No self-respecting backbar seems to be without something ageing in a barrel these days – so it was a real joy to get some really expert insights into the world of wood recently from cask consultant Alban Petiteaux, MD of Oenowood International. The stats were mind-boggling: it takes 200yrs to grow a top-quality forest of French oak, with one tree selling for around E135,000, yet yielding only around 20% usable wood. Even after selection, a further 5% of all staves are rejected prior to coopering, with each of the remaining staves worth around E7 and a top flight Bordeaux cask around E650.
An analysis of the cellular structure of a single ring of a French oak revealed two distinct phases: the tubular spring wood, responsible for the aromatics, and the summer growth, which is far more tannic, while a series of graphs demonstrated the fluctuation of flavour compounds across different levels of char, and different types of wood.
The treatment of wood was also a focus. A period of seasoning in water and air is key to refining the organoleptic compounds in the oak, leading to a fall in tanning levels and an increase in aromatics. Toasting, meanwhile breaks down tannins, resulting in a decrease in structure and power, with optimum complexity reached at a medium toast. A really heavy toast, contrary to popular perceptions, actually creates a spirit with a lighter appearance, as the lignins become harder to release. The tight grain but porous structure of US oak ages spirit quicker, while the tannic but unporous structure of European oak takes longer.
Hot tips from Alban included Russian oak – lean on tannins and with a minerality good for white wine, and a recommendation that bartenders use spirit with an abv of 55% for best results when barrel ageing. Truly fascinating stuff – of which we hope to feature more in Imbibe soon.
Below are two slides from the presentation, courtesy of Alban Petiteaux and Oenowood International.