Shochu is a clear, distilled Japanese beverage with an alcohol content of about 25 to 42%.
It can be made from short-grain Japanese rice, barley, sweet potatoes or buckwheat. Some novelty ones are based on brown sugar, foxtail millet, pumpkin, green pepper, chestnuts, shiso leaf or even milk. About 53% is made, though, from barley, and about 21% from sweet potato.  Much of the barley is imported from countries such as Australia, who grow it with an eye to the Shochu market to make sure they can supply the grades needed.
Koji mould (“aspergillus oryzae”) is used in the fermenting — either yellow koji, white koji or black koji. The koji will be either rice-based or barley-based. The mould breaks down starches into sugars. Barley is pearled first to get rid of the outer layer that would hinder the working of the koji on it.
After the koji has produced sugars out of the Shochu’s base ingredients, then yeast is added to ferment it, then the distillation begins.
There are two main types of Shochu, based on how it was distilled. The most “authentic” or at least the oldest kind is called Otsu-rui or Honkaku. “Otsu” means “second”: this grade used to be classed as “second grade”, because it was less pure, which caused consumers to look down on it. It is single distilled; it retains more of the personality of the main ingredient. The distillation can be at normal pressure, or forced. More personality can come through if the distillation is done at normal pressure.
The second type of Shochu has several distillations. This method dates from about 1911, and got legally acknowledged in 1949. It is called “Kou-rui” Shochu. “Ko” means first grade, as in purer. It is, however, more likely to use several main ingredients and has less taste character. This makes it smoother, and better for use as a mix.
The first of a year’s batch of Shochu is called “Shinshu” (new Shochu) and is sold in November.
Though all Shochu is usually aged at least a few months before being sold, when Shochu is aged beyond that, it’s called “Kusu.” It is usually sold in blended amounts of aged Shochu. If the label says 51% aged three years, the remaining 49% of the Shochu in the bottle may have been new that year.
A popular version of Shochu is “awamori,” made in Okinawa from long-grain indica rice imported from Thailand. The knowledge to make this probably came from Thailand as well. Black koji mould is used to ferment the rice. It is distilled once. Most awamori has some water added back in to lower the alcohol content to the 25 to 30 % range, though it can be found at 43%. As of April 1983, makers of awamori got to label their product as “Authentic Awamori.” Prior to that, they had to say “Shochu, Second Class.”
When Shochu is made from sweet potato, it is called “imo-jochu.” It is a specialty of Kagoshima Prefecture; no sake is made there at all. In fact, if you ask for sake, you get Shochu. The sweet potatoes are used within a few days of being dug up. It is aged at least a few months before sold.
Generally, Shochu made from rice will be smoother and lighter tasting; ones made from sweet potato stronger. Rice Shochu is called “kome-jochu.”
Honkaku, the single distilled Shochu, is usually drunk straight, though ice or water can be added. When served “on the rocks”, it’s called “shochu rokku.” When served mixed with water, a typical ratio is 60% water, 40% Shochu. The water can be hot or cold.
Kou-rui, the repeatedly-distilled Shochu, can be mixed with a juice (such as grapefruit, orange or peach), or Oolong tea. It is used in mixed drinks such as “Chu-Hai” (meaning “”shōchū highball”); these are sold even canned out of vending machines.
Shochu is more popular in Western Japan than Eastern. These western regions are warmer. Cooler parts of Japan were better for sake, which is brewed, not distilled.
The Korean version is called soju — and in fact, Koreans may have made it before the Japanese.
The first written record of Shochu in Japan dates from the 1500s on Kyushu island in Kagoshima Prefecture. This is graffiti by a workman, saying, “I was disappointed that the manager didn’t offer us a glass of shochu for all the hard work we’ve done for his shrine.”
Some theorize that knowledge of making Shochu came straight from Thailand, others say it came from China via Korea.
 Gray, Blake W. Move over sake, here’s shochu. San Francisco, California: San Francisco Chronicle. 12 August 2004.
Sake World Sake e-Newsletter. Issue #66, 1 April 2005.
Washington, Jennifer Marie et al. Pearling and SKCS Analysis of Australian Barley for the Asian Food Market. Grains Research and Development Council. Barley Technical / Cereal Chemistry 2003, conference proceedings : a joint meeting for the 11th Australian Barley Symposium and the 53rd Australian Cereal Chemistry Conference, 7-10 September 2003 : 5p.