Rare Blog of a Novice Brewer

For our first craft brew, we took on the challenge of a three-stage fermentation plus additional ingredient method using strawberry juice. We'll detail the entire brewing process, from a small 15L batch and 9 days of temperature control to the final bagging, along with the brewing record until Yamane Brewery's president praised it as "a perfect 100 points."

Decomposition and Fermentation: There's Only One Difference "Decomposition" and "fermentation" are, scientifically speaking, exactly the same phenomenon. Both refer to the process where microorganisms attach to food and break down and alter its components.So what's the difference? The answer is simple: whether it's beneficial to humans, and that's it. I used to eat expired natto and cheese, thinking they were made by decomposition anyway, and ended up with stomach aches. No matter how beneficial the bacteria are said to be, it's possible that non-beneficial bacteria have attached themselves later, turning fermentation into decomposition. So, I should be more moderate with expired foods. Fermented foods like natto, cheese, miso, and soy sauce transform into foods that are beneficial for our bodies, with enhanced umami and nutritional value, thanks to the action of specific bacteria. On the other hand, when food forgotten in the back of the refrigerator "goes bad," wild bacteria are also actively at work. However, because the outcome is harmful to humans, it's called "decomposition."In other words, fermented foods can be seen as the culmination of human wisdom, having carefully selected "beneficial decomposition" over a long period of time. Common Mechanisms in Fermented Foods like Sake, Bread, and Cheese Understanding the mechanism of fermentation changes how you view everyday foods. When brewing sake, the term "kamosu" (to brew) is used.First, koji mold breaks down the starch (carbohydrates) in rice into sugar, and then yeast ferments that sugar into alcohol. This two-stage process produces that rich aroma and flavor.Bread is similar. Yeast consumes the sugars in flour, and the carbon dioxide gas produced in this process causes the dough to rise. "Secondary fermentation," where the shaped dough rises again, is also due to the action of the same yeast.The fluffy texture of baked bread can be said to be the result of the activities of unseen microorganisms. Cheese and natto are also products where specific microorganisms like lactic acid bacteria and natto bacteria have transformed the raw ingredients.The fundamental principle in all of them is the same: "bacteria breaking down organic matter." The "Life-Threatening Tastings" of Our Ancestors Created Today's Food Culture A symbolic episode of this is the origin of natto. A person in extreme hunger ate beans that had spoiled in the scorching sun, and surprisingly found them delicious.This is said to be the beginning of natto.It was precisely because it was a situation one would normally avoid that an accidental discovery was made. The Miraculous Moment the World's Oldest Alcohol, "Mead," Was Born Mead (honey wine) is indispensable when talking about the history of fermentation.It is known as the world's oldest alcohol, predating wine and beer, dating back approximately 8,000 to 10,000 years. There's a theory about its origin: a wild beehive fell into a puddle, and natural yeast attached to it, leading to natural fermentation.Someone accidentally passing by noticed the fragrant aroma, approached, and found a liquid mixed with honey. Normally, you wouldn't dare drink liquid from a puddle when you don't know what's in it, would you? It could even be animal urine... However, that person was apparently so intensely thirsty that they were resigned to death.Thinking, "I'm going to die anyway," they drank it and found it surprisingly delicious, experiencing the pleasant sensation of intoxication for the first time. This is said to be the beginning of mead, and by extension, humanity's encounter with alcohol. As this anecdote, which overlaps with the story of natto's discovery, suggests, many great discoveries in human food culture may have originated from chance encounters in extreme conditions. The Origin of "Honeymoon" Lay in Mead There's another interesting anecdote related to mead.That is the etymology of "honeymoon." In ancient Europe, there was a custom where newly married couples would gather honey themselves, brew mead, and serve the finished drink to family, friends, and acquaintances. Since mead takes about a month to mature, the first month after marriage is said to have become known as the "honey moon." Honey has long been a symbol of "fertility, prosperity, and love," and it seems that newlywed couples drinking mead also expressed a wish for a harmonious marriage and many children. It's deeply moving that such a warm culture of sharing carefully brewed alcohol with loved ones remains worldwide as the term for modern "honeymoon trips." From Kura-Tsuki Yeast to Kyokai Yeast: Technological Innovation in Sake Brewing In sake brewing, too, there is a history surrounding yeast, the main actor in fermentation. In old sake breweries, instead of sourcing yeast externally, they utilized "kura-tsuki yeast," which naturally inhabited the land and buildings of the brewery. It wasn't sold anyway (laughs). The unique yeast strains produced by the local climate, natural features, and building structures created the distinctive flavors of each brewery. The turning point came in the Showa era. The Brewing Society of Japan was established and collected and analyzed superior yeast from sake breweries across the country, successfully cultivating high-quality yeast strains.A system was then put in place to provide this "Kyokai yeast" to breweries nationwide. This initiative is said to have improved the overall quality of sake and significantly reduced inconsistencies in taste. The ability for any brewery to produce consistently high-quality sake greatly contributed to the spread and development of sake culture.However, some toji (master brewers) and breweries continue to adhere to kura-tsuki yeast or self-cultivated yeast, going against this trend. The attitude of not purchasing yeast from the association, but rather cultivating yeast by their own hands and imbuing the sake with characteristics unique to that land, can be seen as an attempt to preserve the essence of fermentation culture. A Long, Long Collaboration Between Microorganisms and Humans From the origin of natto to the world's oldest alcohol, mead, and up to modern sake brewing, the history of fermentation is a long history of collaboration between humans and microorganisms. Tiny, unseen microbes have transformed ingredients, created beverages, and fostered culture.We are able to enjoy these benefits thanks to our ancestors who, through countless stomachaches, identified and passed down "beneficial fermentation."The glass of sake you hold today is filled with such an ancient history of fermentation. Of course, I can only be grateful that I can brew sake thanks to the history cultivated by my predecessors.  

