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Sake World Newsletter


April 2007



Color of Koji; Significance of Shinpaku

Color of Koji
Not three minutes will pass - max - into a conversation on sake without the word koji popping up. I have written about it countless times in this newsletter, and a quick search through the archives at will yield plenty more reading material.

As most readers doubtlessly recall, koji making is the heart of sake production. Koji is moldy rice, i.e. rice upon which and into which a mold, known as koji-kin (koji mold) has been propagated. As that mold grows into and onto the steamed rice that amounts to about 25 percent of all the rice in a batch of brew, it gives off enzymes that chop starch into sugar, allowing fermentation into alcohol. Koji does for sake what malting the barley and steeping it in warm water does for beer. Just how that moldy rice is prepared is everything in sake production. It will give you sweet sake, or dry sake, or clean sake, or stinky sake if one is not careful.

At the risk of being pedantic, in the ensuing discussion, let us remember that the word koji refers to rice that has successfully had the koji-kin propagated upon it. It does not refer to the mold itself. So now, let us look at that mold...

Koji mold is known in the scientific world as aspergillus oryzae. Got that? Uh... we'll just call it koji mold here. It is not terribly unlike the mold that grows on fruit and bread left laying around. And in fact it occurs naturally in the air everywhere. However, it is much more common in Asia, due in part to the overall higher humidity of the region. It can frequently be found growing on ears of rice in the fall.

And sake-brewing is not the only place one finds koji in Japan; it is used in making miso, shoyu (soy sauce) and more, including the indigenous beverages shochu and awamori. In fact, while we westerners may not be too familiar with the stuff, koji-making was once a business of its own here. Long ago, most people made their own miso at home, and they would buy ready-made koji to do that. There is even a neighborhood in Tokyo called Koji-machi, or "koji town," that long ago was the 'hood wherein many a koji producer could be found. Currently, koji mold spores are purchased in pure form by producers of sake, shoyu and miso from one of about half a dozen specialty producers that grow the mold in micro-biology-esque labs, strip off the spores, and ship it.

Even the slightly inquisitive will soon wonder, "Is there more than one strain of koji mold?" And indeed, yes, there are countless. But of far more importance than the actual strain of mold is the skill with which it is propagated on the rice, and whether or not it has been prepared in a way that is appropriate for the application, i.e. the grade of the sake and the stage of the production process.

Now, about that color. Koji komes in many kolors, and the type used to make sake is yellow. More correctly, after it has grown onto the rice, the kompleted koji looks yellowish in tint. (Note, within the family of yellow koji molds are countless strains as well.) So sake is made with yellow koji, or "ki-koji." Shochu, on the other hand, that distilled indigenous Japanese beverage made most commonly from rice, barley, or potatoes, typically is made using white koji, or "shiro-koji." Again, this describes is how the completed koji will look. And finally, awamori, that idiosyncratically scrumptious distilled beverage from Okinawa, is made using black koji, or "kuro-koji," which looks black when completed.

For the record, while the above outline governs the generalities, shochu in particular has some variation. Most shochu is made with white koji, but there is some made with yellow koji and some with black koji as well. What is the difference? Surely not just the color? Of course not. In short, the enzymes, acids and other ditties produced by the mold as it grows around the rice are different, and it is this - not aesthetics - that make it suitable or less so for the production of those respective products.

As one simple example, black koji gives off comparatively whacked amounts of citric acid, which would render sake, delicate as it is, totally undrinkable. Yet this not only gives awamori its distinctive earthiness, but it also provides it the ability to tolerate the higher temperatures of the near-tropical Okinawan climate in which it must be fermented, distilled, and aged. Conversely, and more relevantly, only yellow koji, provides the array of enzymes, acids and other goodies that can make good sake all that it is. 

As mentioned at the outset, you'll not get far into any discourse on sake before the word koji arises. Since all sake is made using ki-koji, the topic of koji color may not pop up much, but if it does, just remember: it's yellow.

*    *   *    *    *     *   *    *    *     *   *

For those of you interested in shochu and awamori, first of all: curse you. You should be drinking sake instead. But setting my own personal-preference-driven invective aside and coming from a more fair place in my heart that wishes all people peace in enjoying their own beverage of choice, should you ever be in Tokyo, check out the "Shochu Authority," a shochu-and awamori-only retailer located in the Tokyo Station building. It is located on the first floor, in the hallway that connects the Marunouchi and Yaesu sides of the station. I stopped in the other day. Not a drop of sake in sight. I felt *unclean.* Like, I needed a long shower, and immediately. But they do have an extraordinary selection of shochu and awamori and friendly, knowledgeable staff to help you should you want to try something new. So should your drinking preferences drive you to white or black koji, check out the Shochu Authority.

Significance of Shinpaku
The main raw materials of sake are rice and water, and rice is the only fermentable used in its production. And just as the grapes used to make good wine are significantly different from those bought at the supermarket, the rice used to make premium sake is significantly different from that which we find sitting under the fish in sushi, or in bowls in meals.

