Odor detection threshold (ODT) and odor rejection threshold (ORT) determination of sotolon in Madeira wine: A preliminary study

Madeira is a fortified wine, well renowned worldwide. It is during the aging process that its characteristic bouquet is developed, through the formation of specific aromas. Sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is frequently pointed out as one of the molecules responsible for the aroma of the finest Madeiras. The present work serves as a preliminary insight on the sensorial impact of this compound in Madeira wine. The odor detection threshold of sotolon in a sweet-type Madeira was obtained by the 3-Alternative Forced Choice method. The estimated threshold value was obtained by 19 non-trained and non-expert panelists, within the spiked range 4-314 mu g/L. An odor threshold of 112 mu g/L was obtained using a 3-year-old Madeira with 6.3 +/- 0.4 mu g/L endogenous sotolon. This result is about 6-fold higher than those previously reported for other fortified wines. A Paired Preference test was chosen to determine the concentration at which the panelists would reject the wine spiked with sotolon. Nineteen panelists assessed a series of spiked concentrations ranging from 253-3464 mu g/L. Within this range, it is not possible to define the concentration value from which the aroma of sotolon it is no longer pleasant. Thus, an odor rejection threshold could not be obtained. Indeed, the study also suggests that sotolon does not become unpleasant at higher concentrations.