Chapter 3
How is honkaku shochu made?

Distilled beverages aren’t nearly as old as beer or wine, but their development is no less integral to the history of humankind. Originally used as medicinal remedies in the middle ages, and also for making perfumes and balms, it was not long before their full value became known to not only the scientists of Central Asia, but also the citizens. Many cultures worked with and developed the still technology that helped usher the advancement of both early pharmacology and general conduct disorderly.

The distillation techniques brought to southern Kyushu in the 16th century were adapted to fit the climate and natural resources of the region. At first, the most common starches used in shochu production were actually rice (kome) and barley (mugi). Barley has enjoyed enduring popularity over the centuries with its most recent boom taking place in the 1970s. More recently, however, a family of spuds has thrown its collective hat into the ring to vie for the shochu-loving public’s attention. This starch-packed vegetable from South America, the sweet potato (satsuma imo), arrived and was found to be perfectly suited to the Kyushu climate and terrain. The rest, as they say, is history, and Satsuma Shochu has since received appellation of origin protection from the WTO. Many other base ingredients are used, but these days distilleries sell four times as much sweet potato and barley shochu as rice shochu.

Shochu production techniques vary widely based both on the ingredients involved and the prerogatives of the head brewer (tōji), so let’s start with an in-depth but easy to understand exploration of how sweet potato shochu is typically produced. The production of honkaku shochu, no matter what the principal ingredient may be, generally follows this pattern:

 

1. Kōji preparation

2. First moromi fermentation

3. Second moromi fermentation

4. Distillation

5. Aging

6. Before bottling

a.  Dilution

b.  Filtration

7. Bottling

1. Kōji preparation (seigiku)

As mentioned in chapter two, Aspergillus mold, referred to here as kōji kin, is an essential part of the magic that allows fermentation to take place. In the creation of alcohol, whether it’s wine, beer or shochu, sugar reacts with yeast to create alcohol. For wine, grapes provide the sugar, and as mentioned in the last chapter the yeast is able to get started right away turning it into alcohol. However, beer requires an extra step before fermentation can take place. This is simplifying things immeasurably, but basically the grains are soaked and allowed to germinate, and then the sprouting process is quickly halted through the use of high temperatures so that the starches inside the grains can be easily modified into sugars with the help of some hot water (sorry, that’s liquor to you old-school brewer types). Grains that have undergone this process are known as ‘malt.’

There are, of course, other ways of converting starches into fermentable sugars. You may have heard of Peruvian corn beer, chicha. The starch-chopping enzymes in this case are found in human saliva, so the corn is chewed into small mushy cakes that are then left in the sun so the enzymes can do their work. Gross? Maybe at first, but it’s still sterile because the corn is boiled for at least an hour after that. In fact, nihonshu used to be made this way (kuchikami saké or “mouth-chewed alcohol”) as were many varieties of alcohol around the globe. Shochu is similar in that it needs a little help in converting starch into sugar. However, malted grains aren’t allowed in the production of shochu, and neither is spitting—figurative blood, sweat, and tears maybe, but definitely no saliva.

Malting and chewing are replaced by a starch and mold mixture called kōji. We’re discussing the production of potato shochu here, but more often than not potato shochu actually uses an entirely different base material to begin with: rice. The most common way to prepare ‘rice kōji’ is similar to the way they do it in the nihonshu world—kōji kin spores are sprinkled onto rice that has been washed, steamed, and then allowed to cool to about 35-40 degrees Celsius on a large table that has low, lined walls like a shallow pool. During the first dozen hours or so the rice is stirred regularly to make sure that the kōji kin has a chance to spread throughout the entire white, fluffy bed. A little more than half of a day later, this mixture is separated into rectangular wooden boxes (kōji buta), and these containers are carefully stacked in a checkerboard fashion so that the temperature of each small box of developing rice kōji can be closely monitored. The kōji is usually ready roughly 40-42 hours after the kōji kin spores first come in contact with the rice, and due to evaporation the grains of rice are quite hard at this point. While rice kōji is by far the most common type used to make shochu and awamori, barley kōji and sweet potato kōji are also popular with shochu consumers.

