Tour of Koji-ya Saburouemon Miso factory

Toyko

This tour was organized by my dear friend Midori Uehara and Nakaji Minami who runs Koji School, and joined by koji students Miyuki and Minami. (Pictured at the end of post at a beautiful lunch.)

Yesterday

A few days ago

Over a week

Almost two weeks ago we visited Umai Miso, a 200-old-miso factory in Toyko, one of only eight left in this metropolitan area of 38 million people.

We stood in the main space surrounded by the layers of items in use, or once used, by the 7 generations that have made miso in the building.  There were faded children’s drawings pinned on large kioke (木桶) (open cedar barrels), and there was equipment from various eras. Boxes and bins were piled high on a couple of 2-ton kioke that hid behind somewhat smaller ones. Most of the miso that was fermenting was in various smaller sized brightly colored plastic kioke. The miso maker, Mr. Tsujita, explained that the large kioke are empty, as they are just too big now. Instead, they need to make more variety—eight—in smaller amounts. This business has had to adapt to changing a changing food culture and climate.

There is one miso they make that is a nod to the original miso but Mr. Tsujita said tastes have changed. He said this change started after WW2 when the government pushed schools to serve bread instead of rice. This began the generations of children who grew up eating white bread. He shared that his customers want lighter, less salty, easier-to-use miso and so he has pivoted based on demand. He is the only maker that makes lighter-style miso, most specifically the short-fermented Kyoto-style white miso. He feels that it is important that the white miso is made with the highest quality ingredients because it will come through and it is easier to hide lesser-quality ingredients in a dark miso. Most people now prefer light miso because it is sweeter and easier to use.

His white miso, which he calls the Kyoto style, is an ancient, historical style with a strong structure and discipline associated with it. It’s a 1:1 ratio of soybeans to white rice koji with a 4.5% ratio of salt by weight. This miso is aged a mere week. The enzymes from the koji have begun to break down the starches and proteins offering the light umami flavors of fermentation but in one week the microbes that ferment haven’t had a chance to consume all the sweetness brought out in the rice by koji. It is deliciously light, sweet, and creamy.

The other white miso that Koji-ya Saburouemon makes has the same 1:1 ratio, salt is 9.2%, and it is aged for six months. Mr. Tsujita feels the koji is at its sweetest at the six-month mark. I found two interesting aspects to this miso. The first is that it has a delicious sweetness and in a trick of the tongue, or fermentation, it tastes less salty than its 4.5% counterpart. The other noteworthy part of this miso is in the process. It stays creamy white because the soybeans are cooked first, then the cooking water is drained (those of you who have cooked soy know the cooking water becomes a caramel color), and the beans are steamed briefly before being mixed with the koji.

Edo miso is the dark type of miso that is of the Tokyo area. Mr. Tsujita said that this style is fairly recent in miso history and came about because the makers of Tokyo wanted to distinguish their kind of miso. His own “house miso” which is the original miso of the house is called Mother’s Proud – because when people eat it – it reminds them of their mother. This miso Is 1:1 koji and soy. It is 10.6% salt and is best between 10 and 13 months. It had an earthy, to my palate clean classic flavor. It was well-balanced and super tasty. He makes a second version of this miso with a rough chop on the soybeans. It is always a surprise how different the size of the chop can have on a ferment. Same ingredients, same ratio, and yet the flavor is completely different. It shouldn’t be a surprise though when you think about texture being more than just mouth feel. It is based on the surface area exposed to the work of the microbes. Bigger chunks = less surface area easily accessible to the microbes’ magic.

Upon arriving the first thing Mr. Tsujita showed us was the rice steaming barrel. He explained that the grain of the wood staves was cut a little bit differently than for the kioke fermenting barrels. The straight grain on the steamer offers more airflow which is better for controlling the moisture of the steaming rice.

This barrel is beautiful in its simplicity of use and I think you’ll agree it is beautiful to look at as well. Steam is forced through a hole in the solid bottom of the barrel. The rice then sits on a false bottom that is porous and made of bamboo staves. Over the steam hole, there is an octagon block that disperses the steam under the bamboo and up through the rice. Nowadays the steam is piped in from a kettle but in the past the water and fire to heat it were underneath the barrel.  Mr. Tsujita said the barrel had a natural fail safe – if the fire got to hot the bamboo straps would burn the barrel would split apart dosing the fire as it did.

He explained that for koji making the rice is steamed to the opposite of al dente—instead of soft on the outside and harder in the middle his rice is soft in the middle and gets a crust on the outside when cooled to inoculate.  

Next stop the koji cave.

Our group rounded the corner and a team of employees were giving the 50-year-old kojibuta 麹蓋 (cedar koji tray) a spa treatment—maintenance they get once every five years. As you can see by the photos, these trays are small. They have tried different trays but found this size works the best for them.

The koji room was also built 50 years ago. The space is made of Ōya-ishi (大谷石) Ōya stone, an igneous rock created from lava and ash. The outside walls are textured to create more surface area to allow for airflow while the inside surface of the stone bricks are smooth to lessen the surface area exposed thereby holding in the heat. Mr. Tsujita explained the importance of the small door in keeping the humidity and temperature of the room very stable. He said that it was more important than the ease for the worker who must stoop in and out of the door, then he laughed saying his knees would appreciate a bigger door.  We crouched down and folded our bodies through the opening. The space opened into a thick koji-scented air--floral, sweet, and mushroomy. In the space, we saw the trays stacked along the wall. Each tray was covered with a rice straw mat. We learned the mat must be made anew once a year.

The rice straw can be difficult to source as most farmers now harvest the rice with a tractor that chops the straw and for these mats, they need long straight lengths of straw. For the time being, they are working with a farmer whose harvest implement preserves the straw stems.

Managing the fermentation and doneness of their products is harder to predict with the changes in the climate. In recent years the rice is harvested before it is fully developed giving it a higher moisture content. This affects the koji quality. Less predictable is the weather. They have always relied on the temperature of the seasons. The timing of aged miso-making is traditionally based on a fall start. The last of the warm weather would get the fermentation started and the cool winter months to slow it down for a deep flavor development. Now, winter is no guarantee of enough consistent cool weather. Mr. Tsujita said it is a huge dilemma for him. To take care of the miso fermentation he now must run air-conditioning which he acknowledges exasperates climate change. This is hard for him.

We didn’t have a chance to talk to his son, 30, the eighth-generation miso maker who was working while his father generously shared knowledge and hours of his time with us. If we had I would have asked him how he sees himself navigating the future of small traditional miso making in Tokyo.

どうも ありがとう ございます。