Fermentation: The Gastronomic Foundation of Japanese Cuisine

By Taylor Bond

The savory, aromatic sweetness of miso. The multifaceted flavor of sake crafted from clear mountain water. The briny crunch of tsukemono pickles included in teishoku meals or offered up as otsumami small plates. None of these iconic Japanese staples would exist without the sheer transformative magic caused by fermentation.

A fermentation powerhouse, Japan has long fostered a rich culinary culture utilizing fermentation to enrich flavor, preserve ingredients, and boost health benefits. Not only does Japanese food consist of countless stand-alone dishes using fermentation as the base, but fermented sauces and seasonings also act as the hidden - yet crucial - key to enhancing the natural flavor of dishes. A slice of sashimi often feels incomplete without a dash of soy to showcase the true depth of flavor. A hearty izakaya meal is left lacking unless paired with a tokkuri of sake.

Therefore, no understanding of Japanese food is complete without a deeper examination into the essential role that fermentation plays.

The Basics of Fermentation

Anaerobic respiration processes are the basis of fermentation, occurring as the microbes break down sugar into various byproducts, all of which contribute to producing a complex yet satisfying taste. However, not all fermentation processes are the same, and they certainly do not all produce the same flavor. Acetic acid fermentation, for example, results in products like vinegar, while lactic acid fermentation produces everyday staples such as baked goods, probiotic yogurt, and pickles. Despite the basic principles of fermentation remaining constant, changes in conditions, temperature, and bacteria type can all influence the taste and aromas produced. 

Human-controlled fermentation has a long history, both globally and within Japan. The first documented accounts of this culinary practice date back to yogurt produced in North Africa in 10,000 BCE. In the Japanese archipelago, while the earliest examples of fermentation can be traced to the Jomon Period (roughly 14,000 to 300 BC), excavated wooden tablets have captured written references to fermentation as early as the Nara Period (710-194 AD) - the very start of the written Japanese language. However, as fermentation is not a human invention, but instead, a naturally occurring process, the true origins of fermentation used in food prove elusive.

Since antiquity, fermented food was been enjoyed not just as a way to extend the shelf-life of ingredients, but also for the positive health benefits provided, which include improved digestive health, a boosted immune system, and easier digestion. In Japan’s Edo Period (1603-1867 AD) fermented food played a crucial role in the diet of all different social classes due to its valuable properties, from noble samurai to the common people, with daikon radish pickles on hand in everyday homes and festive hanami dishes utilizing tsukemono cut into elaborate shapes. Even in modern times, Japanese fermented food can be found in not only the average household, but also gracing the tables of fine-dining restaurants.

Koji: The Fuel for Fermentation in Japanese Food

A strand of mold culture indigenous to Japan, koji comprises the core taste of Japanese fermented food, and accordingly, a large portion of Japanese food on the whole. From serving as the main ingredient in brewing sake, to acting as the key compound in producing richly savory miso or pleasantly salty soy sauce, this naturally occurring culture, versatile in flavor and various in application, has been used to produce an impressive range of food products within Japan.

A small seasoning with significant impact, koji coaxes out the tastes hidden within ingredients, thanks to the transformative properties of the diverse enzymes it produces. Amylase, protease, and lipase are just a few that this culinary dynamo churns out during the fermentation process. Koji also comes in multiple types, including barley koji, rice koji, and soybean koji, each of which possesses their own characteristics.

After koji has been introduced, and the initial stages of fermentation begin, a nearly limitless range of products can be crafted, contained only by one’s culinary imagination. For example, shio koji, a mixture of salt, rice, and koji, is often used as a marinade, providing a salty punch with an umami base. On the sweeter end of the spectrum, amazake is a mixture of rice, koji, and porridge that is fermented overnight, resulting in a non-alcoholic beverage with ample health benefits. 

Expert brewers can influence the taste and growth of koji by controlling the temperature and humidity of growing conditions, providing intricate complexities that can be tasted in Japanese cuisine. The historic profession of cultivating koji, or tanekoji-ya, is said to date back over 600 years, and continues unbroken even in modern times. Aside from the staunch traditionalists, who carry on the legacy of preserving both centuries-old koji colonies as well as the original production methods used by their ancestors, hobbyists have taken up the torch to experiment with new methods, creating bold new flavors. 

