Charcoal Filtration in Sake-brewing

The concept of “filtering” in sake can be a slightly confusing one. One reason is that, at least in English, sake is filtered a couple of times.

For example, as most readers surely recall, sake is made by a process in which rice Kaseitan, or powdered active charcoaldissolves and its starch gets converted into sugar, and at the same time in the same tank a separate process is also taking place – that of yeast converting that sugar to alcohol. So starch-to-sugar and sugar-to-alcohol happen in parallel. What this also means is that when fermentation is complete, we still have a bunch of rice solids in the tank, components of the rice that could not be converted into sugar-then-alcohol.

So, that has to be filtered out. The mash is passed through a mesh of some sort – there are various methods – to hold back the solids and let the sake go through. So, it’s filtered. However, in the sake-brewing industry, a different word is used; this name for this process is translated as “squeezing” or “pressing.” And, in fact, many sake texts and articles in English also use the word pressing to talk about that first filtration of rice solids.

But there is a second filtration. After the sake has been pressed, and at some time during its maturation period, often it is mixed with a fine charcoal powder and/or diatomaceous earth, and after those particles settle out, it is passed through a series of paper filters to filter out the stuff they just put in.

The good news – and the reason they do this in the first place – is that these porous active charcoal particles absorb several things. These include elements that give a goldenrod color to sake, things that can contribute roughness to the flavor, and even some bacteria that would be detrimental to the stability of the sake.

Sometime about 40 to 50 years ago, some brewers began using this active charcoal, and the resulting clean and clear sake became popular. And as a result, most of the sake adopted the practice too. And it is a good one – it serves a purpose that leads to great sake. Of course, it can be overdone, and it can be done poorly. But when done right and in the proper measure, it is a good thing.

This step, by the way, is also a filtration, and this one is actually called as such by the brewing industry. Roka means filtration, and its opposite, muroka, means unfiltered in the sense that no powdered active charcoal was used.

Filtering machine, used to remove the just-added charcoalHowever, not all sake goes through this process. Not all sake needs to! It depends on the brewer, the method, the style of sake and even the water used. Some brew in a way that the sake comes out clear and clean, and simply do not need to do this step. Others prefer the goldenrod color deliberately avoid the charcoal. And others aim for a big, rougher, almost mineral-laced flavor and therefore omit this process.

There are also other ways to filter: ceramic filtration system and other solid-state mechanical filtration systems can be used. So charcoal is not the only way to go, but it does seem to be the most powerful way to remove color and roughness.

So, muroka refers to sake that does not go through charcoal filtration. Note, though, that this is not a legally-defined term, so that there can be and is some variance on the usage of the term. And we just have to deal with that. But I digress.

Bear in mind, though, this important point: Muroka is not unequivocally better than its charcoal filtered counterpart. It might seem that way to some, right? Natural. Unfiltered. Unsullied. And it is surely marketed that way by some. But it is not true. Sure, there is plenty of great muroka out there. If part of the deliberate design of the product, it often contributes to character and enjoyableness. But the charcoal-filtration process is a very precise, delicate and craftsmanship-laden one that contributes to better sake. So both are great for what they are.

This is one of those things that concerns me in the sense that a misunderstanding could Traditional Sakagura (sake brewery)hinder the growth of popularity of sake. It is like the thinking that says nama is better than pasteurized sake, or that aged is more special than young sake, or that junmai is better than non-junmai types (for any one of a myriad of silly reasons). Nama-sake (unpasteurized sake) is great! Aged sake can be fascinating and wonderful! And junmai-shu is without a doubt outstanding sake and an outstanding brewing philosophy! But these types are not at all unequivocally better than their (pasteurized, youthful, or added-alcohol) counterparts. Not at all.

And muroka sake is another one of these. Just because it says muroka on the label does not mean it is going to be … anything. It will not be better simply by virtue of that. It may not even be bigger or rougher. It might be – but nothing is guaranteed simply by virtue of the word muroka being present.

