Wine Fault

Geosmin

Additional

Geosmin produces intensely earthy, muddy, or beetroot-like aromas at extremely low detection thresholds. In wine it often traces to contaminated grapes, cellar biofilms, or water sources rather than typical fermentation faults.

Also known as: Earthy taint, Muddy aroma, Actinomycetes taint

Typical severity: High

Cause

Geosmin compound — typically microbial origin from Actinomycetes or certain molds — transferred into must or wine.

How it occurs

Muddy vineyard conditions, contaminated irrigation water, dirty equipment biofilms, or cork and cellar mold can introduce geosmin. Even ng/L concentrations are sensorially apparent.

Prevention

Clean water sources, equipment sanitation, grape sorting, and rejecting muddy or flood-affected fruit.

Descriptors created

Descriptors reduced

Commonly confused with

Common wine styles

Common grape varieties

Common regions

Related winemaking techniques

Serving implications

Beginner explanation

Geosmin smells like wet soil after rain — distinct from Brett's barnyard leather and usually unmistakably muddy.

FAQ

Can geosmin be removed from wine?
Very difficult — sensory thresholds are so low that even minor contamination persists through production.
Is geosmin a grape fault or cellar fault?
Both pathways exist — vineyard mud exposure and cellar biofilms are common sources.

Related ontology entities

See also

Fault identification guidance reflects common wine education practice and may vary by wine style, age, and context.