Covering a bed of handmade kōji.

Just to be clear, kōji kin are the mold spores, and kōji is rice (or another starch) that has kōji kin living on and inside of it. Please bear in mind that even though we’re focusing on kome (rice) kōji in this chapter, mugi (barley), imo (potato), and soba (buckwheat) kōji are routine as well. Regardless of the base starch involved, it is crucial that the kōji kin is provided an advantageous environment to spread throughout the starch source. To that end, distilleries build insulated kōji rooms that carefully regulate temperature and humidity so that the kōji kin can run rampant. At this early stage, the kōji kin provide enzymes as they work their way into the grains of rice. The enzymes, specifically Alpha-amylase and amyloglucosidase, work together to chop the long starch chains into shorter chunks and convert them into glucose. Glucose is basically just fuel when it comes to making shochu and awamori, so when the yeast is added during the next step of this process, it’s going to go bonkers at the biggest buffet of its life.

There are currently three main types of kōji kin used in kōji preparation. Listed from most to least commonly used in the shochu industry, the three types are white, black, and yellow kōji kin. Both white and black kōji kin are valued for the citric acid that they create in the mash (moromi), an essential defense against airborne bacteria and other nasties that can seriously foul up the delicate fermentation process, especially during the first couple of days. This is an even more pressing concern considering the hot and humid climate of the main production centers for shochu and awamori, so the citric acid is key. In most instances, white kōji kin can be counted on to soften and round the ingredients it touches. Black kōji kin, on the other hand, is loved for how it separates and highlights the flavors in the mash and adds impact to the final product. Many times you’ll notice a light sweetness and more memorable finish in shochu made with black kōji kin.

Yellow kōji kin, the type used to make most nihonshu, has found its way into some shochu distilleries even though it’s not a big fan of the hot and humid climate of southern Kyushu. Fortunately, advanced technology has made it much easier to control the temperatures within brewing and distilling facilities, so shochu consumers are able to enjoy an increasing number of labels that employ yellow kōji kin for help with fermentation. This type of mold affords a lighter and fruitier treatment of the mash constituents. However, as yellow kōji kin doesn’t produce citric acid like its white and black counterparts, distilleries must be exceedingly careful with their temperature management to prevent mash infection by wild yeast. When everything goes to plan, the result is fruit and flowers on the nose, and a prettier treatment of the other mash constituents.

This kōji is ready for the first fermentation.

Whatever the color, distilleries typically purchase kōji kin from specialty suppliers. The traditional method of kōji preparation described here used to be done completely by hand, but many distilleries have automated parts of the process. For example, it is incredibly common for bigger distilleries to use large metal drums or conveyor belts to expedite rice steaming. Others have made kōji preparation less time-consuming by opting for far larger boxes than the small and labor-intensive trays that were once the only way to go in the shochu world. Also, please keep in mind that the specifics of everything in this chapter can vary wildly according to the instincts and methods of the tōji and the ambitions of the distillery.

2. First moromi fermentation (ichiji shikomi)

Once the kōji kin has completely spread throughout the rice, the kōji is ready. Water and yeast are mixed with it to create the mash. The kōji is flush with glucose, so the yeast can quickly get to work creating alcohol. Depending on the size of the distillery, this starter fermentation will take place either in earthenware pots, often buried up to their necks in the distillery floor to help stabilize the temperature, or large metal vats. Most large-scale operations have opted for stainless steel because it’s more economical in terms of maintenance and manpower. For every 100 kg of kōji loaded into the preferred fermentation vessel, generally about 120 liters of water and between 100-300 ml of yeast are added. This limited stage of fermentation helps the yeast get warmed up before the main ingredient is added in the next fermentation phase. The fermented mash (moromi) is stirred frequently and typically bubbles away for five to eight days.

