Mold - defect
A common olfactory defect is MOLD, caused by the presence of microorganisms such as mold and bacteria, due to a lack of hygiene in the cellar material, such as tanks or barrels. This defect manifests itself with a persistent aroma and flavor of damp earth/humidity/undergrowth that, if in high quantities, can significantly alter the aromatic characteristics of the wine, making it less pleasant and compromising its overall quality. Winemakers can prevent the onset of this defect by carrying out winemaking procedures through rigorous quality controls, in clean and sanitized environments. Despite efforts, mold can occasionally occur, even in the most careful productions.
It is interesting to know that one of the molecules responsible for the mushroom/mold aroma, 1-octen-3-ol, is often found in an unusual way in Ice Wines, known as Eiswein in Germany and Austria, produced from Riesling and Muscat Ottonel, and in Canada called Icewine, obtained mainly from Vidal, a hybrid grape variety of French origin. Ice wines are produced by pressing frozen bunches of grapes, which are left on the vine until December-January, so that intermittent frosts can concentrate the sugars, acids and aromatic substances of the grapes. However, the significant delay in harvesting the bunches and high humidity can favor the growth of mold on the grapes, which enrich the must with 1-octen-3-ol, generating an intense aroma of porcini mushrooms in the wine. It is noteworthy that high-quality ice wines do not have this mushroom olfactory note (L. Moio “Il respiro del vino”) Also the molecule Geosmin, responsible for the characteristic intense earthy smell that is perceived in the air after a rain following a period of drought or during a summer storm that suddenly wets the earth, can be found as a defect in wines contaminated by a fungus of the Penicillium family.
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