MOULDY-EARTHY FAULTS IN WINES: GEOSMIN IDENTIFIED AS THE MAIN COMPOUND RESPONSIBLE
Stéphane LA GUERCHE
The harvest of botrytized grapes displaying fungal or mouldy aromas is not a new phenomenon (1;2). However, over the last few years, several aromatic defects with a fungal, mouldy or earthy characteristic associated with a more or less evident occurrence of moulds on the grapes have been found in wines from different viticultural areas (Bordeaux, Val de Loire, Burgundy).
First studies have identified the presence of a compound with a strong wet earth and beetroot aroma in wines. It is (-)-geosmin, a well known water pollutant (3). This compound is found in musts before fermentation and its presence is always associated with grapes that were at least partially affected by grey mould (4;5).
However, geosmin is not the only compound responsible for the mouldy-earthy aromas of wines. Other earthy defects have also appeared in famous Burgundy appellations.
The significance of the quality degradation caused by these problems in wines produced from numerous grape varieties (Cabernet Sauvignon, Semillon, Gamay, Chenin, Pinot noir) led to an extensive study. Its objectives were to characterize the nature of the faults associated to these fungal and earthy aromas, and also to determine their biological origin and the conditions leading to their formation in the vineyard.
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Published on 05/20/2006
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