Fun with Koshu

Koshu, or aged sake, is a tricky thing. It’s a big, popular topic right now, and everyone is talking about how amazing it can be, but it’s also kind of a mixed bag. It can be funky, and off-putting, and sometimes downright undrinkable. One I tried was described as having notes of soy sauce, earth, and bleue cheese. And that was the recommendation!

At the same time, well-made sake that is properly aged in a cool, dark place, can be a very pleasant drink. The flavors tend to morph from the familiar sake blends of sweetness, umami, and sourness into something more complex and nuanced. The pursuit of koshu definitely has the feel of a jaded aesthete kind of hobby, but given that some very nice koshu (like Gokyo’s) is essentially the same price as any other bottle of sake, it’s not exactly idle rich type of stuff.

But it is the “thing” right now, and it seems whenever I’m in sake drinking company the topic comes up. At a recent session at my local sake-specialty bar, the owner joined us for a few drinks, and suddenly seemed like he wanted to impress us, so he started breaking out the rare, old koshu.

First up was a bottle of Kotobuki from Nakashimaya Shuzojo, a very local brewer. This particular bottle was brewed about 15 years ago, apparently, and is smooth as velvet. It seems to have achieved a perfect balance of umami and sweet that doesn’t cloy at all, but still carries a full, heavy load of flavor. Excellent stuff.

The next big splash came from a 3 year comparison set. This sake is, I believe, called Nadeshiko (the kanji is 撫柳 so it’s a weird one). It’s from Umenishiki Shuzo in Aichi prefecture, and the owner had three bottles of this limited edition daiginjo.

Before we move on to the taste testing, that term Shinsei 真精 should stand out–it did to me. It was the first time I’d ever seen it! The term is important, especially since it’s the reason these bottle go for about $300 each. Shinsei refers to the way that the seimaibuai is measured for rice.

For a quick recap: seimaibuai refers to the amount of rice that remains after milling, so a seimaibuai of 40% means that 40% of the rice grain should remain after milling. The way this is usually measured is by weight: the rice is milled until 40% of the original weight of the rice is left. (I.e. you start with 1000 kilos and mill until you have 400 kilos left). However, this will inevitably mean that there is variation in the actual rice grains. Some will be milled down more than 40%, some will be much larger. It’s not a super precise science.

However, Shinsei tries to eliminate that variation as much as possible. Instead of figuring the seimaibuai by the whole load, the maker will calculate by measuring the 千粒重 senryuju, or “thousand grain weight.” Yes, that means they will measure out small batches, count out 1000 grains of rice, and compare the weight before and after milling. It’s an insanely labor intensive process, and obviously very rare, but there it is. Some madmen do it. And this is the sake that results.

The owner had a bottle from 2016, 2017, and 2018. This isn’t especially old sake, but it’s an incredibly valuable chance to see the same style of sake made by the same person in the same exacting process across three different years–and they were different! Obviously so. The concensus was that the 2017 was the best of the lot. It had a much more interesting flavor that worked variation into a smooth, balanced drink. The 2018 felt a little raw and leaned too heavily to the umami, while the 2016 seemed to lack something in comparison to the 2017. To be clear: none of these sakes were in any way bad. They were, frankly, excellent. But if we compare, we compare, and that’s how it fell.