The bubbling moromi.

As the first fermentation is winding down, workers elsewhere in the distillery are busy preparing the truckloads of freshly-harvested sweet potatoes (imo) that have just arrived. They are washed and then have any blemishes or bruises carved out of them. This is one part of the production process that can’t be easily automated, and a large number of workers are generally required to lop the ends off of the spuds, clean them up, and remove damaged specimens from the conveyor belt. After the potatoes are relieved of their imperfections, they head to the steam drum for a nice, hot bath. The steamed potatoes are then transported to the shredder which chops the soggy spuds into small pieces that will be easier for the kōji kin and yeast to deal with in the second stage of fermentation.

Final spud inspection before steaming.

3. Second moromi fermentation (niji shikomi)

Now that the mold spores and yeast have been given a head start and multiplied enormously, they can easily handle the massive payload of crushed sweet potato that is added along with considerably more water. This is the second stage of fermentation, and most imo shochu distillers use roughly five times as much chopped potato as the amount of rice that was used to create the starter mash in the previous step. The formula can vary, of course, but this is generally how distilleries go about phasing in larger quantities of starch for the mold and yeast to mingle with. In large-scale distilleries the second stage of fermentation is then allowed to bubble away in large tanks for anywhere from eight to 10 days. In smaller outfits, the starter mash is divided amongst several pots before the extra water and potatoes are added.

It should be pointed out here that not all types of shochu follow this procedure in lock-step. Awamori, for example, uses only one stage of fermentation. Known as zenkōji shikomi, all of the kōji, water, and yeast are added to the fermentation vessel at the same time. In other words, awamori combines the two fermentation stages into one. Shochu used to be made this way as well, but these days two fermentation stages are used because of their ability to produce a healthy and vigorous ferment. However, this doesn’t hold for all types of shochu. Brown sugar shochu often includes a third stage. The first two moromi fermentations are technically the same as other types of shochu with brown sugar being added during the niji shikomi stage. However, the second stage is essentially split in two. Brown sugar is added to the bubbling moromi on separate occasions resulting in a third stage.

4. Distillation (jōryū)

Distillers don’t make shochu, they make kōji. Stills make shochu. Once fermentation has ceased, the distiller has a couple of choices for how to proceed. As you may have already guessed, this is yet another stage during which everything that is done to the shochu can have a drastic influence on the character of the final product. The now quiet mash is pumped into a still and this is where shochu is finally produced. Stills, of course, are amazingly complex instruments that enable the separation of components in a liquid. If ‘honkaku’ is what the distiller is planning to print on the label, then a pot still (often called an alembic in Europe) will be used to boil the finished moromi in batches. There are various types of pot still in use, but the basic principles remain the same. At sea level pure alcohol (ethanol) boils at just under 78.4 degrees Celsius (172° F), so the resulting vapor will contain a stronger concentration of alcohol than the moromi that is being heated at the bottom of the pot. The alcohol vapors rise and are collected in the cone at the top before being fed into a cooling column where they recondense before dripping into a collection container. And voila! We have shochu.

A pot still at Satsuma Musou Distillery in Kagoshima Prefecture.

If the distiller is aiming to make kōrui shochu, then a patent still will be used to create a distillate with as high a concentration of alcohol as possible. The first patent still was used in commercial alcohol production in Scotland in the early 1800’s where Irishman Aeneas Coffey is credited with bringing this form of continuous distillation to the masses, and it found widespread adoption around the world over the next century. The patent still arrived in Japan in 1895, and kōrui shochu was born in 1910.

