Noble rot
The noble rot (also precious maturity ) is called the occurrence of the fungus Botrytis cinerea, also known as gray mold, on the ripe berries of the grape.
Noble rot forms on grapes from about 80 degrees Oechsle and 12.5 KMW in warm autumn weather. The moisture necessary to the growth of noble rot then provide mostly early morning fog as the days have to be warm enough to promote drying of the berries. Few wine-producing regions are characterized by such a climate.
The mold is perforated with its enzymes, the grapes, because the cell walls of grape skins are removed. As a result, occurs in dry weather from the berries and moisture from evaporating. The concentration of the components in the juice increased the berry juice quantity is reduced. At the same time, the fungus alters the composition of the berry. Fungal metabolized sugars, acids and nitrogen. However, relatively it consumes far more acid than sugar and are thereby metabolites such as glycerol to the berry from. These microbiological processes change the color and flavor of the juice. This leads for example to the typical honey-like Edelfäulebukett or botrytis.
The concentration can rise up to 45% in extreme cases, the sugar content of grapes. This has the highest Mostgewichte result. These berries can be further refined into high quality musts for Auslese, Beerenauslese or Trockenbeerenauslese. The associated with the amount of concentration loss can be compensated by increase in quality.
The wines produced from these musts are usually very sweet because the sugar can be degraded due to its high concentration of the yeasts in alcoholic fermentation only partially. Other special features of these wines is their extremely long shelf life and the botrytis.
High Botrytis in dry white wines affects reduce the quality and leads to premature senile, a bitter taste and offensive odor.
Red wines is at Botrytis attack a specific enzyme, laccase, discharged into the grapes. Laccase is available again after pressing the must / wine and still active (even with high SO2 doses over 100 mg / l free SO2 laccase is not inhibited / inactivated) and splits the structure of the coloring anthocyanins on what is in itself red wine makes a negative impact, the color tends then from red to orange -brown.
In white wine the color depends on the amount of votes laccase (as well as red wine, white wine only when it is better visible ). This can range from shades of yellow to ( at worst ) to very brown and almost cognac -like brown color. The aroma is moved to the botrytis above, this becomes more pronounced with aging. In Austria and Germany Riesling and Traminer is to often used.
However, Botrytis cinerea infects grapes that are not yet fully developed, the result in wet weather the dreaded raw rot, also called sour rot.
The following wine-producing regions are known for outstanding sweet wines:
- France: Sauternes ( predominantly from Semillon ), Anjou ( Chenin Blanc ) and Montbazillac ( mainly from Sémillon ).
- Germany: Mosel, Rheingau
- Switzerland: Arvine ( from Wallis )
- Austria: Lake Neusiedl
- Slovakia / Hungary Tokaj
- Romania: Fetească Alba ( from Cotnari )