Managing the Koji Room with IoT! "Koji" is a crucial element indispensable for sake brewing. The quality of koji directly impacts the taste of sake, so it's no exaggeration to say that sake brewing is koji making. As the quality of sake depends on the temperature control of the koji room (kojimuro), we have introduced a self-made temperature control system in our koji room to achieve a more precise koji production environment. Here, we will introduce the mechanism and the process leading up to its implementation in detail. Why Temperature Control in the Koji Room is Important In sake brewing, koji plays a central role in fermentation. The enzymes produced by koji mold proliferating on rice convert starch into sugar, which eventually leads to alcohol fermentation. In the koji room where koji is cultivated, temperature, humidity, and carbon dioxide concentration significantly influence the quality of the koji. Especially for sake koji, temperature control is much more critical compared to koji used for miso or soy sauce.If you take your eyes off it for even a moment and the internal temperature rises too much, the koji mold can die or unwanted bacteria can grow, ruining the precious koji. To consistently produce high-quality koji suitable for sake brewing, meticulous 24-hour management is essential. In the past, when precise temperature control was not as advanced, koji production relied on human effort. From seeding to final koji, frequent movement between locations was necessary to monitor the growth environment and manage the temperature. The Reality That Commercial Koji-Making Machines Cannot Cope With There are specialized machines for making koji, called koji-making machines.They have a relatively simple mechanism that combines a constant temperature environment with heaters, automatically managing the koji room environment. Household versions can be found for tens of thousands of yen, but for sake brewing, koji is sometimes needed in units of 100 kg, so a machine of a certain scale is required. Even a simple commercial koji-making machine costs about 200,000 yen, and a high-performance machine that can perfectly control temperature and even produce a special type of koji called "tsuki-haze" used for Daiginjo sake costs a whopping 4 million yen per unit. Tsuki-haze refers to a state of koji where the hyphae of the koji mold spread only on the surface of the rice grains and do not penetrate deeply inside. It is an essential technique for brewing refined and smooth-tasting Daiginjo sake. While high-performance koji-making machines are excellent in that they can automate this management, they are simply out of reach for a small brewery like ours. Moreover, our brewery is a renovated private house. It's questionable whether large machinery could even be brought in through the entrance, so it was immediately rejected. First, I DIYed a Koji Room I built a wooden frame in a one-tatami mat space, enclosed it with insulation, applied FRP (fiber-reinforced plastic) for waterproofing, and installed a door. Paint might seem suitable for waterproofing, but it releases organic solvents during drying, and it's unclear how long it continues to do so, so it was rejected. On the other hand, FRP is used in brewing tanks, so there's no problem, and I'm already familiar with handling FRP, so I adopted it. Also, by installing shelves inside, the koji room's basic functions are fully established, and the production cost was only about 10,000 yen for materials, which could be sourced from a local hardware store. Inside, I ran electricity and installed LED lights. Initially, I tried managing it by manually controlling the heater's ON/OFF while checking temperature, humidity, internal temperature, and CO2 concentration on my smartphone using SwitchBot. This method had a major problem. Since someone had to check it regularly, if a check was inadvertently delayed, the internal temperature would rise too high, ruining the koji. Although it was partly due to my own inexperience in koji production, the lack of precision in temperature control directly led to poor koji quality. With this, it was impossible to produce koji suitable for sake brewing. Solved with IoT! Automatic Temperature Control System using Arduino (ESP32) The solution I came up with afterwards was IoT (Internet of Things) technology.I was originally interested in microcontroller control but hesitated because I couldn't write code, but with the advent of AI, the barrier suddenly lowered. So I adopted "Arduino," an open-source microcontroller board. It's a marvel used worldwide as an introductory tool for electronics, capable of reading sensor values and controlling external devices by programming it. Raspberry Pi is also famous for similar purposes, but its price has increased recently due to performance improvements. Therefore, I chose "ESP32," an Arduino-compatible board that can be purchased for about 2,000 yen on Amazon. Despite its compact size, it has built-in Wi-Fi communication capabilities, making it ideal for IoT projects.Sensors can also be acquired for around 1,000 to 5,000 yen each, so even with an internal temperature sensor, a temperature/humidity sensor, and a CO2 sensor, the total cost is about 10,000 yen. Adding the cost of building the koji room, a full-fledged smart koji production system was completed for a total of approximately 20,000 yen. System Mechanism The current koji room management system operates as follows:Each sensor connected to ESP32 constantly measures the internal temperature, room temperature/humidity, and CO2 concentration, and automatically transmits and records data to a server (Google Sheet operated on Google Drive) every minute via Wi-Fi. The accumulated data can be checked in real-time on a computer and also on a smartphone.When the internal temperature is low, the heater automatically turns ON to raise the room temperature.When the internal temperature rises, the system maintains the optimal temperature range by frequently turning the heater ON and OFF. This is arguably a function equivalent to the temperature control performed by expensive koji-making machines. The program is written in C++ language, but since I had never written a single line of code, I relied on Google's generative AI, "Gemini" (laughs).It's amazing how modern AI tools have made it possible for someone like me, who can't program, to build an IoT system. Thinking back 40 years ago, when I was in high school and taking computer classes, the teacher said that the more digits of pi you used, the more beautiful the circle became, and all I could say was "Oh, really?" It's an incredible evolution since then. Changes After Implementation Since activating this system, the koji management process has undergone significant changes.The biggest change is no longer needing to wake up in the middle of the night to check the koji's internal temperature. Furthermore, by observing the data trends, we can now predict when maintenance is needed, virtually eliminating late-night work. The quality of koji has also stabilized, allowing us to consistently produce koji of a standard suitable for sake brewing. While it certainly doesn't compare to a 4 million yen koji-making machine, reaching this point with an investment of 20,000 yen has been a highly meaningful endeavor for our small brewery. By combining traditional sake brewing techniques with modern IoT and AI technology, even small breweries can strive for quality improvement. This system demonstrates such potential. We will continue to accumulate data and pursue even better sake brewing in the future.  

