Making Miso: Intro
“The key to the art of making fine
miso lies in the process of fermentation,
a process which, throughout its long and
varied history around the world, has served
three fundamental purposes: the improvement
of a food’s digestibility; the transformation of its
flavor and aroma, color and texture; and its preservation
without refrigeration. Watching the drama enlarged a
thousand-fold and presented in time-lapse color photography,
one witnesses a near-miraculous world in which tiny spores burst into
blossom like elegant and complex flowers, enzymes reach out inquisitively
like long fingers melting solid particles at their touch, and populations of mold
explode until they have totally enveloped the foods – or “substrates” – which support their life.” – The Book of Miso ( page 28.)
What is Miso? Read full text
Watch a video about South River Miso
The Basic Ingredients
South River Miso is made in three phases of a double fermentation process. First, over a three-day period, a culture is grown on steamed grain, usually rice or barley. This cultured, fermented grain, called koji in Japanese, is mixed with sea salt.
In the second phase, this salted koji is then mixed together with cooked beans, usually soybeans, which are mashed under foot and inoculated with a small amount of already mature miso.
In phase three, this mixture –raw miso– is placed into large wooden vats, where it will undergo a lengthy fermentation, lasting anywhere from three weeks to three years, depending on the variety of miso and its salt content.
(Ingredients for Barley Miso are shown here.)
What is Miso? Read full text
The Production Room at South River
The cooking cauldron, to the left, is set into a massive, wood-fired masonry stove. The washing and soaking kettles are to the right.
Phase One: Making Koji
Cooking with wood fire
First step: steaming the grain. Photo shows masonry stove with cooking cauldron to left and wood fire box to right.
Removing steamed grain from cauldron
The grain is removed from the cauldron after steaming for about one hour, until the starch is completely cooked. The grain is placed onto cooling tables.
Grain cooling after steaming
The grain is formed into “mountains” to increase surface area, so that it will cool down faster. (Rice is shown here.)
Inoculating the steamed grain
After the grain cools down to about 112°F, it is inoculated with the spores of the mold, Aspergillus oryzae. (Rice is shown here.)
This is very much like an agricultural process, for example, like sowing oats onto the prepared field of earth.
In this case, the entire process is “raised up”. Instead of sowing grain on the earth, we are sowing spores of a specific
mold on a “field” of steamed grain.
Rubbing the grain
After the grain is inoculated, it is mixed by hand to insure that each grain comes into contact with the spore. (Rice is shown here.)
Right photo:The inoculated koji is transfered into the crib.
Left photo: The crib, filled with koji, rests before the masonry stove.
After the grain is sufficiently mixed, it is placed into a large wooden crib at about 82°F. It is now called koji.
The koji will stay in the crib overnight. As the mold begins to metabolize on the grain, it generates heat.
By the following morning the temperature of the koji will be about 100°F.
It is meaningful that the large wooden incubation box is called a ‘crib’.
This is the start of the miso making process. The inoculated grain is like a newborn baby and is gently put to sleep in the wooden crib.
The Koji Room
Left photo: The koji room door from the production room.
Right photo: Looking into the koji room.
The koji room is a small incubation room with a low access door. This room is pre-heated to about 90°F until several hours later when the warmth given off by the koji itself maintains the room temperature.
First we stir the koji in the crib and then distribute it into small wooden (cedar) trays, which are stacked in tight formation as shown in the next photo.
Trays stacked in koji room
A few hours later the koji will be stirred again in the trays. The koji trays will be re-stacked into a more open formation to dissipate heat.
Koji trays in open formation
This photo shows a white bloom of mold growth over the grain. It is now about 48 hours after the grain was originally steamed
and inoculated. At this stage, when the koji is in full, fragrant, white bloom, it is ready to harvest. (Barley is shown here.)
function of the koji is to produce an abundance of natural enzymes that later, in the second stage of miso fermentation, will break down
proteins, starches, and fats into more readily digestible amino acids, simple sugars, and fatty acids.
Before and After
The tray on the left shows koji about 20 hours after inoculation and that has just been put into the tray for further incubation in the
The tray on the right shows koji ready to harvest.
Koji ready to harvest
The mycelia of the mold have bound the grain together into matted clumps. (Barley is shown here.)
We scrape the koji out of the cedar trays and push it through a stainless steel screen to break up
the clumps into individual grains. The koji is then mixed with a measured amount of sea salt and put aside.
– The Book of Miso ( page 204)
Making koji in 17th Century Japan
This ancient drawing shows workmen making koji in a relatively large 17th century work place. At the lower left,
they are feeding the fire to cook rice in the large steamer above. A cloud of steam hovers over the whole workplace.
