Oak in winemaking
Barrels, Tanks, Amphoras… What’s the Deal with Fermentation and Maturation Vessels?
One of the most common questions I’m asked is: why do producers use oak, and what impact does it have? Choosing to use oak isn’t a flippant decision—a new barrel can cost anywhere from €250 to thousands, depending on size, origin, and craftsmanship. Let’s delve into why it matters and why oak has been integral to winemaking for centuries.
The History of Oak in Winemaking
Barrels have been used to transport liquids since Roman times—though early versions looked quite different from those we see today. Initially, their use was purely practical, but by the 1st century BC, winemakers discovered that oak barrels also enhanced the wine itself. Oak became the wood of choice because it is softer (and easier to bend) than many other woods, toasts well, and was widely available across Europe.
Tasting from the barrel
Where Does Oak Come From?
Most winemaking oak comes from France or the US, with some Austrian oak also used. Each type has distinct characteristics:
French oak (from one of five key forests—Allier, Limousin, Nevers, Tronçais, and Vosges) is known for its elegance, contributing subtle notes of vanilla, clove, and baking spice. It also has a higher concentration of ellagitannins, which enhance structure rather than aromatics.
American oak imparts more pronounced aromas, often with hints of coconut, sweet spice, or chocolate. It also grows significantly faster, reaching maturity in around 80-100 years compared to 150-200 years for European oak.
How Barrels Are Made
Stave Selection & Cutting: Staves, cut from the tree’s heartwood, must fit together perfectly for a watertight seal. Modern cooperages use laser-guided jointers for precision, ensuring even pressure distribution and durability.
Varying Stave Widths: Using different widths reduces leakage and improves the barrel’s overall integrity.
Seasoning: Staves are air-dried for 2-3 years to enhance their physical and chemical properties. Proper stacking allows airflow and controlled moisture reduction (from 40-70% to 14-16%).
Barrel Construction: Staves are softened with water and fire to prevent damage during shaping, then bound with metal hoops.
Toasting & Heads: French oak barrel heads are typically left untoasted, while American oak heads are toasted to soften their influence on the wine.
Toasting Process: Barrels are toasted over an open flame using scrap oak. Slow, controlled fires ensure deeper and more consistent toasting, which significantly impacts the wine’s character.
Final Assembly: Hoops are pressed into place, grooves are cut for the barrel heads, and a bung hole is drilled. The exterior is sanded, and hoops are reapplied for a finished look.
A 330l barrel being toasted at Taransaud Cooperage in France, before the final hoops are fitted
What Does Oak Add to Wine?
Flavour & Aromatics – Vanilla, clove, cedar, toast, spice (varies depending on barrel type and toast level).
Texture - barrel aging typically helps a wine gain a smoother, richer mouthfeel
Stability – Oak can help stabilise a wine’s structure.
Oxygenation – Tiny pores in the oak allow micro-oxygenation, softening tannins and aiding maturation.
What are the key considerations for a producer?
Size – the bigger the barrel the less contact the wine has with the wood, therefore less flavour
Toast - light toast vs medium toast etc. The higher the toast the more smokey the flavour imparted
Origin – As mentioned above, each origin gives a different style and flavour
Cooperage – Each cooperage has a unique style, producers will often work with a range and use the different barrels as blending components or to achieve consistency over vintages
How Can Oak Use Be More Sustainable?
When you consider that a 180-year-old tree may yield only three or four barrels, sustainability becomes a crucial concern. Winemakers and coopers are finding ways to reduce waste and ensure responsible oak use:
Reusing barrels – Extending barrel lifespan reduces the need for new production.
Sourcing sustainably – Choosing barrels from PEFC-certified cooperages ensures oak comes from responsibly managed forests.
Utilising the whole tree – Only 5% of a tree is used for barrels, so the rest must be repurposed to minimise waste.
Oak alternatives – Chips, staves, and barrel inserts can replicate oak influence while reducing demand for new barrels.
Barrel inserts – Extending a barrel’s lifespan by adding inserts can enhance sustainability without compromising quality.
Next time you sip a wine, and notice vanilla notes or perhaps softer tannins - take a moment to appreciate not just the grapes and terroir, but the craftsmanship of the barrel that shaped it.