"Why such an inefficient method?" is a question I'm often asked. When I talk about our method of pressing sake, I'm almost always asked: "Doesn't the 'fukuro-tsuri' method (hanging sake bags) cut into your profits?"Honestly, it does. Yet, we still choose the fukuro-tsuri method. There's a reason for it. Let me explain it to you without reservation. First, what is "pressing"? At the final stage of sake brewing, there's the process of pressing sake from the moromi (sake mash). The most common method is "pressing." The moromi is put into sake bags, stacked in a machine, and strong pressure is applied from above. It's pressed gradually until it's completely flat. Eventually, the sake bags become as thin as boards, taking on the shape of "itakasu" (pressed sake lees boards) often seen in spring. As a child, my mother would grill itakasu on a kerosene stove and sprinkle it with a generous amount of sugar for me to eat. The word "sake" made me feel like I was becoming an adult, which made me happy. The advantages of pressing are clear. Aside from the deliciousness of grilled itakasu (laughs). First, it's efficient. It's machine-operated, requiring less labor and time. Next, it has a high yield. About 80% of the moromi becomes sake, and the remaining 20% becomes sake lees. By pressing out as much as possible, the maximum amount of sake is obtained from a single batch. It's suitable for mass production and allows for stable quality control. It's a highly rational decision for large breweries to adopt pressing. So, what is "fukuro-tsuri"? The fukuro-tsuri method is a completely different approach. Moromi is placed in sake bags and hung, allowing only what naturally drips down due to gravity to be collected as sake. No pressure is applied whatsoever. It's simply hung, and we wait. That wait is about 24 hours. As a result, the amount of sake obtained is only about 50% of the total moromi. The remaining 50% is sake lees. Compared to pressing, the yield is almost half. While it doesn't require large machinery, it does take time and effort. From a purely business perspective, there is no pressing method that is more "unprofitable." In fact, many sake breweries that use the fukuro-tsuri method do so only for entries in competitions or for special limited-edition products, and do not use it for their regular commercial sake. Still, the one and only reason we choose fukuro-tsuri Because it tastes overwhelmingly better. That's all there is to it. In the moromi stage, not all of the rice starch has completely converted to alcohol. Some parts are completely dissolved, some are half-dissolved, and some still retain their original shape. In other words, "components that couldn't quite become sake" coexist. When pressing with strong force, not only the true sake but also these "unconverted components" are squeezed out together. This is the source of off-flavors. Pressing isn't inherently bad. However, the more force applied, the more non-sake components get mixed in. Fukuro-tsuri relies solely on gravity. Only what naturally drips down is collected. Therefore, only the parts that truly wanted to become sake gently drip down. As a result, there's no room for off-flavors, creating a mellow and well-defined taste that is truly sake. What large breweries can do and small breweries cannot, and vice versa. Large sake breweries produce a year's worth of sake during the winter. Moromi brewed in multiple tanks is eventually blended to balance the flavors. This is a strength of large breweries and also a skilled craft. However, the sake made by a Toji (master brewer) is mixed by a blender, which can, on the other hand, eliminate the unique originality. Yet, through blending, some off-flavors from pressing are neutralized as complex flavors when mixed with components from other tanks. When a skilled blender adjusts it, off-flavors cease to be off-flavors. However, in small breweries like ours, a single batch is at most a few hundred liters. We don't even have the scale to have multiple tanks for blending. We lack the quantity and diversity to transform off-flavors into complex aromas. If that's the case, there's only one answer. Don't produce off-flavors in the first place. Being small-scale is not a limitation but an option. Precisely because we cannot mass-produce, the time-consuming and labor-intensive fukuro-tsuri method can become a realistic choice. It's a method that large breweries absolutely cannot implement across all their products, but a small brewery can. This is our unconventional approach. The meaning of choosing it despite knowing the disadvantages A yield of 50%. Half the amount compared to pressing. It takes time. Profit margins decrease. Still, choosing fukuro-tsuri is not about profit and loss. It's simply about delivering truly delicious sake to those who drink it. The first time I tasted sake pressed with fukuro-tsuri, I felt, "This is what sake is supposed to taste like." Nothing extraneous. Without off-flavors, the sweetness and umami of the rice come straight through. Mellow, yet with a distinct character. Once I experienced that taste, there was no going back. It's not profitable, but I can't stop. That's the kind of sake it is. Please try our fukuro-tsuri sake at least once.

