As a black koji sweet potato shochu aged in unglazed clay pots for a minimum of 3 years, this promises to be a full bodied, richly flavored, absolutely decadent imo shochu. And does it ever deliver.
Shochu is a Japanese distilled spirit believed to have been learned from the Koreans during one of the Japanese occupations of the Korean penninsula. Shochu is known to have existed in Japan as far back as the 1500s though the exact date of its development on the island is unknown. It’s believed the Koreans learned from the Mongols who learned from the Arabs.
Shochu made from one (or more) of several grain options, koji, and water. It can be single or triple distilled. Single distillation (honkaku) is considered more appealing since it tends to be more flavorful and represents the traditional distillation method (honkaku means “authentic”). Multiple distillation (korui) tends to be reserved for the large mass produced shochu distillers.
There may be others, but these are what we’ve discovered so far.
Koji is a rice mold, or Aspergillus fungus. White (shiro), black (kuro), or yellow (ki) koji are used depending upon the choice of the the distiller. White koji tends to be most popular, because it results in a smooth, sweet taste. Black koji provides a richer, more complex flavor. Yellow koji, which is used in sake production, is much more delicate, but can result in a rich taste. The koji breaks the grains into sugars that can then be converted into alcohol by yeast.
Shochu distilleries take pride in the spring water they use from deep underground to cut their shochu distillate prior to bottling. This water lowers the alcohol content and if the water is high quality, provides a character unique to that particular distillery.