Welcome to an ongoing series of in-depth posts about all of the variables and choices you have while preparing hot sake! Despite being a simple process (heating sake), there are tons of variables that determine the final outcome of the sake. You can think of it like cooking - a single steak will taste completely different based on the cooking method, cookware, temperature, and skill of the chef. The same applies to sake!

Chirori, or the cup-shaped vessels used to heat sake, come in a wide variety of materials. The most common are tin, copper, aluminum, ceramic, and glass. Which you choose has a profound impact on the final sake!

Tin

Tin chirori have a relatively high thermal conductivity and typically make the sake more soft, rounded, and mellow. It highlights the more “deep” notes of caramel, chocolate, sweetness, and umami from sake and minimizes the “brighter” flavors. It can mellow high-acid sakes and turn your funky, umami sakes into a pure umami bomb, similar to a miso soup.

I’ve found that tin is best used for a sake that is already on the very umami, funky, rice-forward end of the spectrum. It melds all of the complexity together and highlights what makes the sake special while taming the aggressive funky notes that may come out using other methods.

Copper

Copper chirori have extremely high thermal conductivity. Sake heated in a copper chirori comes to temperature very quickly. You can think of it as quickly shocking the sake instead of gradually and gently bringing it up to temperature.

As a result, sakes warmed in copper tend to be very bright and acidic. It is great for lighter sakes and ones with a touch of fruity complexity to them. Copper preserves those fruity notes and the bright acidity highlights them as well. Extremely umami/funky sakes do not work particularly well in copper, as the balance is thrown off and they can taste too sharp.

One important thing to note is to be very careful with copper chirori, as the sake can heat so quickly that it develops a “burnt metal” taste.

Aluminum

Aluminum chirori are the very thin, cheap, mass-produced ones you find everywhere. Aluminum has a medium level of thermal conductivity, but due to how thin they are, they conduct heat very quickly as well.

Honestly, I have not had a single sake that I’ve preferred in aluminum. They all have a harsh, almost metallic taste to them. The sake is neither rounded and soft like in tin or bright like in copper, but just harsh, as the flavors seem to separate instead of come together.

Overall, I have not found a use for an aluminum chirori, despite them being ubiquitous in stores and online (solely due to how cheap they are).

Ceramic

Ceramic vessels have the lowest heat transfer. They take an extremely long time to heat the sake and therefore provide a much more gentler end product. The resulting sake tastes more similar to the flavor profile as the same bottle served cold.

This is a great method for sakes that have a lot of subtle characteristic that may be lost with the other methods. It can preserve some “fresh” flavors like fruit, powdered sugar, or rice powder. If you have a sake that you love cold but may think it’s too subtle to be served warm, I suggest trying it in ceramic.

In-Bottle

A lot of restaurants or tastings may warm the whole bottle. This is mainly due for ease of use, not for a desired end-result. There are a couple downsides to this method that are worth pointing out. The first is that you have to heat the entire bottle, so if it’s not all served within a relatively short time period, the sake will become “cooked” as it stays heated for a long period of time.

Second, the shape of a bottle means there is less airflow. A lot of the alcohol fumes and other flavors will stay trapped in the sake instead of being lost into the air, potentially resulting in a more harsh sake.

Otherwise, this method is most similar to the ceramic method, described above. There is minimal impact on the hot sake compared to fresh, but I’d recommend using a ceramic tokkuri instead.

So, what’s the best?

There isn’t one! Mix and match and experiment with warming sake in each of the vessels described above. As a general guideline:

Tin for funky, umami-rich sakes
Copper for brighter, fruitier, acidic sakes
Ceramic for more delicate sakes that you enjoy cold

Okay, but I’m not buying all those - what do I get?

Fair! If you’re looking to buy your first vessel for warming sake, I’d recommend a ceramic tokkuri. You can find them for cheap and they will work well for almost all sakes out there.

Why is this the case?

A lot of studies have been done on the differences between chirori materials and the resulting sake, and they do show that there is a marked difference in the sake. We sake nerds are not making this up!

A lot of the difference can be attributed to the thermal conductivity of the material itself. Copper (303W/(m-K) conducts heat extremely quickly, tin (66.6 W/m-K) less so, and ceramic (3.8 W/m-K) even less. In cooking analogy, copper is more like searing a steak while ceramic is more like gently poaching it. You can see why you’d want to use one method rather than the other.

And yet, aside from thermal conductivity, most studies indicate there is something else going on. The sake reacts with the actual material for non-inert chirori (such as copper, tin, and aluminum), but doesn’t with inert materials (such as glass and ceramic). Therefore, the choice you make goes beyond how fast the sake is heated.

Hot Sake Basics #1 - Chirori

Tin