Introduction: "Rice Koji" is the Foundation of Japanese Food Culture Sake, miso, soy sauce, mirin, shio-koji, amazake – none of these would exist without "rice koji." Rice koji is the unsung hero that supports Japan's food culture, a nation of fermented foods. As a sake brewery, we prepare a large amount of rice koji every year. Koji-making is not merely a manufacturing process; it's a dialogue with microorganisms called koji mold, and the very essence of craftsmanship passed down through generations. It is said that the process of koji making is where humans assist koji mold to create a comfortable environment for it to grow, as the seed koji attaches to the surface of steamed rice, extending its hyphae towards the internal moisture and proliferating on the surface. The Difference Between 麹 and 糀 Both characters represent koji mold and are often used interchangeably depending on the context. ･糀 is a Japanese-created kanji character, derived from the appearance of koji mold blooming like a "flower" on steamed rice. It often specifically refers to "rice koji" used in making miso and soy sauce. ･麹 is a kanji character introduced from China, often representing koji from all grains, and is primarily used in sake brewing. What is Rice Koji? Definition and Basic Knowledge Koji Mold "Aspergillus oryzae" Rice koji refers to steamed rice on which koji mold (Aspergillus oryzae) has been propagated. Koji mold is a type of fungus, but it is not only harmless to humans but also known as a beneficial microorganism essential for food fermentation and brewing. It is also a microorganism indigenous to Japan, and on October 12, 2006, it was recognized as Japan's "national fungus" by the Brewing Society of Japan. From an academic perspective, the genome of Aspergillus oryzae was sequenced in 2005 (by the National Institute of Advanced Industrial Science and Technology), and it was found to possess approximately 12,000 protein-coding genes. Compared to its close relative, A. flavus, koji mold has genes that produce toxic aflatoxins silenced (inactivated), confirming its high safety at the genetic level (Machida et al., 2005, Nature). In other words, koji mold is "a safe and excellent microorganism that Japanese people have selected and cultivated over a long history," and it does not naturally exist in environments outside of Japan. The "Power of Enzymes" Created by Rice Koji - The Most Important Function for Breweries For sake breweries, the greatest value of rice koji lies in its being a treasure trove of enzymes. As koji mold extends its hyphae, it secretes a wide variety of hydrolytic enzymes. Amylase = Converts starch into sugar. Amylase is an enzyme that breaks down starch (polysaccharides) into glucose and maltose. In sake brewing, this reaction enables a unique fermentation process called "multiple parallel fermentation." Beer undergoes sequential fermentation, where barley starch is saccharified before fermentation. Wine is made by fermenting grapes, which are naturally rich in sugar. In sake, the saccharification of rice starch by koji and the alcoholic fermentation by yeast proceed simultaneously. This multiple parallel fermentation is one of the reasons why sake achieves a high alcohol concentration of nearly 20 degrees while possessing complex and delicate flavors. Protease = Converts protein into amino acids Protease is an enzyme that breaks down proteins into amino acids. Amino acids such as glutamic acid, which are at the heart of sake's "umami," are produced by the action of this protease. Sake breweries often use the term "koji no chikara" (power of koji), which precisely refers to the strength of these enzymatic activities. If the koji's power is too strong, the sake becomes too sweet; if it's too weak, fermentation doesn't proceed. The koji master discerns this delicate balance through decades of experience and intuition. Lipase, Cellulase, etc. Koji mold also produces various other enzymes such as lipase, which breaks down lipids, and cellulase, which breaks down cellulose. These act in combination to create the diverse flavors and nutritional value of fermented foods. Koji Making Process: The Craft of the Sake Brewery Koji Production Process ① Selection and Polishing of Raw Rice Good koji starts with good rice. Sake-brewing suitable rice varieties like Yamadanishiki and Gohyakumangoku have a shinpaku (white core), a central starchy part, which makes it easy for koji mold to propagate. Since the polishing ratio also affects the quality of the finished koji, this step is extremely important. ② Washing, Soaking, and Steaming The polished rice is washed, soaked in water for an appropriate time, and then steamed in a steamer (koshiki). The ideal steamed rice is "gaikou nainan" (hard on the outside, soft on the inside). This allows the koji mold to easily extend its hyphae into the interior. ③ Spreading Seed Koji After cooling the steamed rice to an appropriate temperature (approx. 35-40℃), seed koji (spores of koji mold attached to a carrier) is sprinkled evenly. Currently, seed koji is manufactured and sold by specialized業者 called "moyashi-ya" (seed koji makers), with a history dating back to the Muromachi period. ④ Management in the Koji Muro: The True Skill of the Craftsman In the koji muro, where temperature and humidity are strictly controlled (35-40℃, approx. 