Want to know how Miso is made? Join us on a tour at Hikari Miso’s Iijima Green Factory located in the picturesque Nagano countryside of Japan.
In Japan, many food companies offer tours of their factory. Throughout our travels in Japan, we’ve visited a fishcake factory, Kikkoman’s soy sauce factory, breweries, and shingen mochi factory. We enjoy visiting food factories with our children so they can learn and appreciate the various processes that go into creating the food we eat. When our long time partner Hikari Miso offered us a tour of their miso factory, we jumped on the opportunity to learn more about miso making.
Hikari Miso Iijima Green Factory
Hikari Miso’s Iijima Green Factory is located in the valley of Central Alps in Nagano Prefecture, about a 3 hrs drive from Tokyo. The surrounding of the factory is absolutely beautiful, with views of mountains, green scenery, and rice fields.
The factory is not open for public tours to visitors so we were excited to have this unique behind the scene opportunity to see how our favorite miso is made.
How Miso Is Made
Before we start the tour, let’s quickly go over how is miso made.
Miso is made with just a few ingredients, koji, soybean, salt, and water. Cooked soybean is mixed with rice koji, water, and salt, and then it’s simply fermented and aged. At Hikari Miso’s factory, miso is pretty much processed the same way but on an extremely large scale. They also use different rice, soybeans, and salt to create various flavors and varieties of miso.
Why Does Miso Taste So Good
Made of just a few ingredients, why does miso taste so good and packed with umami flavors? The secret lies in the fermentation process where the soy protein is broken into peptides, and further into amino acids. The amino acid is where the sweet flavors and umami comes from.
Ready for the tour? Let’s go!
The Ingredients for Miso
After arriving at the factory and meeting the production team leaders, our family was taken on a guided tour of the facilities. To enter the miso-making building, we had to scrub our hands for a specified amount of time and put on a clean suit and hair net so we don’t contaminate any of the food being produced.
The location of the factory is one of the reasons why Hikari Miso tastes so good. Being at the foot of the Central Alps, there is abundant high-quality groundwater from the snowmelt. The water is used to cook soybean, rice, and truly one of the main ingredients in miso.
In 2009, Hikari Miso also started to repurpose the wastewater from miso production. They are able to capture methane gas from the wastewater to generate power.
The miso factory tour focused on the main ingredients of miso, starting with soybeans. We learned how soybeans are stored, such as organic soybeans have to be stored completely in a separate silo by themselves so no cross-contamination happens. We also learned how they’re sorted, peeled, cleaned, and soaked prior to steaming.
Rice and Salt
The next ingredients we learned about are rice and salt. Everything is on a massive scale. The rice goes through a selection process, then soaking, steaming, and cooling. The cooling step is required before introducing koji-kin. After adding koji-kin to rice, it becomes koji.
Miso Making Process
After the tour of how ingredients are selected and prepped, we stepped into the hot and humid miso-making building. Since the soybean and rice need to be cooked, it was a very hot environment with steam coming out from various vents.
The first stop inside the building is a view of the giant koji cultivating machine. It is one of the largest in Japan (34 tons) and when the door opened to show us the interior , we were blasted by a super-hot air. What an incredible welcome!
The entire miso making process is automated, from cooking the ingredients to mixing the right amount of ingredients for different types of miso.
Heading up to the second floor of the building, we could see soybean being cooked.
After cooking, soybeans are ground up and extruded.
From the other side, cooked rice and koji mixture are piped in to mix with soybean.
The mixture is then placed into stainless steel storage tanks to ferment.
The Storage Facility
One of the largest buildings on the factory ground is the storage facility. Inside the storage facility, there were endless towers and rows of miso fermenting and aging in stainless steel tanks.
These storage tanks are ginormous. Here is one on a forklift to provide perspective.
Packing and Production
In the last part of the tour, we saw how miso is transferred from the storage tanks and packed into consumer packages.
There were production lines for all different types of miso, as well as miso soup and other shelf-stable miso products.
The majority of the packing processes are fully automated.
We’re thankful the Hikari Miso team for the wonderful miso factory tour. The team generously spent time with our family and answering all the questions we had about miso making. It was eye-opening for us to see miso being made on such a large scale.
To learn more about miso, check out this post: