Through natural yeasts (also natural yeasts, environmental yeasts, wild yeasts, grape yeasts, vineyard yeasts) caused spontaneously occurring fermentation in the winemaking, Until the middle of the 19th century, yeast was not known to be the cause and was only created by Louis Pasteur (1822-1895) proven. Until the 1970s, the wines were usually the product of spontaneous fermentation. The natural yeasts are to a large extent in the air in the vineyard and are insect like vinegar flies (Fruit flies) spread. These then reach the cellar with the grapes. However, they not only come from the vineyard, but also from the cellar in the vicinity of the company. The amount is enough to make a spontaneous fermentation trigger.
In recent years, this form of winemaking has been linked to the Terroir-thoughts became popular again. For the purpose of funding, too rape and lees (Press and yeast residues) for one fertilization used in the vineyard to promote the specific emergence of certain and vineyard-specific natural yeasts. Spontaneous fermentation can produce excellent, but also undesirable results, since it is much more difficult to control than with cultivated yeasts. There are a number of wild types of yeast, which of them actually “prevail” during fermentation is more or less left to chance. Some of the yeast species end at 4% vol alcohol content their activity, which creates the risk of fermentation getting stuck. Wild yeasts can also cause unpleasant metabolic products.
Today, fermentation is mainly initiated by specific yeasts (pure breeding yeasts) that are suitable for the respective type of wine, in order to ensure that the fermentation process proceeds as perfectly as possible. The fact is, however, that yeasts of the Saccharomyces species (pure breeding yeasts) are also involved in spontaneous fermentation, since these are also in the vineyard and in the cellar surroundings. And even with controlled fermentation with breeding yeasts, natural yeasts are particularly involved at the beginning, this can hardly be prevented. An equally practiced form is to let the fermentation begin with natural yeasts and later to add culture yeasts, which then "take command". Spontaneous fermentation with cool fermentation temperatures, very sugar-rich musts, musts from rotten grape material, pasteurized musts and when sparkling is rather difficult.
When it comes to making red wine, the skins get a lot more vineyard yeast into the mash. This means that compared to white wine production, a good fermentation process is also easier with natural yeasts (fermented, dry wines). Spontaneous fermentation wines are often characterized by more glycerin and higher alcohols, and possibly more volatile acids and higher residual sugar out. However, it cannot be said that such wines are generally of better quality. In conclusion, it should be noted that the term "spontaneous fermentation" (or similar) has no meaning in wine law. In practice it is used quite flexibly. When a small batch of must is fermented spontaneously and the resulting yeast is used for the rest of the must, it is, so to speak, an "in-house breeding yeast".
Complete lists of the numerous vinification measures or cellar techniques, as well as the wine, sparkling wine and distillate types regulated by wine law are under the keyword winemaking contain. There is extensive wine law information under the keyword wine law,