90% humidity), the hyphae are propagated over approximately 48 hours. During this time, brewers "teire" (tend to) the rice by hand every few hours to equalize the temperature and control the growth of the hyphae. Entering the koji muro at 2 or 3 AM is a reality of sake brewing. To make good koji, "sleepless vigilance" is literally required at times, and the brewers' hands are always warm, imbued with the sweet aroma of rice. The optimal temperature for koji mold growth is approximately 30-35°C for hyphal growth and 25-30°C for spore formation. While master brewers of the past understood this through experience, our brewery manages the optimal timing for tending and room temperature by managing data with IoT. Health and Nutritional Benefits of Rice Koji: The Scientifically Proven Blessings of Fermentation In recent years, rice koji has also gained attention as a health food. Production of Vitamins and Essential Amino Acids Through the metabolism of koji mold, B vitamins (B1, B2, B6, niacin, etc.) are produced. Furthermore, the amino acids produced by proteases include essential amino acids, increasing its nutritional value. Presence of Functional Peptides Fermented foods derived from koji have been reported to contain ACE-inhibitory peptides that have blood pressure-lowering effects (Itou & Akahane, 2004, and others). Scientific evidence like this is behind the attention given to shio-koji and amazake as health foods. Reference: From the Consumer Affairs Agency's "Status of Analysis after Notification of Foods with Function Claims" Impact on Gut Environment Polysaccharides and peptides derived from koji mold in koji-fermented foods are suggested to contribute to the improvement of the gut microbiome (gut flora). With the recent advances in gut microbiome research, the focus on the functional properties of fermented foods is further increasing. Types and Uses of Rice Koji: Explained from a Sake Brewery's Perspective The properties of koji vary greatly depending on the strain of koji mold and culture conditions. Yellow Koji (Kikouji): The Main Player in Sake, Miso, and Soy Sauce This is the most widely used koji. Since it produces less citric acid, it results in sake with low acidity and delicate, fruity characteristics during brewing. White Koji (Shirokouji) and Black Koji (Kurokouji): Giving Shochu its Character Koji traditionally used in shochu brewing in Okinawa and Kyushu regions. It produces a large amount of citric acid, which is effective in preventing contamination by miscellaneous bacteria. Black Koji (Aspergillus luchuensis) is the traditional koji for Awamori, and white koji was discovered as a mutant strain of it. In recent years, there have been increasing efforts to apply white koji to sake brewing, and "white koji-brewed sake" with a sharp acidity different from traditional yellow koji has become a topic of discussion. The Future of Koji Making from a Sake Brewery's Perspective I believe that traditional handcrafted koji-making will continue to retain its value. However, at the same time, advancements in science and technology also offer new possibilities for koji research. Research on improving functionality using koji mold genome information, and at our brewery, while various sensors manage temperature and humidity, major companies are developing automated koji muro management systems utilizing AI and sensor technology. The integration of tradition and innovation is progressing. What we value is using our hands with a scientific understanding. We trust the numbers displayed by temperature sensors and data loggers, but ultimately, we make judgments by smelling the koji, touching it with our hands, and observing its color. That is the job of a sake brewery's master brewer. Conclusion: Rice Koji is a "Living Cultural Asset" Rice koji is not merely a tool for fermentation. I believe it is a "living cultural asset" that has been cultivated over hundreds of years in Japan's climate and passed down from craftsman to craftsman. Koji mold Aspergillus oryzae is Japan's "national fungus," with its safety and functionality proven at the genomic level. Rice koji supports the world's only brewing technique of multiple parallel fermentation, producing the taste, aroma, and nutrition of fermented foods through its rich enzyme group, including amylase and protease. Koji making is a precise technique that combines the management of temperature, humidity, and time with the five senses of the craftsman, and scientific research on its health functional properties is also rapidly progressing. For a sake brewery, koji is the "beginning of brewing" and the "life of sake." Next time you pick up sake or miso, I hope you will give a little thought to the work of the koji masters behind it and the unseen activities of the microorganisms.

Sake, doburoku, and nigorizake — they seem similar but are completely different. This article thoroughly explains the differences between the two categories defined by the Liquor Tax Act, based on their production methods, ingredients, and shipping requirements. 1. "Sake" and "Other Brewed Alcoholic Beverages": What are the distinctions under the Liquor Tax Act? In Japan, the manufacturing and sale of alcoholic beverages are strictly regulated by the Liquor Tax Act. Please note that manufacturing or selling without a license is a legal violation. The Act broadly classifies alcoholic beverages into four types: "Sparkling Alcoholic Beverages," "Brewed Alcoholic Beverages," "Distilled Alcoholic Beverages," and "Mixed Alcoholic Beverages." Within brewed alcoholic beverages, there are further categories such as "Sake," "Synthetic Sake," "Fruit Wine," and "Other Brewed Alcoholic Beverages." Most of what is generally referred to as "Japanese sake" falls under the legal definition of "Sake" under the Liquor Tax Act. Other beverages, such as what is commonly known as "doburoku" and certain fermented drinks, may be classified as "Other Brewed Alcoholic Beverages." These two categories, while seemingly following similar production methods, are fundamentally different in terms of the requirements stipulated by the Liquor Tax Act. These differences are summarized along three axes: "Filtration Obligation," "Additives Regulation," and "Range of Ingredients." Liquor Tax Act, Article 3 (Excerpt and Summary) Sake refers to an alcoholic beverage made by fermenting rice, rice koji, and water, which has been filtered, and has an alcohol content of less than 22 degrees (addition of sugars, organic acids, etc. is permitted under certain conditions). Reference: National Tax Agency, Interpretation of Laws, Article 3, Definition of Other Terms What is noteworthy here is the phrase "has been filtered." To be shipped as sake, the moromi (mash) must always be filtered. This is the fundamental difference from "Other Brewed Alcoholic Beverages." 