Mizunara oak explained
Mizunara oak casks are associated with Japanese whisky and with aromas of sandalwood and temple incense. They began as a wartime substitute and became a prized rarity. Here is what makes the wood different and how to recognise it in a glass.
A Japanese oak with a wartime story
Mizunara is Japanese oak, Quercus mongolica var. crispula (often written Quercus crispula). It grows in northern Japan, particularly Hokkaido. Japanese distillers turned to it when imported casks became hard to get during the Second World War. It was the oak they had to hand.
It was not an easy choice. Early Mizunara casks were said to leak and give a strong, raw wood character to young spirit. Distillers persisted. With long maturation, whisky from these casks developed aromas that people started to seek out. Our guide to how Japanese whisky is made puts this in context.
Why it is so hard to work
Mizunara has fewer tyloses than American white oak. Tyloses are the growths that block the wood's vessels and keep a cask watertight. With fewer of them, Mizunara is more porous and more likely to leak. The trees also tend to grow with twists and knots, so getting long, straight staves is difficult and wasteful.
The wood is soft for an oak and needs careful seasoning. Trees take a long time to reach a usable size. All of this adds up to a cask that is expensive and scarce. Many distilleries that use Mizunara use it as a finishing cask for months rather than for full maturation over many years.
Sandalwood, incense and coconut
The aromas linked with Mizunara are distinctive. Tasters describe sandalwood, agarwood (oud), temple incense, coconut, spice and sometimes a light floral note. For Indian drinkers, the sandalwood and agarbatti comparison is often immediate and easy to recognise.
These notes tend to come through more with longer maturation. Young whisky that has only spent a short time in Mizunara may show more tannin and raw wood than incense. That is why Mizunara character is often associated with older Japanese whisky. A finish of a year or less gives a hint rather than the full picture.
How it compares with other oaks
Next to American white oak, which gives vanilla, coconut and caramel, Mizunara has a more perfumed and spicy profile. It shares some coconut notes, because it also contains oak lactones, but it adds the incense and sandalwood aromas that American oak rarely shows.
Next to European oak, which brings tannin, spice and often dried fruit from sherry seasoning, Mizunara tends to feel more aromatic and lighter in tannin once mature. Our guide to American oak versus European oak explains the other two in more detail.
Mizunara outside Japan
Mizunara casks are now used by some distilleries in Scotland, the US and elsewhere, usually as finishes or small parts of a blend. Labels that mention Mizunara may describe full maturation, a finish of a few months or a small share of the whisky. The label may not say which.
There is also a lesson here for any distillery thinking about local wood. Mizunara took decades of patient use before its character was understood and valued. A wood that tastes raw in a two year sample may tell a very different story at fifteen years. Anyone experimenting with an unusual cask needs records, matched controls and time.
Because the casks are expensive and scarce, Mizunara whiskies are often priced at a premium. Price alone does not tell you how much of that oak is in the glass. Your nose will tell you more than the marketing.
Tasting Mizunara for yourself
If you get the chance to taste a whisky matured or finished in Mizunara, compare it with one from the same producer aged in ex-bourbon casks. Nose both at the same strength and temperature. Look for sandalwood, incense, coconut and spice in the Mizunara glass that are absent or quieter in the other.
Add a few drops of water and nose again. Some of these aromas open up when the spirit is diluted. As always, taste slowly, keep water at hand and never drink and drive after tasting. Training your nose to pick out rare aromas like these is a skill that rewards practice with guidance.
Before your next bottle
Light a sandalwood agarbatti and smell the unlit end. Then smell a piece of plain wood and a little coconut. Fix those three aromas in your memory. When you next taste a whisky labelled Mizunara, you will have a reference ready.
Common questions
What is Mizunara oak?
A Japanese oak, Quercus mongolica var. crispula, used for whisky casks mainly in Japan.
What does Mizunara oak taste like in whisky?
Tasters commonly describe sandalwood, incense, coconut and spice, especially in whisky matured for a long time.
Why are Mizunara casks expensive?
The wood is scarce, slow to grow, often twisted and more prone to leaking, so making watertight casks is difficult and wasteful.
