By Johnnie Stroud, owner of Saké Nomi

We often hear customers profess their belief that “all bad saké is served hot and all good saké is served chilled.”  Like most everything else in the saké world, it’s not that simple. But this kind of thinking is understandable, since many restaurants in the U.S. serve a lower grade “house” saké very hot.
The custom of heating saké in Japan actually originated in China and was tied to the belief that it was healthier to take food and drink warm, at a temperature close to one’s body temperature. Back before rice-milling technology was very advanced, the saké was a lot less refined than it is today, and warming it up certainly took some of the rough edges off.  Warming the saké was very much the norm, and many saké pubs employed a person whose sole duty it was to warm the saké and to know each regular customer’s preferred temperature.
While we suggest most premium saké be served slightly chilled, all saké show different qualities at different temperatures, and there’s no denying the pleasant warming sensation of gently heated saké warmed to just the right temperature.  In the end, there are no strict rules as to which saké you can warm, and it all comes down to one’s personal preference.
However, not all saké will benefit from warming, so the combination of the right saké correctly warmed to the right temperature can be tricky. Because they are brewed with rice that is not as highly milled as the other premium grades and can be a little heartier and sturdier, slightly sweet futsu-shu (“regular”), honjozo and junmai grades often make the best candidates for warming.
A couple styles of saké that often transform in interesting, delicious ways when heated are the kimoto and yamahai varieties, which are brewed using more labor-intensive, old-fashioned methods, and which, unlike the majority of saké produced, do not include the introduction of lactic acid in the beginning of the brewing process.
In both these brewing methods, the lactic acid eventually develops naturally and sterilizes the moto, or seed batch, but before it does, “wild” airborne bacteria are introduced to the sake. They can leave traces of funky, acidic flavor behind.  These kinds of flavors can mellow and sometimes turn almost buttery when the saké is gently warmed.
When warming saké at home, the biggest mistake to avoid is making the saké so hot that you lose all the flavors and aromas that the brewers worked so hard to cultivate during the saké’s long, cold fermentation.
You can use a microwave oven to heat your saké.. However, it can be difficult to heat it evenly using this method.  Though it takes more time, it’s probably better and gentler on the saké to heat a ceramic tokkuri, or decanter of saké, in a pan of hot water on the stove.
At Saké Nomi, we take the guesswork out of the wonderful seasonal treat that is kanzake (warm saké) by handpicking saké we think are well-suited to warming. And to ensure that we bring it to the correct temperature, we use a kansuke, a special machine (a kind of hot water “bath”) imported from Japan, made exclusively for the purpose of heating saké.