2. Main Differences ①: Whether there is an obligation to filter moromi (mash) In sake production, the stage where rice, rice koji, and water are prepared and fermented is called moromi. If this moromi remains as is, it is "doburoku (turbid moromi)." Incidentally, while moromi cannot be filtered in the case of other brewed alcoholic beverages, if it has separated into clear liquid and sediment over time, simply scooping out the clear liquid is considered filtration. Sake Filtration is a mandatory condition Under the Liquor Tax Act, moromi must be filtered to be manufactured and shipped as "sake." Separation of rice solids (sake lees) and liquid (sake) through filtration is a legal requirement. Shipping in doburoku form is not permitted under a sake license. Other Brewed Alcoholic Beverages Can be shipped without filtration With a license for "Other Brewed Alcoholic Beverages," moromi can be shipped as a product in its unfiltered doburoku or turbid state. The recent "Doburoku Special Zone" system also utilizes this category. This regulation has a significant impact on practical operations. For example, when farm stay operators or small local businesses utilize the "Doburoku Special Zone" system to manufacture and sell doburoku, they often obtain a manufacturing license for "Other Brewed Alcoholic Beverages." While a sake license requires moromi to be filtered to a clear state before shipping, a crucial reason is also that new brewing licenses for sake, shochu, and mirin are not currently being accepted. Furthermore, this difference directly affects the appearance of the product. Filtered sake generally results in a transparent to pale yellow liquid, whereas doburoku, classified as other brewed alcoholic beverages, is sold in a cloudy, white state. Recently popular "nigorizake" belongs to the sake category. This is because it satisfies the "filtered" requirement by either intentionally adding back a small amount of sediment after initial filtration, or by using a coarser filter cloth to leave a trace amount of solids. 3. Main Differences ②: Regulations regarding additives during fermentation Another important axis distinguishing sake from other brewed alcoholic beverages is the range of ingredients and additives that can be introduced during fermentation. Sake Strict restrictions on additives during brewing During fermentation (brewing process), only items listed by the Liquor Tax Act can be added. Primarily rice, rice koji, and water, with sake lees, brewing alcohol, sugars, organic acids, amino acids, etc., permitted only under certain conditions. In principle, "unlisted" ingredients such as agricultural products cannot be added during fermentation. Other Brewed Alcoholic Beverages Relatively flexible with additives during fermentation Other brewed alcoholic beverages can be manufactured by adding ingredients "other than rice, koji, and water"—such as fruits, vegetables, herbs, dairy products—during fermentation. This allows for the creation of craft-style fermented beverages with unique flavors, while still being sake-based. In sake, the ingredients that can be used for brewing are explicitly stipulated by the Liquor Tax Act. For example, directly adding yuzu or plums to the fermenting moromi is not permitted under a "sake" manufacturing license (if fruit juice is added to finished sake, the category becomes liqueur, requiring a different license). On the other hand, in the category of other brewed alcoholic beverages, it is sometimes possible to incorporate such "unusual ingredients" into the fermentation process, which has gained attention amid the recent craft fermented beverage boom. For example, fruit doburoku, which adds fruits during fermentation while based on rice and koji, is one such example. 4. Main Differences ③: Range of usable ingredients Sake is primarily made from "rice, rice koji, and water." The definition of sake in the Liquor Tax Act includes the phrase "made by fermenting rice, rice koji, and water, which has been filtered," which sets the minimum conditions for sake. The addition of alcohol or sugars is permitted if statutory requirements are met, but only within the scope of "sake." Key Point: Sake Ingredient Regulations (Overview) Main ingredients permitted for sake: Rice, rice koji, water, sake lees, brewing alcohol (less than 36% alcohol by volume), sugars, organic acids, amino acid salts, starch syrup, coloring agents, etc., limited to items specified by the Cabinet Order for the Liquor Tax Act. Reference: Overview of the "Sake Production Quality Labeling Standards" In contrast, "Other Brewed Alcoholic Beverages," as the name suggests, is a broad category that encompasses brewed alcoholic beverages that do not fall under the definitions of sake, synthetic sake, fruit wine, beer, etc. They can use grains and sugars as primary ingredients, and other things as secondary ingredients, such as products made with herbs or hops. 5. Comparison with specific examples Case ①: Doburoku Special Zones and direct sales from farmers With the "Structural Reform Special Zone" system initiated in 2003, farmers and farm stay operators in specific regions became able to locally produce and sell doburoku on a small scale. This doburoku is manufactured under a license for "Other Brewed Alcoholic Beverages," and due to its special zone status, there are also regulations that only doburoku can be produced. It is expanding through regional revitalization and promotion of farm stays, with special zones now existing nationwide, including Takatsuki City in Osaka. Case ②: Is nigorizake sake or other brewed alcoholic beverages? Most "nigorizake" sold commercially is classified as sake. This is because it meets the legal requirement of "filtration" by passing the moromi through a coarse cloth, a process called "arakoshi" (coarse filtration). Although it appears cloudy, it is legally filtered sake under the Liquor Tax Act. On the other hand, doburoku, which is not filtered at all, falls under the category of other brewed alcoholic beverages. Case ③: Craft sake made by fermenting rice and fruit together In recent years, craft fermented beverages have emerged that are based on rice and koji but also incorporate herbs or fruits during fermentation. Since these use ingredients outside the scope of sake's ingredient regulations in the fermentation process, they are often produced as "Other Brewed Alcoholic Beverages," and this is indicated on the label. Case ④: Junmai-shu and Honjozo-shu "Junmai-shu" is sake made only from rice, rice koji, and water, without the addition of brewing alcohol. "Honjozo-shu" is sake with a small amount of brewing alcohol added. Both are legally classified as "sake" under the Liquor Tax Act. Both undergo a moromi filtration process, making them a completely different category from doburoku; doburoku cannot be called junmai-shu. Our brewery refers to this as junmai brewing. 