In truth, most sake - perhaps 75 percent of all produced - is actually made from regular table rice. And a lot of this is perfectly tasty sake. But when we meander into the realm of premium sake, especially ginjo, almost always it is made with proper sake rice, which is significantly different from regular table rice.

While there are many ways that sake rice differs from other types (size of the stalk, size of the grains, more starch, less fat and protein), the most talked about of them is surely the presence of a "shinpaku."

In proper sake rice, the higher-than-normal starch content is mostly concentrated in the center of the grains. Why is this so heart-warmingly special? Because we want to get at the starch, which will be converted to sugar and then into alcohol. But we don't want the fat and protein, which would lead to off-flavors and contribute rough elements to the sake. So with the starch neatly concentrated in the center, all we need to do is to mill away more and more of the outside of the grain, and by doing that we remove the fat and protein and leave only the starchy goodies behind.

That packet of starch in the center is called a "shinpaku." The word itself is written with the characters for "heart" and "white," and not surprisingly, when one looks at sake rice, you can clearly see that the heart of the grain is an opaque white, with everything around that being somewhat translucent. In regular rice, however, the color is uniform throughout since the starch, fat and protein are more mixed up and uniformly distributed.

A picture of milled sake rice, showing a visible shinpaku, can be found here:, under the rice milling section. 

Why does sake rice have the starch in the center, and fat and protein around that? Part of it is just the nature of those strains. But it also has to do with climate and growing conditions. Regions with hot days and cold nights are best for sake rice production, as the cold nights coerce the plant to send the starch to the center of the grains. In "bad years" for rice, seasons being too hot or too cold, too wet or too dry, or when the night and day temperatures had less variance, fewer grains will have a decent shinpaku.

What is interesting is that it is not the starch itself that makes the center of the grains white. What happens is that the starch molecules are round at the ends, and as they rush to get to the middle they don't interlock well, and they leave tiny air pockets between their ends. These diffuse light passing through, giving the opaque appearance we see.

Beyond different varieties or strains of rice, within each type there are grades based upon how well it was grown. This is a function of locale, climate, and skill of the producer. And one of the big points of assessment is the percentage of grains with a visible shinpaku. This is also one of the standards in the official assessment of sake rice versus table rice in general.

There are many more factors beyond the shinpaku and its size that are involved in qualifying good sake rice. But the shinpaku is the most visible, if not the most talked about.

Note, too, that one can make decent-to-good sake from regular rice. It takes a good toji and good tools, but just a few of the many examples of table rice from which decent sake is brewed are Koshihikari, Sasanishiki, the illustrious Kame no O. So one can indeed make decent sake from table rice. It's just easier to do so with real sake rice.

Finally, the question often arises, if a brewer is using table rice, why do they bother to mill down to 70 or 60 percent of the original size? If table rice has no shinpaku, isn't that meaningless and wasteful? The answer lies in the fact that in truth, all rice to some degree has more starch in the center and more fat and protein near the surface, whether or not this is manifested in a visible shinpaku. It is just that this is all more distinct in sake rice; *much* more starch is in the center, and *much* more of the fat and protein is near the outside of the grains. So more milling will have a positive effect on table rice as well when it is used in sake brewing, just not as pronounced as with good sake rice. As usual with sake-related things, it's all a tad vague.

Sake Events and Announcements
Thursday, May 10. The First Ginjo-shu Kyokai "Shin-shu Matsuri" Event. On the afternoon and evening of Thursday, May 10, the Ginjo-shu Kyoukai, those purveyors of good sake events, will hold their first ever Shin-shu Matsuri, or "New Sake Festival." It is, in short, a tasting that is a slightly toned down version of their usual fall fiesta tasting events. The event will be held from 14:30 to 16:30, and again from 18:00 to 20:00 (the two sessions will be identical) at the Diamond Hall room on the 12th floor of the Tokyo Kotsuu Kaikan, just out side of JR Yurakucho Station. Obviously, the event will feature the new, young sake of the 80-odd member breweries. This is a great opportunity to see what the soon-to-end sake brewing season has yielded. The cost is a mere 2000 yen when paid for in advance, 2500 yen day of show. Note, though, that unlike their autumn event, guests will not receive a bottle of sake when leaving. This is to keep costs down and hopefully interest high, and the very accessible location should help that as well. Those interested in attending can send your name, address, and telephone number to (in Japanese if possible, but they will likely figure it out), or fax it to 03-3378-1232. They will then send you an invitation with a payment slip for use at a local post office. Or you can just bite the bullet, pay \500 more, and drop in at the event. As a new direction in events for the Ginjo-shu Kyokai, this one will certainly be worth a visit.

Links to Sake Book Info and Archives
More information on the following topics can be found at

  • Sake Homebrewing
  • Books on Sake
  • Information on the archives of this newsletter
  • Genereal information related to this publication

All material Copyright, John Gauntner & Sake World Inc.
1-4-4 Jomyoji, Kamakura-shi, Kanagawa-ken, Japan, 243-0003


Copyright 1999

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