The best principle is of course to gather your own experience – try both and note your observations. You may end up preferring sake made using one method over sake made using the other. But chances are you will find that it depends much more on a dozen other things going on with the sake, and with your own preferences.

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The character for sake

Sake Meigara (Brand Names)

TenseiCurrently, there are about 1250 sakagura (sake breweries) licensed to brew sake in Japan (although not all of them are brewing actively). And, amongst these 1250 breweries are about 5,000 brand names, or “meigara.” Of course, not all of these are actively being used, but on the average each brewery has the rights to about five brand names.

But it wasn’t always this way. In fact, until about 600 years ago, there were no “meigara.” Sake was probably referred to by the name of the company (although admittedly branding was not such an advanced business concept back then), or even more likely the temple doing the brewing. The average citizen back then might have simply called it the local hooch, or Joe’s sake (or Shinnosuke’s sake, as it were).

Back in 1425 there were in total 342 sake brewers in Kyoto alone, many of these within Kyoto’s numerous temples. One of the most popular brews came from a temple named Nishi no Touin, and after time, its popularity led to a nickname born of affection. Next to the gate at the entrance grew a willow tree, and the locals began to refer to the place as “Yanagi no Sakaya,” or “The Willow Sake Brewer.”


The noren (a short traditional curtain that hangs at the entrance of shops inJapan that norencustomers part and duck under when entering) at the gate of Nishi no Touin bore a crest of six stars. Eventually, the brewing priests there began to emblazon this pattern on their wooden sake casks, along with the name “Yanagi-zake,” or “Willow Sake.” Thus, the first sake “meigara” was born.

Well, wouldn’t you know it, soon everybody had one of these meigara thingies. Taking names from “waka,” (traditional Japanese songs), or requesting aristocrats and priests to decide on a suitable moniker, brewers everywhere began to assign auspicious brand names to their sake. Some of the earliest ones on record include “Sazare-ishi” (Pebbles), “Mitarashi” (Holy Washing of Hands), and “Maitsuru” (Dancing Crane). In those days, obviously there were no enforceable trademark laws, and as such many of these names were copied and used in several places. Some of the more popular copied names included “Wakamidori” (The Green of Youth), “Otoha” (The Sound of Wings), and “Ariake” (Very Early Morning). Names were chosen for good luck and image, and often referred to auspicious entities in nature, like mountains, pine trees, flowers, and turtles.

Today, there are about 5,000 meigara in active usage. The names of these are written in kanji characters, the pictographs that comprise most of the written language. What is the single most common character in use in meigara today? That would be the character for mountain, pronounced either “yama” or “san.” Next on the list is “tsuru,” the character for crane (as in bird. I doubt any sake are named after construction equipment.).

Number three and four on the list are “masa” and “mune,” almost always seen together inChiyonosono Daiginjo the combination “masamune,” and have an interesting origin to them. There are countless sake that have “masamune” as the second half of their brand name, but the very first one is said to have been Sakura Masamune from Nada in Hyogo prefecture. Sakura Masamune is a very old, famous and prestigious brewer, and eons ago their founder visited a friend that was the head priest at a hermitage called Gensei-an. There, he looked up on a bookshelf and saw a book of scripture by the Rinzai sect Zen master Rinzai Masamune. In a moment of inspiration, he realized that the characters for “masamune” could also be read “seishu,” which is a homonym for the legal term for sake. And so, the first of hundreds of meigara bearing the term “masamune” was born.

Note, there is also a theory that the name was taken from a famous sword maker named Masamune, although the homonym reasoning remains the same in this story as well.

Other commonly used characters in the top ten include “kiku” (chrysanthemum), “o-” (big), “kin” (gold), “izumi” or “sen” (spring, as in water), “haku” (white), and “hana” (flower), in that order.