6. Table: Sake vs. Other Brewed Alcoholic Beverages Comparison Item Sake Other Brewed Alcoholic Beverages (e.g., Doburoku) Moromi Filtration Mandatory (legal requirement) Not required. Can be shipped unfiltered Main Ingredients Primarily rice, rice koji, water Can also use ingredients other than rice, koji, water Additives during fermentation Only legal items (strict enumeration) Relatively high degree of freedom Appearance Transparent to pale yellow (nigorizake is exceptionally cloudy) Mostly cloudy/opaque Representative Examples Junmai-shu, Ginjo-shu, Honjozo-shu, Nigorizake Doburoku, craft fermented beverages Legal Basis (Liquor Tax Act) Article 3, Item 7 (Definition of Sake) Article 3, Item 19 (Definition of Other Brewed Alcoholic Beverages) License Category Sake Manufacturing License Other Brewed Alcoholic Beverages Manufacturing License 7. Summary: What the two categories signify "Sake" and "Other Brewed Alcoholic Beverages" both share the commonality of being fermented beverages made from rice, koji, and water, yet they differ distinctly in terms of the requirements stipulated by the Liquor Tax Act. Sake is bound by two restrictions: "must be filtered" and "ingredients limited to statutory items," which serves as the institutional backing to preserve traditional sake quality. On the other hand, "Other Brewed Alcoholic Beverages" is a category freed from these restrictions, offering a more flexible manufacturing license option for farmers in Doburoku Special Zones and manufacturers creating new craft fermented beverages. Sake must always filter moromi; cannot be shipped as doburoku Other brewed alcoholic beverages can be shipped unfiltered; Doburoku Special Zones utilize this license Ingredients and additives that can be used in sake brewing are limited to those enumerated in the Liquor Tax Act Other brewed alcoholic beverages have the flexibility to add ingredients other than rice, koji, and water during fermentation Commercially available "nigorizake" is sake that has undergone coarse filtration, legally distinct from doburoku Junmai-shu, Honjozo-shu, and Ginjo-shu are all classified as "sake" When choosing sake, simply checking whether the label says "Sake" or "Other Brewed Alcoholic Beverages" can reveal the institutional framework within which the product was created. Understanding the legal mechanisms behind alcoholic beverages might just be an entry point to enjoying sake more deeply.

Sake is not just a simple "alcoholic beverage." First, it is a uniquely complex fermented beverage, starting from the starchy substrate of white rice, where multiple microorganisms divide roles to perform stepwise transformations. Let's unravel that fermentation process from the perspective of microbiology and biochemistry. 1. Koji-making Process: Building a Platform for Enzyme Production The first key to sake brewing lies in the koji-making process by Aspergillus oryzae (koji mold). It begins by scattering koji mold spores onto steamed rice that is firm on the outside and soft on the inside. The steamed rice, inoculated with tane-koji, is then cultivated in a koji room (koji-muro) with precisely controlled temperature and humidity for about 48 hours.During this time, the koji mold extends its hyphae into the rice grains and secretes a wide variety of hydrolytic enzymes. Particularly important is the production of amylases (α-amylase and glucoamylase) and proteases.α-amylase hydrolyzes the α-1,4-glycosidic bonds of starch in an endo-type manner to produce dextrin, and glucoamylase sequentially releases glucose from its ends.This two-stage saccharification reaction supplies fermentable monosaccharides to the yeast.Protease breaks down proteins into amino acids and peptides, serving as a nitrogen source for yeast in subsequent processes and acting as a precursor to umami components in sake. While using technical terms, essentially, koji mold breaks down rice, which is a lump of starch, into sugar, making it easier for the yeast in the next step to break it down into carbon dioxide and alcohol. 2. Shubo (Yeast Starter): Selection of Microbial Flora and Yeast Proliferation Next, koji obtained from koji-making, steamed rice, water, and yeast are brewed in a small tank to cultivate a high-density yeast culture solution called "shubo" (moto). In traditional kimoto and yamahai-moto methods, wild lactic acid bacteria (of the Lactobacillus genus, etc.) are naturally propagated, but this is rarely done in modern sake brewing.Instead, in the modern mainstream sokujo-moto method, instead of propagating lactic acid bacteria like in kimoto or yamahai-moto, brewing lactic acid is directly added. Homo-lactic acid fermentation by lactic acid bacteria (C₆H₁₂O₆ → 2CH₃CH(OH)COOH) rapidly lowers the pH of the moromi (main mash). This pH drop acts as a selective pressure, eliminating miscellaneous bacteria that are weak to acidic conditions, while giving an advantage to the proliferation of acid-resistant brewing yeast (Saccharomyces cerevisiae). At this stage, the yeast enters its exponential growth phase, increasing cell density in preparation for the subsequent moromi fermentation. The acidification of the moromi aims to eliminate miscellaneous bacteria that could negatively affect brewing by making the acidic environment unsuitable for their survival. In this environment, yeast, being strong against acid, can perform its function without being destroyed along with other miscellaneous bacteria. 