M – like Mizunara oak
What exactly is Mizunara oak?
Mizunara is a variant of the species Quercus Mongolica and literally means “water oak”, derived from the Japanese words mizu for water and nara for oak. The wood owes this name to its high moisture content.
Why is oak the preferred choice for maturing whisky in casks?
Oak wood (a member of the Quercus plant genus) is a favoured material for barrel production for many reasons. Because it is hard and very stable. Heat allows it to be easily bent into shape without breaking. Oak wood is also characterised by its remarkable durability, which means it can be used for many decades. Oak is also extremely resistant to various pests that can affect other types of wood. Compared to softwoods, oak has no resin channels, which prevents the release of undesirable flavours into the liquid contents. The natural porosity of the oak enables effective gas exchange with the environment, allowing the whisky to breathe in the cask and interact with the atmosphere. The dense grain of the oak reliably ensures that there is no unwanted leakage of the barrel contents. In addition, oak wood has a balanced ratio of volatile and non-volatile chemical ingredients that give the whisky its aroma, flavour and texture as it matures over the years. But only around a dozen of the 600 or so species of oak that exist worldwide are actually suitable for making barrels.
Where is the Mizunara oak native?
This oak species is widespread in East Asia, particularly in Japan, on the Korean peninsula and in north-east China. This rare and therefore precious wood is also used to make exclusive and luxurious furniture.
What are the special properties of Mizunara oak wood?
Mizunara wood is much more challenging for coopers to work with than European or American oak. This is because the wood is more porous and casks made from it can leak more often. For this reason, the logs are split with an axe rather than a saw, and the resulting staves are slightly thicker than usual at 38 mm. Japanese oak is also softer and therefore more difficult to shape. It has more branches than European or American oaks and does not grow so straight, but rather crooked, which makes the cooper’s work even more difficult. In addition, a Mizunara tree must be at least 150 to 200 years old to reach the appropriate size required for the production of suitable staves.
Is Mizunara oak expensive?
Yes. Due to the rarity and exclusivity of this precious wood, Mizunara oak is very expensive. The cost of a so-called puncheon (500 litre cask), which is popular in Japan, can easily exceed 5,000 dollars. Even if money is no object, Mizunara casks are extremely difficult to obtain due to the rarity of the wood and the aforementioned difficulties in production.
Which Mizunara casks does St Kilian have?
A few years ago, we at St Kilian had the good fortune to receive four fresh Mizunara barrique casks directly from Japan. These casks have a capacity of 225 litres and are mildly toasted. The wood came from trees around 250 years old in the forests of the northern Japanese island of Hokkaido and was carefully crafted by experienced coopers. We have filled these casks with both unpeated and our peated New Make. One cask was emptied after a full maturation of three years and launched as the first example of our ‘Exceptional Range’.
What flavours does the Mizunara oak impart to the maturing whisky?
Mizunara gives the whisky unique flavours that are often described as heavy oriental scents or reminiscent of Japanese shrines and temples. The wood produces an intensely fragrant kara aroma, a kind of oriental incense that was previously unknown in whiskies. Mizunara also gives the whisky flavours of sandalwood and ripe pineapple. It also has a high vanillin content and contains large quantities of the so-called whisky lactones, which give the maturing whisky coconut notes. Due to these very special flavours, whisky matured in Mizunara oak is highly valued all over the world.
