The Storyof SakeFeaturedarticleSake (Seishu)

History............................................................ 1
How is sake made........................................... 2
Product information........................................ 6
How to evaluate and enjoy sake...................... 8

Sake is a traditional alcoholic beverage in Japan. It is
made through fermentation, like beer and wine. Sake ismade from rice, a staple food in Japan. It is an integral
part of the Japanese lifestyle and culture. In recent years,
Japanese cuisine is becoming more popular internationally.
Accordingly, increasing number of people enjoy sake,
which goes well with Japanese cuisine, all over the world.
The processes and methods of making sake are quite
a bit more complicated than those for making wine andbeer. Nowadays, though, sake production techniques havebeen largely clarified by science. The traditional skills ofchief sake makers, called toji , as well as modern scientificknowledge, have made it possible to produce varieties ofhigh quality sake.

A traditional sake brewery

NRIB(National
Research Instituteof Brewing)
January 2014

History

It is not exactly known just when people began making
sake in Japan. However, it is believed that an alchoholic
beverage made from rice was already being made in the Yayoi
period (300 BC-250 AD) when rice cultivation was broughtfrom China to Japan. It was during the last half of the Nara
period (710-794) when the methods of rice growing became
stable. A special organization called Sake-no-Tsukasa wasestablished to produce sake for the Imperial Court. During
the Heian period (794-1185), sake was made in temples
and shrines, as well as among the people. Sake breweries
appeared in the Muromachi period (1333-1573). Because ofthis, the Muromachi Shogunate started charging taxes on sakeproduction, as a source of revenue for the government. In thelast half of the 16th century, people started to polish the ricegrains for sake making, and to press the fermentation mash to
separate the sake. A heat sterilization (pasteurization) process
called hiire was also invented during that period. By this time,
the technique to make large wooden tubs had been developed,
which enabled sake breweries to make and store a large
volume of sake at one time.
Manufacturing sake became a thriving industry during theEdo period (1603-1868). During that period, they devised atechnique to add distilled alcohol to sake in order to adjust theflavor and preserve it from bacterial contamination.
In 1904, the National Research Institute of Brewing wasestablished in the Ministry of Finance. It is a unique national
research institute foralcoholic beverages
in Japan that conducts
scientific research on sakemaking and develops newtechnology and techniques
for sake making.
From ancient times,
sake was regarded as a
special beverage made fromprecious rice. People dranksake on special occasions,
Sakabayashi or Sugidama
such as festivals, marriages,
Sake breweries used to hang a large balland funerals. Now, we can made of cedar twigs (Sakabayashi ) at theirenjoy sake any day as a tool entrance. This announced that fresh sakemade. When the fresh green needles
for communication among was
turned brown, that was the sign that thepeople.
new sake was ready to drink.
01

Brownrice
science ofsake making
How is sake made? The
Sake, just like wine and beer, is made through thefermentation of yeast. Fermentation is the process whereby
yeast (a kind of microbes) produces alcohol and CO2 fromsugar.
Sake is made from rice, koji , and water. Alcohol may also
be added. Here is an outline of the process of making sake.

Brown
rice

Rice
polishingPressing

Sake
cakes

Sake
Rice washingand soaking

rate. In order to obtain 1 kg of white rice with 70% of
rice-polishing rate, we need 1.4 kg of brown rice. Whenmaking a special refined sake (daiginjo-shu ), 50% or moreof the rice is polished away. Some of the highest-quality
daiginjo-shu is made from rice with 30% of rice-polishingrate. It may seem wasteful topolish away 70% of the rice.
However, rice polishing is oneof the most important steps to
produce great sake with finearoma and elegant taste.

Farmentation
starterHeatsterilization

Fermentation
mash

Storage(aging)Bottling

How to make sake

Rice

Sake is an alcoholic beverage made from rice. There
are special varieties of sake rice that are suitable for sakemaking, called shuzo-kotekimai , just as wine is made fromwine grapes.

