What influence do barrels have on wine?
Countless exchanges occur between oak and wine. However, the ability of a cask to create exchanges with wine only lasts for three to four years. After this lapse of time, it becomes a mere container due to the tartaric acid crystals deposited on the wood.
Wine is transformed in the barrel through a process called redox. It is believed that the wine undergoes gradual oxygenation via the bung hole but also through the wood and joints between the staves. Regular racking adds the final dose of oxygen necessary for the process to occur.
1. Barrels stabilise colour
When wines are matured in new barrels, a combination of tannins (from the wine and the oak) and anthocyanins stabilises the colour.
2. Barrels promote concentration in the wine
During the redox process in the barrel, the wine becomes concentrated and therefore gains length on the palate. Over an 18-month ageing period in a barrel, the wine loses approximately 10% of its initial volume and therefore needs to be topped up frequently to avoid contact with air – which would turn it to vinegar.
3. Barrels allow the extractible components in wine to be dissolved
A new cask imparts tannins to wine but also other volatile phenol compounds referred to as ‘tertiary aromas’. The main aroma compounds are:
Aroma compounds in oak :
Lactone : coconut
Phenolic aldehydes : vanilla
Phenyl ketones : vanilla, oak, spice
Phenols : clove, smoke, pepper, spice, leather, carnation, ink
Toast compounds :toasted almond, bitter almond, toast, smoke
Furfuryl alcohol from furfural : coffee
The geographical origins of the timber, the species of oak (sessile, English or American) and the grain of the oak have an impact on the quality of the cask and the resultant wines.
Producing a cask requires stave oak trees. The main supplier in France is the French forestry commission, ONF. The staves must then dry in the open air for approximately two years before being assembled.
The toast then has the most direct impact on aromas that develop in the wine. A heavy toast produces toast notes whilst medium to light toasts produce notes of vanilla pod and fresh oak respectively, hence a degree of ‘sweetness’.
Maturing wine in casks must promote harmonious results where the wine does not play second fiddle to the barrel but is enhanced by it. This is the result we are looking for at Château Fougas.