Next-Generation Sake Brewing with IoT: ESP32 and Sensors Supporting the Evolution of Tradition

Sake brewing is a traditional industry that has been supported by the experience and intuition of toji (master brewers) for many years.

At our brewery, we are incorporating IoT (Internet of Things) into this delicate process.

Even at our brewery, we are working to "visualize" the state of sake brewing numerically by combining the "ESP32" microcontroller with various sensors.

This article will introduce how next-generation sake brewing utilizing IoT leads to stable and improved quality.

Challenges Faced by Traditional Sake Brewing

In sake brewing, both koji production and fermentation (of moromi) are greatly affected by slight changes in temperature and humidity.

Until now, brewers would patrol the brewery multiple times a day, judging conditions based on their touch and experience.

While this method is highly valued as a skilled technique, it also presented several challenges.

These included the burden of patrols late at night or early in the morning, and the reliance of judgments on the individual senses of each artisan.

To address these challenges, our brewery focused on IoT sensing.

"Visualizing" the Sake Brewery with ESP32 and Sensors

Our brewery centers around the ESP32 microcontroller, which allows for low-power Wi-Fi communication.

We have built a system that connects multiple sensors to the ESP32 to measure the environmental conditions of each stage of sake brewing in real-time.

What is ESP32?

It might be easier to understand if you think of it as a computer for electronic crafts, like Arduino, similar to Raspberry Pi which is a simple educational computer.

It has a built-in CPU, memory, and hard disk, and some types even come with Wi-Fi. It only has functions for embedding into machinery, and lacks the capacity and power to run operating systems like Windows or Linux, directly using a language like C++.

Cheaper ones start from around 1,000 yen, and even with various sensors attached, the total cost can be kept to a few thousand yen.

Signals from sensors are connected to the many pins on the back of the board, and the received data is sent via Wi-Fi to Google Drive Spreadsheet for data management.

Of course, if you connect switches based on sensor signals, you can turn things ON/OFF. So, in our koji-making room, we have a system that automatically turns the heater ON/OFF based on the product temperature.

Data management during fermentation is handled similarly, but for product temperature and specific gravity, we use a sensor called TILT and manage it with Spreadsheet.

Constant monitoring allows us to detect even slight changes and reduces the risk of introducing unwanted bacteria by opening tanks.

Sensing to Support Koji Production

Koji is one of the most delicate processes that determines the quality of sake. In the koji room, the following four values are continuously measured by sensors connected to ESP32:

• Product temperature — The temperature of the koji itself
• Room temperature — The overall temperature of the koji room
• Humidity — The moisture content of the air directly linked to koji mold proliferation
• CO2 concentration — An indicator of koji mold activity

By understanding these simultaneously, we can numerically grasp how actively the koji mold is working at any given moment.

Sensing for Fermentation (Moromi) Management

In the fermentation process that occurs in the brewing tanks, room temperature, humidity, and CO2 concentration are also measured using ESP32.

Since CO2 is generated with alcohol fermentation by yeast, tracking its changes allows us to accurately grasp what stage the fermentation is in.

Automatic Measurement of Specific Gravity and Product Temperature with TILT

Particularly important for fermentation management is the specific gravity of the moromi.

Specific gravity indicates the degree to which sugar is converting to alcohol and is a key factor in understanding the progress of fermentation.

Our brewery utilizes TILT, a floating measurement device for tanks.

TILT automatically measures specific gravity and product temperature within the moromi and captures this data via ESP32.

This allows us to continuously monitor the fermentation state without having to take samples from the tank.

This is apparently commonly used by American beer brewers, but it doesn't seem to be widely adopted in Japan.

While it is possible to purchase it in Japan, it was about 10,000 yen cheaper to buy it from America, so I ordered it, but it took about two months to arrive.

Centralized Management of All Data in Google Sheets

All data from the koji room, moromi, and TILT collected by ESP32 is automatically sent to Google Sheets via Wi-Fi.

By accumulating data in the cloud-based spreadsheet, we can check the status from a smartphone or computer even when not at the brewery.

Furthermore, with all process data gathered in one place, it has become easier to compare with past brewing batches.

Determining "Optimal Timing" Based on Data

As numerical data accumulates, sake brewing becomes more reliable.

At our brewery, we manage the data uploaded to the spreadsheet by monitoring it and continuously maintaining optimal conditions.

We can now detect and respond to changes at an early stage, such as whether the product temperature is rising too high, or if the CO2 generation rate is as expected.

Then, by combining the conditions indicated by the data with the artisans' experience, we determine the timing to finish koji production (dekoji) and fermentation at the appropriate moment.

While IoT doesn't replace the artisan's intuition, I believe it's a tool to back up years of cultivated experience with objective data, making it more certain.

The Future of Sake, Created by the Fusion of Tradition and Technology

I have never worked in a sake brewery and have almost no brewing experience, but precisely because of that, I believe I can approach sake brewing from a different perspective, completely disregarding what has been considered conventional wisdom.

Even for sake brewing incorporating IoT, it's something that traditional toji might not even conceive of, or they might think, "It would be convenient if we could do it, but it's impossible for us." But we adopted it at our brewery.

In reality, with equipment costing a few thousand to a few tens of thousands of yen and one's own effort, work can become easier, but experience often gets in the way of seeing that.

Our koji room might be seen by established sake breweries as something like, "What is this?!" but as long as the critical aspects are covered, the same quality product can be made.

Until now, systems adopted by major manufacturers were out of reach for small-scale breweries like ours, but now we can build similar systems, albeit on a different scale.

Moreover, IoT doesn't just stop at quality stabilization.

By retaining data from all processes, "the reasons why good sake was made" can be carried over to the next batch.

In the world of skilled artisans, where the transmission of experience is often difficult, this holds great significance.

We preserve traditional techniques while further refining them with new technology.

Please try a bottle of sake brewed while facing the data.

Our brewery will continue to challenge next-generation sake brewing.