Yamadanishiki , a variety of sake rice

Flowers of
Yamadanishiki

Fine polished white rice, not brown rice, is used to makesake. Rice contains protein. The koji enzymes break down
the protein to amino acids and peptides. These compounds
provide umami (savory taste). However, if there are toomuch of amino acids and peptides, then the taste will
become too heavy. It is known that the oil in the rice grains
prevents the development of a fruity aroma. Therefore,sake breweries polish off the outer layer of the rice grains,
the bran, which contains a lot of protein and oil, so that thesake will develop its special aroma. Table rice is polished
to remove about 10% of the outer layer. For rice used forsake making, 30% of the grain is polished away, whichmeans that 70% is left. The proportion of rice remaining,
not the proportion removed, is called the rice-polishing02

Rice
washingand soaking

Filtration

Rice
steaming

Koji
makingRicepolishing

Brown
rice

70%
polishingrate40%
polishingrate

Automated rice-polishing
Polishing rice takes 1 to 4 days machine. The experience ofdepending on the rice-polishing sake brewers was converted
to computerized data to control
rate.
this machine.

First, the rice bran powder is washed out of the rice. Then,the grain is soaked in water so that it absorbs adequate
moisture. Then the rice is steamed. Sake is made during thewinter, and the workers in sake breweries have to work in
the cold season using cold water. Therefore, washing rice
is a very arduous job. The technique for making the grain
absorb moisture varies with the rice-polishing rate andvariety of rice. The soaked rice is drained and covered witha cloth overnight. The next day, the rice grains are sent to
the next step, steaming.

Manual rice washing

An automatic rice washing andsoaking machine

Either a traditional steamer or an automatic steamer
is used for the steaming process. Steaming, as well as
cooking, makes the rice starch easier for the koji enzyme tobreak down. Unlike table rice which are cooked in water,
steamed rice is still quite firm. The most important factor
to make koji and a fermentation mash is to ensure that thesteamed rice grains are separated from each other, and notstuck together. Some table rice varieties for eating, suchas Koshihikari , are sticky and make a thick ball of grain.
Therefore, these varieties are not suitable for making sake.
Of all the rice that used for sake making, 15 to 25% is used
for koji making. The rest of rice is steamed and added to afermentation starter and a fermentation mash.

Ricesteaming

Koji making

Fermentation

KoshikiA traditional steamer

An automatic steamer

Pressing

Sake

The Storyof Sake

The first step in making koji is to cool down the steamed
rice, and bring it into a koji room. Then, the rice is spreadout on a long table called toko , and spores of koji mold arescattered over it. Then, the mass is mixed well so that thespores adhere evenly to the steamed rice. After that, the riceis heaped up and covered with cloth to keep the temperatureand humidity of rice constant. The scattered spores
germinate and extend their hyphae. During this process,the temperature of koji rises from the heat generated by the
koji ’s metabolism. In order to keep a suitable temperature,moisture, and the growth of hyphae uniformly, the koji ismixed and the pile is spread out again.

The toji (the chief sake maker) Workers are carefully spreading
scatters koji spores onto rice in a out newly made koji .
koji -making room at a temperatureapproximately 30˚C.

As time goes by, white areas called haze extend across thesurfaces of the rice. Approximately two days after the rice isplaced in the koji -making room, the koji making is finished.
1st day

2nd day

Areas where the hyphae of kojimold grow become white.

After approximately two days,
the koji mold completely covers
the steamed rice.

Freshly-steamed rice

Steamed rice being cooled and transported
automatically on a conveyor belt

Koji

Koji mold (a variety of Aspergillus ) is called the national
fungi of Japan. Koji is used for making a variety of
traditional Japanese foods. Beside sake, koji is used to makeshochu (Japanese liquor),
soy sauce, miso , and vinegar.
Strains of koji have beencommercialized since the
Muromachi period (13331573), which is much earlier
than yeast strains.
Koji spores

