Ayakiku Sanuki Olive: Sake Brewed With a Yeast Found in Olives

New on the bottle list at $85: Ayakiku Sanuki Olive Junmai, from Kagawa. It is brewed with a yeast that was isolated from olives, which sounds like a gimmick and is not.

Kagawa Is Olive Country

Kagawa is the smallest prefecture in Japan and it grows almost all of the country's olives, on Shodoshima and the coast around it. They have been at it for over a century, since a government trial that mostly failed everywhere else and took hold there.

Olives are the thing Kagawa is known for. So when the prefecture went looking for a brewing yeast to call its own, it went looking in the olives.

Four Years to Find One

Sanuki olive yeast was isolated in 2019, after four years of work by the prefecture's sake brewers association together with its fermentation research institute.

Four years sounds excessive until you know what the job is. Wild yeast is everywhere, on every fruit skin, and almost none of it can brew sake. A strain has to survive a low-temperature ferment, tolerate rising alcohol, produce the right aromatic compounds and none of the wrong ones, and do it the same way every time. You are not finding a yeast, you are screening thousands and hoping one is usable.

Ayakiku started brewing with it the year it was found.

It Does Not Taste Like Olives

This is the part worth understanding, and it is the same lesson as the buckwheat-flower yeast in our post on Unkai.

A yeast does not carry the flavour of whatever it was found on. It is not an ingredient. What it carries is its own metabolism: which esters it throws during fermentation, how much acid it produces, how it behaves as the alcohol climbs. Where it was collected is a biography, not a flavour note.

So what this yeast gives is passionfruit and lychee, a bright tropical character with a crisp acidity underneath it. None of that is olive and none of it is rice. It is the yeast, and if you had been told it came from a flower you would believe that too.

Everything From One Prefecture

The rest of the bottle keeps the theme. Ooseto, a Kagawa rice variety, milled to 60%. Water from the underground flow off the Asan mountains. The olive yeast.

Rice, water and yeast all from the same prefecture is a harder constraint than it sounds. Most breweries buy Yamada Nishiki from Hyogo because it is the best sake rice there is, and use a yeast from the national association's library. Doing it entirely locally means accepting whatever your own rice and your own yeast actually give you.

It has done well on that basis, taking a bronze at the International Wine Challenge in 2021 and a gold at CINVE in Spain.

How to Drink It

Cold, in something with a bit of a bowl to it so the aromatics have room. This is a sake where the nose is doing a lot of the work and a straight-sided cup wastes it.

Do not warm this one. The tropical esters are the point and heat scatters them.

It goes with lighter things: sashimi, handrolls, grilled fish, anything with citrus on it. It has enough acidity to handle fried food too, though it is a waste next to anything as loud as our karaage.

If you usually order the dry end of the sake list, this is the opposite pole, and the two are worth tasting against each other.