3. Moromi Fermentation: A Globally Rare Fermentation Method Called Parallel Multiple Fermentation The greatest characteristic of sake is this concurrent saccharification and fermentation. Unlike beer, where saccharification and fermentation are separated, in sake, saccharification by koji and alcohol fermentation by yeast proceed simultaneously within the same tank. This is an extremely rare fermentation method among brewed beverages worldwide. The gradual addition of koji rice, steamed rice, and water in three stages ("hatsugoe," "nakagoe," and "tomegoe") during "sandan-jikomi" (three-stage preparation) is also to maintain the substrate concentration within an appropriate range relative to the yeast cell density and to prevent a decrease in yeast activity due to osmotic stress. Furthermore, this operation, combined with low-temperature, long-term fermentation (approximately 20-30 days), promotes the production of aromatic components (isoamyl acetate, ethyl caproate, etc.), forming a complex flavor profile. The central reaction of alcoholic fermentation is the production of ethanol via glycolysis (Emden-Meyerhof-Parnas pathway): C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. The alcohol concentration at the end of fermentation reaches 14-20%, which is close to the upper limit of the yeast's own alcohol tolerance. Ultimately, the power of yeast transformed it into carbon dioxide and alcohol through fermentation, but as the alcohol concentration increases, the yeast also dies off. 4. Joso and Hi-ire: Termination of Fermentation and Stabilization of Quality Once the moromi has matured, it undergoes a solid-liquid separation process called "joso" to be separated into sake and sake lees, resulting in clear sake. Afterward, in most cases, hi-ire (pasteurization) is performed. Even after separation from sake lees, there are still living yeast cells, so a short-time heat treatment at 60-65℃ is carried out to inactivate residual wild yeasts and lactic acid bacteria, and to deactivate enzyme activity (especially residual amylase). This concept of pasteurization, a technology uniquely developed in Japan, is said to predate Western Pasteur (named after the person who elucidated the principle of wine making from grapes) by about 300 years. Sake fermentation is a precise biological process where microbiology, enzyme chemistry, and food engineering intersect. Koji mold, lactic acid bacteria, and yeast each occupy different spatiotemporal niches and cooperate to create that clear cup of sake. Although sake is consumed worldwide, the method of sake production is uniquely Japanese, as this story explains.

How was the brand "Kimama" born? Please read the secret story behind the brand name, which conveys gratitude for the rare rice of local farmers and the desire to deliver its "unadulterated" deliciousness. This name was chosen after considering many candidates, including the classic auspicious words "Chiten Tai" from the I Ching, the Buddhist term "Uchouten," and the potter Hanjiro Kawakita's pseudonym "Kimama."

Ready to start brewing sake I thought I could start brewing sake as soon as I got my license, but preparing after getting the license has been surprisingly tough. Sake brewing involves steaming rice, mixing it with koji and water, and adding yeast, but there are countless other tasks and responsibilities.   Things that can only be done after getting the license Reporting the recipe to the tax office. Label design application Registering facility equipment Ordering reagents for analysis during brewing Ordering yeast etc For a new sake brewery like ours, we have zero approved recipes, so we have to apply for everything. Also, there are things like yeast that cannot be purchased without a license. Preparing all of that took two months. Can only use Windows For applications and declarations related to sake brewing and sales, e-Tax, an online registration system, is essential, and paper applications are frowned upon. With paper applications, the application form is mailed to a dedicated counter, where it's digitized into a PDF and then delivered to the sake department, which reportedly takes about a week. However, with e-Tax, applications can be viewed immediately, so the sake official recommended e-Tax, or rather, requested it. So, I decided to try e-Tax. Upon investigation, I found that while there are online options, applications for sake-related matters can only be done by installing software. Furthermore, it's a system where you verify your identity by reading your My Number Card with a card reader, but I don't have a My Number Card, so I wondered what to do. I found out that it's possible to proceed by preparing documents containing the company's registration information. However, this also costs about 8,000 yen for 27 months. Creating a My Number Card would take time, and I couldn't do anything during that period, so I gave up, paid the fee, and applied for the documents with the company's information. I thought this would allow me to apply, but there was another pitfall... My computer is a Mac, so that was out. Reluctantly, I borrowed my wife's computer, installed e-Tax, created an account, and completed only the minimum necessary applications. Sake brewing not only requires applications but also monthly declarations of sales performance. Borrowing my wife's computer every time would be difficult, so I gave up and looked into buying a used Windows laptop, but models from about five years ago were selling for tens of thousands of yen. Apparently, WIN11 is installed, but will it run properly? I'm also worried it might break down quickly. On the other hand, new ones cost over 100,000 yen, and those with low specs are too slow to be usable. Found a MINI-PC It's a desktop computer without a monitor, keyboard, or mouse, but if I can use it remotely from my Mac, I don't need a monitor, keyboard, or mouse to operate it from my Mac. This perfectly matches my needs. Moreover, the price is incredibly cheap at around 30,000 yen. The specs are also perfectly adequate, and it runs smoothly. Normally, I use my Mac, but when I need to use e-Tax, I just boot up this MINI-PC and make the applications. A monitor and keyboard are only needed during setup, but I used the TV as a monitor and the keyboard I used before switching to Mac. Now I can finally start as a brewer Two months passed in a flash. I was so excited about getting the license and had so many things to do that some tasks were left incomplete or inadvertently overlooked, causing time to slip by. Anyway, Sugimoto Sake Brewing is starting.  

Among food enthusiasts, the ultimate pairing whispered about is "doburoku x blue fish." This involves fatty fish like mackerel, sardines, and saury, combined with doburoku, a cloudy sake. While seemingly surprising, this combination actually has scientific and cultural backing.