Unlike continuous distillation, where the alcohol undergoes several distillation cycles in order to maximize its purity, batch distillation results in many of the esters from the flora used in the mash (sweet potato in this case) escaping from the still along with the alcohol. Just as in the distillation of some kinds of whiskey and other spirits such as Calvados Pays D’Auge AOC (which must be run through a pot still twice by law), this is a highly desirable outcome as it lends the final product more character and complexity. If the distillate is sent back into the pot a second or third time, then the product gradually becomes separated from the ingredients that were used to create it. A neutral alcohol is certainly the goal of kōrui shochu, vodka, and soju production, but this is decidedly not the case where honkaku shochu is concerned.

A pot still will begin by producing an ester-rich distillate called hanatare that is generally around 70% ABV, but this number tapers off as the run continues. The last part of the run is called suedare. At this point the ABV has fallen all the way to about 10% and exudes an organic acid-based aroma that adds depth and complexity to the distillate. The resulting unprocessed alcohol, or genshu, generally has an ABV in the mid to upper thirties although higher is certainly not uncommon. Insert your nostrils in the vicinity of the distillate and you’ll be treated to a bracing blend of oils, gases, and alcohol from the starches involved in the ferment. This raw bouquet is entirely due to the scientific and gut-level decisions made by the head distiller and the back-breaking work of everyone in the fields and distillery.

Obviously, the quality of the ingredients used during the kōji and moromi production stages have a profound effect on the taste of the final product because some of those flavors escape into the top of the still along with the vaporized alcohol. The rice kōji, sweet potato, yeast, and water all spent a considerable amount of time together before distillation, so it’s only natural that you will notice the complex interplay between them when taking a sip. Honkaku shochu prizes these aromas and flavors, and distilleries across Japan have labored for generations to perfect the conditions and techniques necessary to create the ideal moromi for distillation.

Most imo shochu are distilled at atmospheric pressure (jōatsu), but another way that a distiller can shape the flavors of the final product is to use a more modern still, one that can reduce the pressure inside (gen’atsu). Essentially, this is distillation in a vacuum, and alcohol will therefore boil at a far lower temperature. While alcohol vapors will start to waft to the top of a regular pot still at just over 78 degrees Celsius, reducing the pressure will cause evaporation at anywhere from 40 to 60 degrees. This is obviously a much softer boil, and less of the moromi will escape with the vaporized alcohol. The result is a milder distillate where the influence of the other ingredients in the mash is softer. The relatively recent introduction of low pressure distilling has allowed the shochu industry to experiment with more refined flavors and reach a whole new segment of the market. Awamori distilleries in Okinawa have also begun experimenting with low pressure distillation—while once unheard of, it’s becoming increasingly common to find awamori that blends distillate from the two types of pot still.

5. Aging (jukusei)

Another major decision that distillers must negotiate is choosing the best conditions for aging the genshu. One could go the way of wine or whiskey and age shochu in a carefully crafted wooden barrel (taru). Larger distilleries will often opt for large stainless steel containers (tanku) for this purpose, while family-owned establishments may go with old-school earthenware pots (kame). The choice here will bend the taste of the final product in a unique direction. I’ve seen long buildings lined up side by side at some distilleries with endless stacks of 450 liter casks. The most cavernous and mind-boggling that I’ve seen was at Kedogawa Shuzō in Kagoshima Prefecture, the makers of the internationally available and tasty Satsuma Shiranami line. The specifics are trade secrets, but they barrel-age their mugi shochu for a few years before bottling. Their Kannoko mugi develops a pseudo-whiskey coloration because of the barrel-aging, and the flavor is divine.

Inside the cooper’s workshop.

I’m a big fan of barrel-aged product, but earthenware pot-aged shochu is also delicious. Shochu is generally aged anywhere from one to three years, but it’s still relatively rare for it to be stored much longer than that. It’s often said that pot-aged shochu ages more quickly than whiskey thanks to the porous nature of the pots and the propensity for infrared rays to enter the vessel. At any rate, the rationale for aging shochu is the same as for other spirits; the harsher, brasher flavors will slowly diminish with time. These more aggressive flavors are released from shochu when gases separate from the liquid inside the conditioning vessel.

Conditioning tanks at Osuzuyama Distillery in Miyazaki Prefecture.

