Outside of Tours in the very typical French campagne, there’s an old chateau that hides a surprise. Actually, the surprise is hiding behind the chateau, in its old stables. Surrounding a courtyard and half-abandoned, the stables haven’t housed cows in quite some time. But something is living there. And its name is Aspergillus oryzae! Yes, the “national fungus” of Japan, otherwise known as koji. And the koji is hard at work, transforming soybeans into traditional Japanese miso.

Takayoshi in his garden, green even in December

Takayoshi in his garden, green even in December

Well the stables also house a family, a family from Japan. Takayoshi and Akiko Hirai and their two small sons have renovated the decrepit French building themselves, turning it into a beautiful home in simple, airy Japanese style. Their home is surrounded with bountiful gardens containing apricot and apple trees, honeybees and vegetables, many of which Takayoshi uses in his production of traditional Japanese products for his enterprise Sanga.

During my sojourn in Angers I was studying traditional French foods. But this usually happened in the classroom, or on a tour of a production facility. I didn’t often have the chance to get my hands dirty, to work on a farm or to make cheese, but this is what I love best, and by December I was missing it. So when I went with a Japanese friend to learn how to make miso from the Hirais, I plunged my hands into the soybeans and mashed them with the utmost enthusiasm.

On a cold December morning, Takayoshi picked us up from the end of the tramline in Tours and drove us about 20 minutes to his home. After having tea with the family and a Franco-Japanese couple that had traveled in from Paris, we donned bandanas and moved to a production facility in the corner of the house.

Freshly boiled soybeans were cooling down as Takayoshi explained the production process. We’d be mixing the soybeans with a bunch of salt and two types of koji: white koji (made from rice) and brown koji (made from barley). Koji is made by inoculating the cooked grains with Aspergillus oryzae cultures. When the koji is mixed with other ingredients, in our case the soybeans and salt, the cultures break down carbohydrates into amino acids, fatty acids and simple sugars that add incomparable flavor and depth to the final product.

One of these amino acids is glutamate, responsible for the savory taste known as umami. Umami is the name for the rounded and deep taste that is also found in meat, mushrooms and aged cheeses like parmesan (side note: I learned that Japanese people don’t really use ‘umami’ in that specific way; it translates simply as ‘delicious taste’). The miso fermentation process is also known to create beneficial compounds such as cancer-preventing isoflavones.

Clockwise from top left: soybeans cooling; rice and barley kojis; mixing ingredients.

Clockwise from top left: soybeans cooling; rice and barley kojis; mixing ingredients.

After mixing the salt, soybeans and koji by hand to ensure that there are no more lumps, we pressed the mixture it firmly into plastic buckets, avoiding any air holes lest the mold proliferate too much inside (the addition of salt into the soybeans helps to control this mold and enable a slow, steady fermentation). After covering the surface with an extra layer of salt, it was time to wait—at least one year—until the miso would finally be ready.

According to Takayoshi, industrial miso producers in Japan use tricks like ‘aging’ the miso at a very high temperature to speed up the fermentation process. But slow fermentation results in richer, more complex flavors. Traditionally, miso was produced during winter when fewer airborne microorganisms were present and when temperatures were cool, allowing for a slow start to fermentation.

I realized that making miso is a lot like making cheese; we start with a few simple ingredients, but by altering any step in the process, either in production or maturation, we can create infinitely different results.

Clockwise, from top left: mixing ingredients; finishing with salt; Sophia and Wakako with our finished bucket; an aged red miso.

Clockwise, from top left: mixing ingredients; finishing with salt; Sophia and Wakako with our finished bucket; an aged red miso.

Misos are shaped first by their ingredients; the more koji, the sweeter the miso.  Differences between misos are also played out between regions of Japan, with barley-based varieties produced on the island of Kyushu, and dark, 3-year-aged varieties from Nagoya, for example. And it’s not just regional tradition that affects the final product; in contrast to industrially produced miso, homemade misos vary from one home to another, each mirroring its household’s specific microbial environment.  Like in cheese affinage, the final product is dependent on a balanced ecosystem of microorganisms that has been able to flourish; longer-aged miso will have a notable presence of Lactobacilli, friendly bacteria that protect against pathogens in the food.

And the subtle differences can be tasted, as I realized when sampling a range of Takayoshi’s homemade white and red varieties, some aged up to 3 years. The older the miso, the deeper and more complex the taste. It reminds me of comparing a real Aceto Balsamico di Modena that’s been aged for over 12 years with a 1-year-old balsamic vinegar, or comparing a 36-month Parmigiano Reggiano with a younger parmesan. I’ve never been a patient person, but I’m learning that in the world of fermented foods, great things can only be created slowly.

And so the white bucket was closed and I left the Aspergillus to do the rest of the work. And as the sun went down we shared coffee and the heart-shaped biscuits that Akiko had just made with her sons. The biscuits, buttery and fresh out of the oven, reminded me that being impatient is silly; until my miso is ready, I have plenty of other delicious foods to keep me busy.

Eating cookies; outside the Hirais' converted stable house.

Eating cookies; outside the Hirais’ converted stable house.