Spirits are kept, for a shorter or longer time, in vessels of different materials: lined concrete tanks, metal or stainless-steel tanks, plastic tanks, wooden vessels and so on. When the aim is for a spirit such as rakija to improve its taste and aroma over time, wooden vessels are used most often.
Several woods are used for this, chestnut, mulberry, acacia and elm among them, but the most popular and most suitable is certainly oak.
Oak, the main maturing vessel
Oak has the strength and elasticity needed for barrels and casks, and splits and bends well. It insulates well enough, holds liquid but lets gas through: its porosity lets oxygen from the air diffuse into the distillate and take part in maturing. In practice, the oxygen that comes through the staves is small compared with what reaches the spirit through the bung hole.
Oak gives no unwanted aromas or flavours to what it holds. On the contrary, the extract of the wood becomes part of the bouquet and the quality of the distillate, and its fine porosity and particular make-up give the spirit colour and very distinctive aromas. Among broadleaf trees, oak is prized for its strength, durability and beautiful grain.
In Europe, barrels for rakija and wine are made mostly of sessile oak and pedunculate oak, which grow from northern Spain to Russia and are often found mixed in France.
How oak shapes a spirit
European oaks differ in their physical and chemical properties, and so in their effect on spirits and wines, depending on where they grow, how fine their grain is and how the forest is managed.
Pedunculate oak has a coarser grain, more porosity and lets more wine or alcohol through the staves into the air. Traditionally, coarse-grained staves such as those from Limousin in France are sought for ageing spirits, as they allow more exchange (evaporation, oxidation, extraction from the wood) than fine-grained staves from Allier and the Vosges, used mainly for wine.
The two species also differ chemically. Pedunculate oak is rich in ellagitannins and fairly poor in aromatic compounds such as β-methyl-γ-octalactone and eugenol; sessile oak is roughly the opposite and especially rich in β-methyl-γ-octalactone. That is why sessile oak suits making and keeping many kinds of wine, and pedunculate oak the ageing of spirits.
European oak must always be split along the grain for the barrel to hold liquid; American white oak can be sawn without leaking, so American barrels are much cheaper. White oak grows widely in the central and eastern United States and is traditionally used for whisky and rum, though more and more for wine and cognac-type drinks too.
Our oak-matured rakija
Zlatna dunja, our first premium rakija, has a perfectly balanced taste and aroma: the fresh scent of quince with notes of nutmeg and vanilla, while maturing in oak gives it fullness and a barrique taste.
Zlatna šljiva, our second premium rakija, is a blend of Požegača, Čačanska rodna, Čačanska lepotica and the native Moravka, bottled with flakes of 23-carat gold. Its intense barrique taste and aroma, with notes of vanilla and dried plum, come from ripening in the oak cask.