The koji extends hyphae not only on the rice, but also
into the rice grains. While the koji mold is growing on thesteamed rice, it produces enzymes. Although the enzymes
cannot be seen, they have a very important role in the sakemaking. The enzymes from the koji convert the starch in
the rice into sugar.
Yeast needs sugar to make alcohol. Starch has longer
molecules made of sugar and cannot be directly converted
to alcohol by yeast.
That is, yeast does nothave an enzyme todigest starch. Whenthe koji is added
to the fermentation
mash, its enzymes
convert the starch tosugar. The yeast canthen produce alcohol The koji enzymes (as shown in the beakerfrom that sugar. Koji on the right) convert the starch in steamed
to sugar, and the fermentation masha n d y e a s t m a k e a rice
becomes liquefied. The left beaker does not
great team!
contain koji .
03

Brownrice

Ricepolishing

How is sake made? sake making

The science of

Water

Water is indispensable for sake making. Sake contains
approximately 80% of water.
Besides being used to make a fermentation mash, water isalso used to wash and to soak the rice. Sake making needs
approximately 10 times as much water as rice. The qualityof the water for sake making is very important.
Iron is the most unfavorable mineral in water. If sakecontains too much iron, it has a reddish brown color, andits taste and aroma are unpleasant. The iron concentrationin water used for sake making must be less than 0.02
ppm, which is lower than water quality standards for tap
water (0.3 ppm orless). Fortunately,
there are many
excellent water
sources all overJapan that fulfill thisrequirement. Where
excellent water
sources exist, youwill find many sakebreweries, such asat Nada in Kobe andFushimi in Kyoto.
They are designatedas among the 100
best water resourcesby the Ministry of
the Environment.
Fushimi in Kyoto
In a shrine in Fushimi, Kyoto, there is afamous spring of excellent water. There
are many sake breweries in Fushimi using
this wealth of good quality water.

Yeast

Yeast is used for producing many foods, such as breadand soy sauce. Yeast, which makes alcohol, is very
important for sake making.
Where do we find yeasts in nature? Yeast likes sweetthings, like fruits and flowers. Many types of yeast growon the skin of grapes when they are injured. Really,
yeast lives almost
everywhere, in the sea,
mountains, rivers, andsoil . . . throughout
the nature. Yeast lives
on plants, such as rice
plants, and also insake breweries. They
are called wild yeast.
Yeast

Before the pure culture method of yeast was developedin the 19th century, sake was made through natural
fermentation using wild yeast. Lambic beer and naturally
fermented wine are still made with wild yeast, eventhough it is uncommon for sake making. Some wild
yeasts produce unfavorable smells, like paint thinner orvinegar. Wild yeasts usually have low ability to produce
alcohol and is not suitable for sake making.
Nowadays, most sake breweries use reliable sake yeast
specially selected from wild yeast. Using sake yeast
ensures the stable production of high quality sake.
It was 1895 when Dr. Kikuji Yabe isolated sake yeast
from a fermentation
mash for the first time.
Then, the Brewing
Society of Japan
started distributing thisselected sake yeast to
sake breweries all overJapan. Different sakeyeast strains provide
different aromas andtastes. Sake breweries
use appropriate yeast Kyokai yeast (yeast distributed by
the Brewing Society of Japan)
strains for their sake.

Shubo (Fermentation starter)

In order to cultivate the large amount of yeast required
for fermentation mash, fermentation starter is prepared. It
is also called moto (meaning ‘source’ in Japanese) as thisis the original source of sake fermentation. First, water,
koji , and steamed rice are put into a tank, and cultured
yeast is added. Generally, lactic acid must be added to thefermentation starter. Lactic acid suppresses the growthof harmful bacteria that might produce unpleasant smell
and taste. In the case of traditional types of fermentation
starter, called kimoto or yamahai , lactic acid bacteria growfirst and produce lactic acid. By skillful management of
microorganisms, and careful control of the temperature,
we can make fermentation starter a pure culture of yeast.
Therefore, fermentation starter is an important process inmaking delicious sake.

