Chemicals with sweet aroma descriptors found in Portuguese wines from the Douro region: 2,6,6-trimethylcyclohex-2-ene-1,4-dione and diacetyl.
2,6,6-Trimethylcyclohex-2-ene-1,4-dione (TMCHD), a norisoprenoid with a sweet honey aroma descriptor, is reported for the first time as a minor constituent of single-varietal table and fortified wines from the demarcated Douro region. Olfactory gas chromatography (GC-O) of a volatile wine extract, previously isolated by preparative gas chromatography, indicated the presence of a zone containing an intense honey descriptor. The targeted odor compound was identified by GC-MS, GC-O, and Kovats index. Quantitative analysis using a selected characteristic ion (m/z 96) indicated that young Douro fortified wines from the 1997 vintage contained up to 4 microg/L TMCHD. The sweet honey sensory threshold limit for TMCHD in a model Port wine solution was found to be 25 microg/L. TMCHD is therefore only likely to contribute as a collective element to Port wine aroma. The wine volatile diacetyl was identified as a strong contributor to the sweet caramel aroma descriptor often associated with Port.
Rogerson
F S
FS
Centro de Investigação em Química, Departamento de Química do Porto, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal. steverogerson@mail.telepac.pt
Castro
H
H
Fortunato
N
N
Azevedo
Z
Z
Macedo
A
A
De Freitas
V A
VA
D002849:Chromatography, Gas / Q000379:methods; D003510:Cyclohexanes / Q000032:analysis*; D003931:Diacetyl / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D009812:Odorants; D011174:Portugal; D012903:Smell; D014920:Wine / Q000032:analysis*
D003510:Cyclohexanes; C428327:2,6,6-trimethylcyclohex-2-ene-1,4-dione; D003931:Diacetyl