Earthy off-flavour in wine: evaluation of remedial treatments for geosmin contamination.

Seven treatments (activated charcoal, bentonite, PVPP, yeast cell walls, potassium caseinate, zeolite and grape seed oil) were evaluated for their efficacy in decreasing the concentration of geosmin, responsible for earthy off-flavour in wine. In the red wine the potassium caseinate and grape seed oil treatments decreased the concentration of geosmin by 14% and 83%, respectively, while in the white wine, the activated charcoal and the grape seed oil were able to decrease the concentration of geosmin by 23% and 81%, respectively. The effective treatments in decreasing geosmin also decreased aroma volatile compounds, most of all esters, responsible for fruity notes. Considering the OAVs (concentration/odour threshold) only the treatment with grape seed oil was able to decrease the relative contribution of geosmin to the profile of the odour active compounds, both in red and in white wine. Sensory analysis confirmed the efficacy of the grape seed oil as a remedial treatment.