A fermentation starter

04

Rice
washingand soaking

Ricesteaming

Koji making

Fermentation

Moromi (Fermentation mash)

Now, the main elements for making sake are ready.
Let's make moromi , the fermentation mash, by putting thesteamed rice, koji , water, and fermentation starter into afermentation tank.
The fermentation mash is prepared through three steps.
Each of these materials (except the fermentation starter)
is divided into three portions with increasing volume,
and a portion of each material is added in sequence. Thismethod is effective to avoid lowering the yeast density
and the acid level in the mash and to prevent bacterial
contamination.

Steamed
rice

Water

Rice
koji

Fermentation
starter(1st day only)

Final addition

4th day

Pressing

Sake

The Storyof SakePressing the mash,
pasteurization, bottling

After the fermentation, the fermentation mash contains
sake and a lot of solid substances, such as undissolved
rice and koji . It is mushy at this point. To obtain sake,the mash is pressed with an automatic filter press or a
traditional press called fune (because it looks like a fune
meaning a boat in Japanese).The solid material that is
separated out is called sake kasu (sake cake). After thispressing process, we have new sake with a pleasantaroma.

Automatic filter press for sake

Middle addition

3rd dayFirst addition

1st day(the three-step
preparation of
fermentation mash)

On the first day, the entire quantity of fermentation
starter, 1/6 of the total volume of steamed rice, koji , andwater are used (the first addition). On the second day, no
addition. Little by little yeast will grow. It is called theodori stage. On the third day, 1/3 of the steamed rice,koji , and water are added (the middle addition). On the
fourth day, 1/2 of the steamed rice, koji , and water are
added (the final addition). After proceeding through thethree steps, the fermentation mash is mixed (a process
called kaiire ) every day. The fermentation tank should
be kept at a low temperature (about 15˚C). After three
weeks of fermentation, the alcohol concentration of thefermentation mash will reach 18% and level off.

Fune , a traditional press for sakeThefermentation
tank, soon after
the final
addition.

The mash is poured into bags, and the bags
are laid in a traditional press

After aweek, thefermentation
mash is covered
with lots of
bubbles.

Generally, new sake is pasteurized in a process calledhiire (heat sterilization). The purpose of heat sterilization
is to kill bacteria that deteriorate sake during storage
and to prevent further enzymatic reaction. After heatsterilization, sake is stored for a certain period. Then it isbottled and shipped.
05

will be a sake connoisseur
Product information Youafter
reading these pages.
Rika, a housewife, comes into a liquor shop to buy somesake.
* Enjoy Sake
* Drinkmoderately

Owner: Hello! May I help you?
Rika: I’d like a bottle of sake.
Owner: We have many types of sake. Which one would you
like?
Rika: To tell the truth, I don’t know which one I shouldbuy. Please tell me about sake.
Owner: OK. I’d be happy to. First of all, let me explain
the various types of sake to you. According to thematerials used and the rice-polishing rate, sakeis roughly classified into 4 categories: Ginjo-shu ,junmai-shu , honjozo-shu , and ordinary sake. The
raw materials for making sake, beside rice, include
alcohol, saccharides, and acidulant. Junmai-shu
is sake made from only rice, without addition of
alcohol or other ingredients.
Rika: You mean junmai-shu is made from 100% rice?
How does junmai-shu taste?
Owner: Junmai-shu is full of the taste that comes from rice,
and it tastes rich. See the label? It shows that is
made from rice and koji .
Rika: It sounds delicious.
Owner: H o n j o z o - s h u i s m a d efrom rice, koji , and a little
bit of brewers alcohol.
To make junmai-shu , themash is pressed after thefermentation. On the other
hand, to make honjozoshu , a little brewers alcohol
is added before pressing.
Rika: Why do they add brewers
alcohol?
Owner: In the Edo period (16031868), sake breweries
found that adding shochu (Japanese liquor) made bydistilling sake cakes to the sake improves its flavor.
It was an important technique(Hasira-shochu )during that period. We have inherited this method
and utilized it to make honjozo-shu . Now, distilled
pure alcohol (brewers alcohol) is used instead ofshochu .
06

