In Midleton Distillery, we use a variety of European oak types in the maturation of our whiskeys. The wooden casks that Jameson matures in are an important aspect of the magical work that takes place during the maturation process. My role requires passion and an in-depth knowledge of all the various factors involved in the maturation of whiskey. Another key aspect in all of this is the importance of sourcing quality oak for maturation.
Spanish oak plays a significant part in the maturation of many of our whiskeys. In the northwest of the Iberian Peninsula, there are three main species of oak that can be used in cask making, Quercus robur, followed by Quercus petraea and finally, Quercus pyrenaica.
From a forest in Galicia in Northern Spain, the oak is quarter sawn in the Maderbar sawmills in Baralla, transferred to Jerez for air drying for 15 to 18 months and then seasoned with Oloroso Sherry for two years. The process involves so many people, several stories and quite an amount of logistics. The entire cycle could take over 150 years if you include the growing time of the tree. Sometimes it’s necessary to stand back and absorb everything that happens in the process.
The Sherry Butt flavour comes from a combination of the Spanish oak and the Oloroso seasoning. The contribution of the Spanish oak is just as important to the flavour profile as the seasoning process with Oloroso. In comparison to American oak, Spanish oak has a very different composition. American oak contains higher amounts of certain compounds such as vanillin and oak lactones than European oak. On the other hand, Spanish oak has higher levels of tannins, colour and other wood extractives.
The wood compounds along with the Oloroso seasoning process contribute aromas and flavours of dried fruits, Sherry nuttiness with figs and dates. If we use Redbreast as an example, this whiskey has a beautiful contribution of the Spanish oak along with the Oloroso seasoning. We get a wonderful contribution of dried fruits and Christmas cake characteristics. If you want to taste this influence yourself try our Redbreast Lustau Edition, the result of a decades-long partnership between Bodegas Lustau and our Midleton Distillery.
A love of the process and the collaborative endeavor is key to all work at Irish Distillers. From the moment, you walk in the gates of the distillery the enthusiasm, dynamism and commitment to quality becomes apparent very quickly.

Written by Kevin O’Gorman, Head of Maturation