The large stainless steel tanks mentioned earlier are popular because they allow distilleries to age a massive volume of shochu at once. They also provide a highly stable environment for the aging process while imparting little to no extra flavors in the drink. Pot-aged shochu, on the other hand, often has a rounded or softened quality to it. This is attributed to the fact that air can permeate the small holes in the clay and interact with the sleeping shochu inside. If shochu is aged extensively in clay pots, it may be left with a light grey hue.

Oak barrels, on the other hand, have a much stronger influence on the shochu resting inside. The charred wood slats used to make the barrels are responsible for the aromas and color that ease their way into the genshu along with complex changes to the flavor profile. However, caramel coloring is never added to honkaku shochu as it is to some varieties of whiskey. One of the many restrictions imposed on the industry is that distillers are obliged to keep their shochu within just a few shades of perfectly clear. In other words, you’re not going to find a barrel-aged honkaku shochu that is darker than a light, golden straw color.

6. Before bottling

Dilution

Aged shochu undergoes a few more steps before finding its way into a bottle. The first step is blending (burendo or chōgō). The contents of the aging vessels are usually mixed together to ensure consistency. After that, water is added (warimizu) to the shochu to bring the ABV down to the desired level for bottling. If the shochu is destined for those little plastic jars that they sell in convenience stores across Japan, then it might get diluted down to 20% ABV. If it’s glass bottles and they’re headed to California, then 24% ABV will often be the target. For the domestic market, 25% ABV is most common, but 30% or more is not at all out of the question.

Filtration

Filtration (roka) is a magnificently underrated part of the production process even though it’s native to just about every brewing and distilling tradition out there. Generally employed either before or after the warimizu is added in another attempt to ensure consistency, filtration can be employed to further refine the flavor of the bottled product. The only caveat here is that white birch charcoal is not allowed at this stage; mass-produced vodka is known to use this medium in filtration, so its use is precluded in honkaku shochu production. However, other types of charcoal are acceptable, and filtration methods vary wildly in Japan as they do in the rest of the alcohol producing world.

Interestingly, the only time that you’ll notice filtration mentioned on the label is when the contents have not been filtered at all (muroka). Bottles are proudly labeled muroka because it’s a clear sign that the contents feature added character and depth. Depending on the substrate or method used, filtration is designed to remove impurities, off-flavors, chill haze, or color, so being able to say that a shochu is delicious even without filtration is certainly cause for some serious bragging. Indeed, muroka shochu are worth sampling wherever they may be found.

7. Bottling (bin’dzume)

After blending, dilution, and filtration, the shochu is pumped into the bottling machine where much of it will be sealed in 720 ml or 1800 ml bottles (bin) for the domestic market. The former is sometimes called a yon gō bin because it is four (yon) times the size of the gō decanters that are used to serve shochu and nihonshu in bars and restaurants. The 1.8 L (1.9 US quarts) bottles are called isshō bin and are a standard size in Japan. 10 times the size of a gō decanter, they are not ideal for home bars that lack space (like mine!). However, they look very impressive for special occasions, and in Japan they generally aren’t as expensive as you might expect them to be.

The bottling setups are as varied as the distilleries themselves with smaller outfits employing a much more hands-on approach to everything from controlling the flow of shochu into the bottle to applying the labels. Larger companies, as you can probably imagine, have this process completely automated. The vast majority of honkaku shochu in Japan retails for between 800 and 2,000 yen (US$8-20) for a 720 ml bottle. The sturdy isshō bin tend to be priced between 1,800 yen and 4,000 yen making it very affordable for a spirit.

I’ve tried to keep this brief overview of shochu production as simple as possible while including enough detail to illustrate how the process is unique. It goes without saying, however, that the best way to get a solid grasp of the concepts outlined in this chapter is to actually visit a shochu distillery. If you’re fortunate enough to be able to travel around Japan, try to include at least one distillery tour.