Why, by the way, would a kura have more than one brand name? There are several Yeast Starter Fermenting Awayreasons. They may have merged with another kura at one point in time in one of the several economic and wartime decimations of the sake industry that have occurred. Or, they may have created a new brand with a better image, especially when distribution channels allowed their sake to get to larger national markets, but kept the old brand name for the local fans.

The sake industry seems unique and can often be confusing since the name of the owner, the name of the company, and the brand name of the product are all very different. Confusing though it may be, at least there is a history to it!

Acidity in Sake


okan3The acidity – or rather, the acid content, of a sake is from commonly listed on sake labels in Japan. While this is less common overseas, and that might not change (no great loss, really), it is still worth knowing just what it is and what it reflects. But it is not exactly an intuitive indicator.

The numbers that express the san-do (acidity) are generally between about 1.0 and 2.0 or so. That is not a wide range, and most often the number seems to be about 1.1 or 1.2. The question is, 1.1 or 1.2 what?

Years ago, I began a quest to understand this. In turned out to be a monumental effort. I searched high and low, and asked almost everyone I could (outside of sake brewers themselves). Responses to this question placed to those that “should” know gave rise to whole plethora of silly answers. “Well,, they’re units! Yeah, units.” Percent, tenths of a percent, and parts per million were some other replies, all expressed with sincerity and confidence.

It was truly hard to find anyone that knew in the world outside of sake breweries. Not that it is going to make that much of a difference in the enjoyment of sake, but you think people would be curious. Finally, I went straight to the source, and found out from a brewer.

Momentarily digressing beyond the normal scope of this newsletter and delving into a mercifully short chemistry lesson, here’s the explanation.

The number expressing the san-do of a nihonshu is the number of milliliters of liquid sodium hydroxide needed to neutralize ten milliliters of sake. It is, in other words, measured by titration, just as it is in wine.

So, what does all that mean to the average taster? Basically the acidity (and to a degree, the amino acid content) can give you at least a vague idea of what a sake might taste like just from looking at the label.

In particular, the acidity and the nihonshu-do are very often used together to give a pre-purchase indication of what the flavor profile might be like. A good high acidity may increase the sense of dryness of a sake by lightening and spreading out the flavor. A low acid content, on the other hand, can help a sake to feel fuller and heavier, and increase a sense of sweetness.

There are so many things that affect the fragrance and taste of a sake that to allow the description to depend on two parameters is limiting at best. But you have to try.

Modern Methods of Measurement

To a slight degree, the various grades of sake can be vaguely generalized by typical acid Sake Yeast leads to aciditycontent. For example, ginjo-shu often has slightly lower acidity, being light and fruitier. Junmaishu usually has acidity levels slightly higher on the scale. Sake made with the kimoto or yamahai method of preparing the moto will have even higher amounts of acid present, and can be quite puckering. But as in all things sake, there is great overlap here.

But all this techno-babble is really only moderately useful, and only before you’ve tasted a sake. Once you’ve tasted it, you know all you need to know about acidity, sweet and dry, fullness of body and anything else.

Also, the method of measuring acid in sake is very similar to the methods for measuring acidity in wine: titration. And if one wanted to, one can express the total (almost) acidity of sake in terms of, for example, tartaric acid by multiplying the acidity number by 0.075. For comparison, sake has the equivalent of about 0.1 to 0.2 gms/100ml, comparted to an average of 0.5 to 0.9 gms/100ml in white wine.

The level of acidity will not always match presence of acidic flavor (known as the san-mi) in

Rare shot of rice when flowering (Psst! It's Yamada Nishiki!)

Rare shot of rice when flowering (Psst! It’s Yamada Nishiki!)

the sake, due to alcohol, water quality, type of rice and other factors. Some sake will taste sharp and cutting, when in fact the acidity is not that high chemically. The opposite can also be true.

In the end it’s just a number, more useful to brewers than to consumers. At the same time, paying attention to acidity, amino acid content and nihonshu-do can be fun. Doing so can give rise to lively discussion, and help us pay more attention to our perceptions