Bottle ageing is considered essential for most premium red wine production. An important aim of bottle ageing of wine is to achieve a balance between the oxidative and reductive development. This is typically evaluated by the accumulation of aldehyde compounds (causing oxidative off-flavour) and sulfur-containing compounds (causing reductive off-flavour) in the wine [1]. Although studies have been performed using variable amounts of oxygen available to the wine during bottle ageing, the impacts of viticultural practices on ageing processes have been studied less.
This research investigated the impacts of viticultural conditions (2 grape varieties, 2 vineyard locations and 2 fruit maturities) and variable bottle ageing conditions (3 oxygen availability regimes and 4 bottle ages) on red wine composition, with a particular focus on the production of aldehyde and sulfur-containing compounds in wine. Analysis of the total concentrations of the key aroma compounds was performed by LC-QQQ-MS (aldehyde compounds in their hydroxyalkylsulfonate forms), HS-GC-SCD (sulfur-containing compounds) and HS-SPME-GC-MS (esters, C6 compounds and terpenes). After 24-month of ageing, all of the measured sulfur-containing compounds showed increased concentrations in all wines.
For the wines made from the same grape (i.e. same variety, vineyard and harvest date), the high oxygen availability treatments contained lower concentrations of sulfur-containing compounds compared to the low oxygen treatments. Generally, methional, 2-methylpropanal, 3-methylbutanal, 5-methylfurfural and furfural exhibited increased concentrations with time, while phenylacetaldehyde, benzaldehyde and hexanal showed decreased concentrations.
Chemometrics analysis showed that based on the compositional analysis, samples could be separated primarily based on wine ageing and the viticultural conditions adopted. Regardless of the oxygen regimes or the ageing time during the bottle ageing, the samples could be always separated according to the viticultural conditions of the grape. These results indicate the importance of the viticultural conditions of the grape on the ageing of wine, despite the extent of ageing or oxygen exposure.
[1] Ugliano, M. Oxygen contribution to wine aroma evolution during bottle aging. 2013. Journal of Agricultural and Food Chemistry. 61(26): 6125-6136.
Authors: Xinyi Zhang, Nikolaos Kontoudakis, Katja Šuklje, Guillaume Antalick, John Blackman, Andrew Clark
Charles Sturt University, National Wine and Grape Industry Centre Locked Bag 588 – Boorooma St. Wagga Wagga NSW 2678 – Australia
Email: xizhang@csu.edu.au
Keywords: bottle ageing, viticultural conditions, oxidative-reductive development