Age verification
Are you 20 years old or older?
From the Front Lines of Precision Sake Brewing: A Small Brewery's Challenge with Arduino and TILT
on May 03 2026
Sake brewing has always been said to rely on the "brewer's intuition."
Indeed, experienced kurabito (brewery workers) use all five senses to detect subtle changes in the brewery, such as humidity, temperature, the frothing of the moromi (fermenting mash), aroma, and specific gravity.
However, in a small-scale brewery managed by a single person, it's impossible to be present 24 hours a day.
Therefore, in my brewery, I've introduced IoT to support my intuition.
Why manage brewing with IoT in the first place?
Today, I'll talk about the system and the newly adopted hydrometer, "TILT."
Sake brewing, especially the management of moromi, is a continuous process of tracking changes in values such as temperature, humidity, CO2 concentration, and specific gravity.
These can fluctuate significantly in just a few hours, and missing the right timing directly impacts the flavor.
In large sake breweries, it's standard practice to constantly monitor these values with dedicated equipment.
On the other hand, many small and medium-sized local breweries still rely mainly on "humans periodically entering the brewery to take measurements."
There's no doubt that sake brewing relies on the eyes and hands of artisans. However, for a one-person brewery, even "periodic measurement" can be practically difficult at times.
This is where Arduino, a small microcontroller, comes in handy.
Overall System: Arduino × Wi-Fi × Google Spreadsheet
The IoT system operating in my brewery is by no means extravagant.
It simply combines off-the-shelf parts and stores data using free cloud services.
Yet, the peace of mind it provides when I'm away from the brewery is entirely different.
By the way, the device with many wires plugged into it on the top left of the photo is an ESP32 Arduino. Power is supplied from the USB charger on the right, and the square object on the bottom left is an SSR (Solid State Relay), which acts as a switch to activate a ventilation fan (Lossnay) when a certain CO2 concentration is reached.
As I mentioned in the section on koji making, I've set up a system that automatically turns power ON/OFF when certain temperatures or concentrations are reached.
My brewery's IoT configuration
- Microcontroller: Arduino (small microcontroller board with Wi-Fi)
- Sensors: Various sensors for moromi temperature, room temperature/humidity, CO2 concentration, and specific gravity
- Communication: Data transmission to server via in-brewery Wi-Fi
- Server: Google Drive
- Recording: Automatic writing to Google Spreadsheet every minute
The key point is that records are kept minute by minute.
In koji making and moromi management, overlooking something for just a few hours can be fatal.
Opening the spreadsheet allows me to view all past transitions at a glance and instantly generate graphs.
Even when I'm away from the brewery, the peace of mind of being able to check the status on my smartphone is invaluable for a one-person brewery.
By the way, the sensor in the image is a CO2 sensor, and the black one behind it is a temperature and humidity sensor.
The process of monitoring koji making with IoT is explained in detail in a previous article.
Being able to see the temperature changes during koji production in real-time has greatly eased my mind compared to when I used to wake up many times during the night.
Please feel free to read that as well.
New addition: Hydrometer "TILT" introduced
This time, we've welcomed a new addition to the brewery: the "TILT" hydrometer.
This excellent device simply floats in the moromi and measures specific gravity and alcohol progression from its tilt, sending data via Bluetooth.
It's well-known in the craft beer world, but its use in sake breweries is still uncommon.
Until now, we could track moromi temperature and CO2 concentration in real-time, but to understand what was happening inside the moromi, we still had to scoop it out with a ladle and use a hydrometer.
With the introduction of TILT, that task is now automated, allowing us to view the moromi's fermentation curve as a continuous graph.
By comparing daily sample analysis with TILT's continuous data, we can grasp the moromi's behavior comprehensively.
I believe this will lead to more accurate and reproducible brewing.
The data in the image is for viewing on a smartphone.
Since it's an American product, the temperature is displayed in Fahrenheit.
When viewing on a smartphone, converting from Fahrenheit to Celsius requires the calculation: (degrees F - 32) × 5/9 = Celsius. However, the Arduino performs this calculation before sending the data to the server, so it's conveniently converted to Celsius in the spreadsheet.
Differences in "monitoring level" between large and small breweries
As I mentioned at the beginning, large sake breweries should be doing this level of monitoring as a matter of course.
Some even have systems with sensors in each tank, allowing a central control room to oversee everything.
On the other hand, examples of small breweries like mine doing this much are probably still few.
Many small and medium-sized breweries continue with the traditional style of kurabito making rounds at set times to take measurements.
This is by no means a bad thing; in fact, the skill of reading the brewery with the five senses is invaluable.
However, in my case, there's the reality that I have to handle all processes by myself.
Delegating tasks that I can't manage to machines, and focusing my attention on moments that truly require my judgment. For this division of labor, IoT makes a lot of sense.
To be honest, I just "wanted to do it" too
I've written a lot of plausible things so far, but half of it is a facade. The other half, the honest truth, is simply that "I wanted to do it" (laughs).
In the past, writing Arduino code or linking servers and sensors required a certain level of specialized knowledge.
However, now, if you consult AI, code and network settings can be put together in no time.
The excuse that "the technical hurdles are too high" is no longer valid.
So I can do it. So I do it.
Continuing the artisan's handiwork in the brewery while also actively incorporating new technologies.
A brewery where classic and modern coexist – I believe this is the form that a one-person brewery can strive for.
*This is the temperature and humidity sensor, and the golden object behind it is the CO2 sensor.
The wire visible on the right passes through the aluminum square pipe and goes to the ESP32 where many wires are connected.
Summary: Brewing sake with both intuition and data
A craftsman's intuition is a genuine skill born from years of experience. I have no intention of denying that.
However, if there is objective data to support that intuition, judgments become more certain, and reproducibility increases.
Arduino, TILT, Google Spreadsheet. These are all common tools.
Nevertheless, they are certainly useful in a one-person brewery. I will continue to share bits and pieces of the daily life of the brewery and the behind-the-scenes of craftsmanship.
This blog chronicles the daily life of a sake brewery. We share records of fukuro-tsuri (bag hanging), hi-ire-free (no pasteurization), and sake brewing using local Kishiwada ingredients.
Next time, we plan to deliver an analytical article comparing the moromi data obtained from TILT with the actual taste.
