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Bibliografia : p. 47
Contém referências bibliográficas
Contém referências bibliográficas
Pesquisa de recolha documental realizada pelo Prof. Doutor Ernesto Candeias Martins nos anos 2010/2011
The purpose of this work is to evaluate the wine spirit aged by an alternative process
(staves combined with different micro-oxygenation levels) and its comparison with the traditional
process (wooden barrels). This evaluation was made by analyzing the volatile compounds and
sensory profile of the spirits during 365 days of ageing. The findings confirmed the role played
by oxygen in the volatile profile of aged wine spirits. Samples of alternative ageing modalities
were well distinguished from those of wooden barrels based on the volatile profile, namely on the
concentrations of several volatile phenols. From a sensory point of view, the results are promising
with high overall consistency scores obtained from samples of alternative ageing process modalities.
Alternative technologies for a more sustainable wine spirits' ageing have been studied but a lack of knowledge on the effect of oxygenation level remains. This work examined the behaviour of low molecular weight compounds, iron and copper of a wine spirit aged in 50 L demijohns with chestnut wood staves combined with three levels of micro-oxygenation or nitrogen. Compounds and mineral elements were quantified by HPLC and FAAS, respectively, in samples collected at 8, 21, 60, 180, 270 and 365 days of ageing. Results showed that most of the compounds underwent significant changes in their content over time and behave differently depending on the wine spirit's oxygenation level: higher contents of gallic acid, syringic acid and vanillin were associated with lower micro-oxygenation level while higher contents of ellagic acid, syringaldehyde, coniferaldehyde and sinapaldehyde resulted from higher one; lowest contents of these compounds were found in the nitrogen modality. Weak correlation between copper and the studied compounds was evidenced whereas closer relationship between iron, vanillin, gallic, syringic and ellagic acids at end of ageing was observed. This study provides innovative information on the role of oxygen in wine spirit's ageing, and on chestnut wood effect on wine spirit's mineral composition.
This research was focused on identifying gallotannins and ellagitannins degradation pathways to better understand their behavior in complex media such as wine spirits (WS). A WS was aged with chestnut wood staves with three levels of micro-oxygenation, nitrogen, and using wooden barrels. Gallotannins and ellagitannins were identified by LC-ESI-HRMS/MS using a Q-TOF in samples collected at 8, 21, 60, 180, 270, and 365 days of ageing, allowed comparing their relative abundances according to the ageing technology. It was established for the first time, the importance of oxygen in gallotannins and ellagitannins formation/degradation pathways in WS and shading light into the explanation for the steady increase of gallic and ellagic acid contents on WS during
ageing. The results also highlighted the presence of penta-O-galloyl-β-D-glucose, tetra-O-galloyl-β-D-glucose, tri- O-galloyl-β-D-glucose, di-O-galloyl-β-D-glucose, and mono-O-galloyl-β-D-glucose, 2,3-(S)-hexahydroxydiphenoyl-β-D-glucose, pedunculagin, isomers vescalagin/castalagin and two products stemming from ethanol-promoted oxidation of castalagin/vescalagin and vescalin/castalin, in the composition WS aged with chestnut wood.
A deep knowledge of oxygenation level effect on wine spirits’ ageing is imperative to understand ageing
chemistry and to select the most suitable technological option towards quality and sustainability. Following two
articles on the same trial, this work focused on colour, total phenolic index (TPI) and basic chemical characteristics
of a wine spirit aged in 50 L demijohns with chestnut wood staves together with three micro-oxygenation
(MOX) levels. Chromatic characteristics and TPI were monitored over time (8–365 days) while sensory colour,
alcoholic strength, acidity, pH and dry extract were assessed at the end of ageing. Results showed that stronger
oxygenation promoted significantly faster colour evolution (lower lightness, higher chroma, red, yellow and
brown hues) and higher TPI than mild and intermediate oxygenation until 60 days, probably by favouring the
leaching of outer wood layers and extraction/degradation of tannins. No significant differences were found
between these ageing modalities at 365 days. Outcomes suggest that the stronger MOX is the most suitable
modality in terms of quality and sustainability. Significant differences between wine spirits resulting from MOX
and control modality (slower colour evolution, lower TPI and dry extract) confirms the oxygen pivotal role in
wine spirit’s ageing, particularly in the colour evolution