“The steamed rice is being carried in buckets to straw mats, where it is spread and cooled. After inoculation, the rice
is rolled up in the mats and carried to the incubation room (upper center). The finished koji is carried out and mixed
with salt in a large tub (lower right). Men bind staves with bamboo hoops to make wooden buckets in which they will
sell the finished miso (upper right). The water carrier heads for the shop’s well. In the storeroom, bales of rice in straw
sacks and stacks of koji trays await use (upper center).” –
The Book of Miso ( page 196)
Phase Two: Preparing the Beans
The beans are first sorted by hand. Decadent beans, stones, and other debris are removed.
(Soybeans are pictured here.)
Theoretically, any bean can be used in making miso.
At South River we use soybeans, chick peas, and azuki beans to make different varieties of miso.
The traditional bean used in Japan is the soybean, with which miso is most commonly identified.
The beans are first washed and then soaked overnight before cooking. (Soybeans are pictured here.)
Long, slow, gentle cooking is key to the bean cooking process. The swelled beans are gently boiled
by wood fire for about 20 hours. For the first six or seven hours, we feed the wood fire for active cooking.
Then the beans continue to cook overnight by the warmth of the masonry stove. (Soybeans are pictured here.)
Removing Beans from the Cauldron
Left photo: Removing beans from the cauldron
Cooling the beans in the stainless steel mixing box.
Cooked beans cooling in the mixing box
Preparations for mixing
Left photo: Salted koji (lower right of photo) is brought to mixing box.
Right photo: The beans are inoculated with “seed miso”, a small amount
of already mature miso of the same variety. This is equivalent to a sour dough starter in bread making.
The seed miso inoculates the new batch with microorganisms cultured through the great lineage of miso
making, not only at South River, but stretching back into ancient times. The seed miso consists of a slurry
made from the bean cooking liquid and some mature miso.
The Wedding Ceremony
This is the heart of the traditional miso making process. Right up until World War II, and before the
advent of modern food processing, all miso was made in this way, by treading the beans and mixing in
the salted koji underfoot.
Christian Elwell writes: “I call this the wedding ceremony. I feel like a
priest when I am treading the beans. The beans, the salted koji are married together, becoming one…
something new Nature herself does not bring together except through the human being. The human hand,
the human foot –from these, divine healing forces stream into the new life bearing substance we call miso.”
(Photo from 1983)
Special plastic leggings and organic cotton socks are worn
for the treading process.
Making miso the traditional way
Right photo: A peaceful treading.
Left photo: Salted koji being
mixed in with the already crushed beans.
The treading process is done in a very orderly way. It takes
about one hour to mix 500 pounds of miso. Special plastic leggings and organic cotton socks are worn.
This labor intensive process results in miso with a whole grain, chunky texture, which is the hallmark
of traditional miso. The chunky texture allows for greater movement and exchange of fluids in the fermentation
vats to follow. It also results in miso with a more alive taste and complex flavor, due to the fact that there are
some whole beans and whole grains which ferment in a different way, and at a different rate than the crushed
beans and grains.
Our customers often remark that there is something about South River Miso that sets
it apart from all the rest. We believe that food made from the heart, by the human hand and foot, has a different
quality than food made by mechanical machinery. The human being becomes a central ingredient in the food making process.
Raw miso ready for fermentation
Left photo: The treading and mixing process is completed.
Right photo: The raw miso is removed from the mixing box.
Phase three: Final Fermentation
Closing the fermentation vat.
The raw miso is taken to its designated fermentation vat. Once the vat is filled, the miso
is smoothed off and covered with a muslin cloth. A wooden pressing lid is placed on top of the muslin cloth. Then stone or concrete
block weights are piled on top of wooden beams above the pressing lid. This brings liquid up to the surface and seals off the miso from
outside contamination. (Right photo from The Book of Miso , front piece.)
The miso may age in its designated fermentation vat anywhere from three weeks to three years, depending on variety and salt content.
The fermentation vat building
This large, timber framed building has radiant floor heating fed by a wood furnace to control temperatures during the winter months.
The fermentation vat building
“When after one to three summers, the miso has come to maturity, it contains an immense number of vital and very beneficial microorganisms and enzymes. These are present in the natural miso you serve, ready to continue their work of aiding digestion within the human body.” – The Book of Miso ( page 29)
After fermentation is complete, the miso is harvested from the vat and taken to the packing room where all of our miso is packed by hand.
South River Miso
The finished product, packaged and ready for distribution.