is characteristic of the respective variety. The grapevine develops the grape during the annual vegetation cycle. As a rule, the grape harvest takes place at the best possible physiological ripeness. For predicate wine types such as Spätlese, Beerenauslese, Trockenbeerenauslese or Eiswein, this occurs much later because a special grape condition is required for this. Especially in Austria and Germany, a certain sugar level of the grapes at harvest is an important criterion for the later wine quality level (see must weight).
Strictly speaking, the term "grape" is actually wrong; because a grape has only side stems without branches. The correct botanical name would be panicle. The size, the number of berries and the weight of a grape, as well as the number of grapes and the resulting yield per vine vary and depend on the grape variety, pruning, form of cultivation, weather conditions, wine quality and wine type (see the formula under yield). In a study lasting several years, researchers from the Weinsberg Viticulture Institute determined the average number of berries per grape of some classic grape varieties. The results: Silvaner 110, PinotNoir 115, Riesling 120, Kerner 140, Müller-Thurgau 160, Trollinger/SchiavaGrossa 155 and Lemberger/Blaufränkisch 190 berries. There was a considerable variation over different vintages. Lemberger, for example, was between 150 (2008) and 225 berries (2004), whereas Kerner was exactly the opposite, between 125 (2004) and 200 (2008) per grape.
During pruning, almost all grape varieties develop about 1.6 to 2.5 grapes per shoot, depending on their fertility. When bifocal cones are pruned, these values are slightly, but sometimes significantly lower, depending on the variety. For example, Gewürztraminer with approx. 0.5 to 0.8 grapes per shoot would have extremely low fertility. In the Dornfelder, approx. 1 to 1.3 grapes/shoot can be expected. Riesling still shows quite high fertility even with this pruning system with about 1.5 to 2 grapes per shoot. The average weight of a grape is 180 to 200 g (Riesling 100 to 200 g, Pinot Noir 150 to 230 g, Blaufränkisch 180 to 280 g). A vine with 8 to 12 grapes gives a total weight of 1.5 to 2.5 kg. This results in 1.5 to 2 bottles of wine with the standard volume of 0.75 l.
The grape must obtained by pressing (pressing) forms the basis for the wines. The residue is called marc (grape marc), the sediment after fermentation is called tank bottoms. Both are used to produce high-quality brandies by distillation. The grape berry sits on a short stalk, which is located on the stem framework (comb or centaury, bot. pedunculus). At the opposite end there is a dead tissue on the surface, which represents the rest of the stylus and the stigma (female organ) of the former flower bud. The number of berries per bunch depends, among other things, on the course of the vegetation cycle and the grape variety and can range from several dozen to 600 or more berries. Compact, dense-berried grapes are susceptible to fungal diseases and grape rot, so a certain amount of loose berries is advantageous.
From each individual blossom of a peach, a grapevine is formed, provided that fertilization has taken place. Under the skin of the grape is the slugs (light-coloured flesh) which connect to the stalk. Below this are the darker fruit flesh (pericarp and mesocarp) and the fruit juice (grape must). With the exception of the red-fleshed Teinturier varieties, the flesh is always light to grey, regardless of the colour of the skin (bellows). The berries contain the main components(water, acids, sugar etc.) or other ingredients of the future wine and give it its character (see total extract). In the centre of the berry is the core chamber with mostly two to three, rarely up to five or six seeds. Each of the seeds can potentially give rise to a different grape variety (see flower and flower bud).
For table grapes, so-called seedless berries are desired. However, they also contain seeds, but smaller and in smaller numbers and of a softer consistency that they are hardly noticeable when consumed. The seeds are not so important for vinification, they also contain tannin. In white wine they are usually separated from the grape must with all other solid parts during pressing. Especially in red wine, the mash fermentation leads to a longer contact of must and mash and thus also the pips. The kernels are also used for the production of grape oil.
There is a direct correlation between berry size and wine quality, which is particularly beneficial for red wines when they are made from small-berry grapes. The berry skin (pods or bellows = exocarp) contains the important taste-determining substances anthocyanins (colouring agents) and phenols such as tannins. With smaller berries, these substances make up a higher proportion due to the resulting better ratio of surface to volume. Potentially good wine grapes actually lift much smaller berries compared to table grapes (which usually produce simple wines when used as wine press grapes). On average, a high-quality Cépages nobles berry weighs one to two grams, and up to ten grams for smaller varieties. In the vineyard, efforts are also made to achieve higher quality by measures such as deliberately inducing water stress and thus smaller berries. An important quality criterion is also a balanced proportion of sugar and (especially in white wine) acids.
All aids, work and measures in the vineyard during the vegetation cycle can be found under the keyword vineyard care. Complete lists of the numerous vinification measures or cellar techniques, as well as the various types of wine, sparkling wine and distillate regulated by wine law are included under the keyword vinification. Comprehensive information on wine law can be found under the keyword wine law.
Grape and flower bud: Gemeinfrei, Link
Vine old: by CecileOSaveurs from Pixabay
Grape varieties: Ursula Brühl, Doris Schneider, Julius Kühn Institute (JKI)
Grape with core: From fr:Yelkrokoyade - author, CC BY-SA 3.0, Link
Grape berry with ingredients: By Mariana Ruiz Villarreal (LadyofHats), Public domain, Link
edited by Norbert F. J. Tischelmayer, March 2019