Noble rot
The noble rot (also precious maturity ) is called the appearance of the fungus Botrytis cinerea , also known as gray mold, at the ripe berries of the grape .
Noble rot forms on ripe grapes from around 80 degrees Oechsle or 12.5 KMW in warm autumn weather. The moisture required for the noble rot to grow is usually provided by early morning mist, while the days still have to be warm enough to promote the drying of the berries. Only a few wine-growing regions are characterized by such a climate.
The mold perforates the grapes with its enzymes , as the cell walls of the berry skin are broken down. As a result, in dry weather, the berries leak moisture and evaporate. The concentration of the ingredients in the juice of the berry increases and the amount of juice is reduced. At the same time, the fungus changes the composition of the berry. The fungus metabolizes sugar , acids and nitrogen . In relative terms, however, it consumes far more acid than sugar and releases metabolic products such as glycerine to the berry. These microbiological processes also change the color and flavor of the juice. This leads, for example, to the typical honey-like noble rot bouquet or botrytist clay .
In extreme cases, the concentration can increase the sugar content of the grapes up to 45%. This results in the highest must weights . These berries can be refined into high-quality musts for Auslese , Beerenauslesen or Trockenbeerenauslesen . The loss of quantity associated with the concentration can be compensated for by increasing the quality.
The wines made from these musts are usually very sweet because the sugar can only be partially broken down by the yeast during alcoholic fermentation due to its high concentration. Other special features of these wines are their extremely long shelf life and the botrytist tone.
High botrytis infestation in dry white wines has a negative effect on quality and leads to premature aging , a bitter taste and a repulsive odor.
In red wines , the enzyme laccase is released into the grapes when botrytis is attacked . The laccase is in turn present in the must or wine after pressing and is still active. Even with high SO 2 additions over 100 mg / l free SO 2 , the laccase is not inhibited or inactivated. It splits the structure of the coloring anthocyanins , which has a negative impact in red wine because the color then tends from red to orange-brown.
The aroma is shifted towards the botrytistone mentioned above and becomes more pronounced with storage. In Austria and Germany, Riesling and Traminer are often used for this.
Affects Botrytis cinerea but grapes that are not yet fully mature, the result is the dreaded in wet weather raw rot , also sour rot called.
The following wine-growing regions are known for outstanding noble sweet wines:
- France: Sauternes (mainly from Sémillon ), Anjou (from Chenin Blanc ) and Monbazillac, (mainly from Sémillon).
- Germany: Moselle , Rheingau
- Switzerland: Valais (from Petite Arvine )
- Austria: Neusiedlersee
- Slovakia / Hungary: Tokaj
- Romania: Cotnari (from Fetească Albă )
literature
- Helmut Hans Dittrich, Manfred Großmann: microbiology of wine. 3rd edition from 2005, Verlag Eugen Ulmer, ISBN 978-3-8001-4470-9 .
Web links
Individual evidence
- ↑ Manfred Klimek : Beloved pest: The mold botrytis. Published on July 29, 2009 on CaptainCork.com ( memento of the original from October 31, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Helmut Hans Dittrich, Manfred Großmann: Microbiology of Wine. 3rd edition, Verlag Eugen Ulmer, Stuttgart 2005, pp. 191-200.