Rika: What is that brewers alcohol made from?
Owner: It’s not like the alcohol made by chemical means
used for sterilization. Brewers alcohol for sakemaking is made by fermentation of raw materials
such as sugar cane (molasses) using yeast. So it iscalled jozo (fermented)-alcohol in Japanese.
Rika: How much brewers alcohol is added?
Owner: To make honjozo-shu , the equivalent of up to 10%of the weight of the rice used for sake making canbe added. From 1,000 kg of rice, approximately
2,400 liters of junmai-shu or approximately 3,000liters of honjozo-shu are made.
Hasi

ra-sh

Rika:

ochu

How will the flavor of the sake change after brewers
alcohol is added?
Owner: Sake will be less acidic, and its taste will become
light and dry.
Rika: What does honjozo-shu taste like?
Owner: It has a good balanceof tastes and flavors
derived from rice. We
recommend honjozo- Dry Sour Sweet Umami Bitter Salty
shu for everyone,from beginners to
Taste of sakesake connoisseurs.
The label shows that
it is made from rice,koji , a n d b r e w e r s
alcohol.
Rika: It will be tasty and easy to drink.
Owner: The largest amount of sake produced is ordinary
sake. Simply put, this is sake that is pressed out
after a bit more alcohol is added than that is used for
honjozo-shu . The label shows that it is made of rice,koji , and alcohol. For ordinary sake, it is allowed
to use saccharides and acidulant. Saccharides andacidulant will appear on the label when they areused.
Rika: What does ordinary sake taste like?
Owner: It tastes a little sweet, light and smooth. Someordinary sakes are packed in cartons.
Rika: So it sounds like it’s for casual drinking.

Dry

Sweet

Owner: Ginjo-shu is made by a special method using highly
genshu .
polished rice. Since ginjo-shu needs a lot of care Rika: How can I tell if a sake is sweet or dry?
and production cost, only a little is produced. A
Nihonshu-do (sake meter value)
little of alcohol is added during the process of someginjo-shu . Alcohol is effective to adjust the taste. It
Sugar
LittleA lot
also has the effect of extracting the fruity aroma that
content
tends to be absorbed by yeast and rice grains into
the sake.
Rika: What does ginjo-shu taste like?
Owner: It has the fruity aroma of apples, melons, or Owner: Sweet or dry on the label is a useful indication.
bananas, and a mild taste. During the production ofSome sake shows its nihonshu-do (sake meter value)
ginjo-shu , the chief sake maker concentrate so hardon the back label. Sake meter value is a kind of uniton making ginjo-shu . Ginjo-shu is often exhibited atof density, and generally it expresses the amount ofsake competitions all over Japan.
sugar contained in sake. Sake on the market ranges
in sake meter value from +10 to -10. The higher the
Delicio
number, the lower the sugar content. If you like aus!
sweet sake, choose one with a minus value. If you
want a dry sake, select one with a plus sake metervalue. However, the acidity of sake influences its
taste. So, please use the sake meter value only as arough reference.
吟醸
Rika: Do you have any special sake?
Rika: I would like to taste it!
Owner: Ginjo-shu is expensive, but it is worth the price.
Kijo-shuRika: How is sake treated after the pressing?
Owner: The flavor of sake is easily changed by enzyme
reaction. So, sake is heated to approximately 65˚C
to stop the enzymatic reaction. This process has
the effect of heat sterilization, too. After it is heat
Sake
treated, the sake is generally stored over the summer
for aging, and shipping starts in the beginning ofautumn. The stored sake contains approximately
20% alcohol. Before bottling, it will be diluted Owner: Yes, there is a sake called kijo-shu . Normal sake iswith water to reduce the alcohol concentration
made using 130 L of water for 100 kg of rice. Kijoto approximately 15%. Sake will be sterilized by
shu is made using 70 L of water and 60 L of sakeheating again just before bottling.
for 100 kg of rice. You can call it sake made with
Rika: Is there any sake that is not heated?
sake. It has a rich taste with balanced sweetness andOwner: Yes, there is. A sake that is not heated at all is called
acidity. After aging, its color will change to amber.
nama-zake (nama means raw). Nama-zake retains its
Besides that, there is long aged sake and cloudy
just-pressed freshsake as a variation of sake. Recently, sparkling sakeflavor if it is stored Fr
is produced. It is good for toasts and popular amongesh!
in a refrigerator.
women and the younger generation.
RefrigeratorSake that is stored
Rika: Wow, I’ve learned so much about sake.
without heat
Owner: OK, now you can choose the sake that you reallytreatment, andwant.
then heated justbefore bottling iscalled namachozoshu . Nama-zakea n d namachozoshu are indicated on their labels. Sakes without
indication of nama-zake or namachozo-shu on theirlabels have been heat treated two times, once before
storing and once before bottling.
Rika: Why is alcohol in sake diluted before bottling?
Owner: An alcohol content of 20% is generally too strong.
Some sake is not diluted. In this case, it is labeled as
生 生

生

生

生

生

生

07

How to evaluate and enjoy sake
The opinions of specialists may be useful, but the mostimportant thing is to find sake that you like. In other words,
just as everyone has his/her own favorite foods, taste forsake depends on the person. How do we evaluate sake andhow is it served?
(1) How to evaluate sake
Like other alcoholic beverages, sake is evaluated on thebasis of color, taste, and aroma. A ceramic cup with two
blue concentric circles on the bottom, called kikichoko isused for sake tasting by professionals.
Color:
The color and transparency
are evaluated. Sake with dark
yellow or brown color has
probably been stored for along time. Blue circles on akikichoko (tasting cup) areuseful to see the color andtransparency of sakes.
Kikichoko (tasting cup)

Aroma:
There are many kinds of aroma in sake, including a fruity
aroma called ginjo -aroma, the rich aroma of aged sake. They
are evaluated on the basis of strength and balance.
Taste:
Taste is evaluated on the scales of: sweet/dry, rich/light,
and with/without umami. If a sake contains a lot of sugar,
it tastes sweet. If there is less sugar in it, it tastes dry. On
the other hand, the acidity of sake offsets the sweetnessof the sugar. Even if the sugar level is the same, the more
acidic sake will taste dryer, and the less acidic one will
taste sweeter. Concerning richness and lightness, a sakecontaining a lot of alcohol, sugar, acid, or amino acids will
taste rich, and a sake with less of these components will
taste light. A sake with a high level of amino acids may
suffer unpleasant heavy taste after it has aged.

Components
in sake and
taste

Acids

Sugar

The Storyof Sake(2) Temperatures for serving sake
You can enjoy sake at various temperatures andwith various dishes.Unlike beer and wine, sake canbe enjoyed at a wide range of temperatures. The
appropriate temperature for serving depends on type ofsake.
Ginjo-shu has the aroma
of apples or bananas, so it
is suitable to drink cool.
Sake with a fruity aroma
is good for the first half ofdinner. Most junmai-shu
have a rich taste, so they
are suitable for serving
with rich-tasting dishes cooked with soy sauce, sugar
and oils. They can be served at various temperatures,from cold to hot. Strong matured flavor and acidity will
be softened by warming, which makes it even moredelicious. Honjozo-shu is a versatile sake that can beenjoyed from cold to hot. Honjozo-shu will go well withany dishes.
(3) Combinations of sake and dishes
Each region of Japan has its own unique local dishes.
People feel that a local dish goes well with sake madein the same region. Please try local sakes in various
regions.
(4) Drinking cups
The taste and aroma of sake differ depending on
drinking cup.
There are many sake cups made of different materials(ceramic or glass) and shape (widely opened or narrow
and tall). Recently, an increasing number of restaurants
are serving sake in wine glasses. With different types ofsake cups, how does sake taste? Let’s try and enjoy!

Amino
acids

Light

Clear
Heavy

Alcohol

Strong Weak

Sweet

Dry

Choko (sake cups)

Tokkuri and choko

National Research
Website:Institute of Brewing https://www.
nrib.go.jp/
3-7-1, Kagamiyama, Higashihiroshima,
English/Hiroshima, 739-0046

Rich

TEL：+81-82-420-0800 FAX : +81-82-420-0802
e-mail：eng_info@nrib.go.jp

08

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August 2022