Microbial Cultures to Culinary Culture: Fermented Products in Japan

The conditions for fostering microbial cultures are optimal in Japan, a long country stretching north to south that encompasses a diverse range of climates and culinary practices, and also possesses high humidity levels that stimulate fermentation. These circumstances have resulted in the development of countless different iconic Japanese food products founded on fermentation.

Miso:

A product with near-limitless variability despite only using three core ingredients - soybeans, salt, and koji - miso adds a complex, robust flavor to many of Japan’s core cuisines. Variations in climate and type of koji contribute to the nuanced differences in flavor and color, as does the maturation time. Red miso, for example, has a richer flavor profile and undergoes a longer fermentation process, while white miso has a shorter fermentation period and retains a slightly more sour taste. The complexity of the flavor is worth recognition on its own, with dishes like miso soup showcasing the sheer depth included in just the ingredient itself, but also acts as a base for a variety of soups, glazes, stir-fries, and more.

• At this Akita-based miso & soy atelier that’s been brewing for over 150 years, experience fermentation, elevated to exquisite gastronomic experience. After going on a private tour of the miso and shoyu brewery and learning about the traditional production processes firsthand from the head brewer, guests can then enjoy a fine dining meal incorporating the establishment’s products and flavors to unlock a deeper appreciation for Japanese fermented cuisine.

Soy Sauce:

Traditionally, making soy sauce in Japan consisted of softening or dissolving soybeans, preparing the koji starter, and then mixing the ingredients together before undergoing a lengthy fermentation process. While more contemporary soy sauce breweries use metal containers and updated technology, some instead keep to the original practices of aging soy in wooden canisters, similar to whiskey.

Following the fermentation period, the product is pressed and pasteurized to eliminate active microorganisms and enhance the aroma, before being bottled and shipped out to sushi stalls and washoku restaurants all across Japan.

Soy sauce can be classified into 5 categories, depending on the ingredients used and the aging period. Lighter soy sauces pair well with white wine and salads, while darker ones match best with red meats and red wine. Whether dabbed onto a filet of sushi, marinating meat, or added to the base of a broth, soy sauce provides a dash of powerful, fermented flavor that doesn’t detract from other ingredients involved. 

• Private Soy Sauce Factory Tour: At this historic Hokkaido soy sauce factory, operating since the Meiji era days of settlement and exploration, observe the production process up close, and sample an array of soy sauce styles. A winner of the prestigious Minister of Agriculture, Forestry, and Fisheries Award, the fermented flavor brewed here preserves the traditional taste of Japanese shoyu.

Sake:

High-quality rice, pristine water, and koji are the only ingredients needed to craft sake, Japan’s representative alcohol. Despite the simplicity of the recipe list, the brewed final product possesses distinct flavors, including karami (dryness), nigami (bitterness), amami (sweetness), sanmi (acidity), and shibumi (tartness).

While the earliest records of sake production within Japan extend as far back as the 3rd century AD, production of sake by the Imperial Court was formally established in the 7th century, and has continued on in unbroken efforts ever since. Far more than merely an alcoholic beverage, sake has been closely tied to Japanese culture and spirituality since its start. Sake’s religious significance even now remains well documented, with stacked rows of sake barrels and bottles displayed prominently at Shinto shrines. 

While the basic brewing techniques remain consistent, each sake brewery across Japan infuses its own unique characteristics:

• Kanazawa Junmai Sake Specialists: This Ishikawa Prefecture-based sake brewery specializes in junmai sake, a type of sake that contains no additive ingredients, keeping the flavor pristine and balanced. Founded in 1625, the brewery uses mineral-rich water that flows from nearby Mt. Hakusan that’s filtered slowly underground for 100 years before reaching the wells of the brewery.

• Osaka Sake Brewery Tour: At this internationally acclaimed brewery, operated by a 6th-generation sake master on the outskirts of Osaka, an immersive tour brings visitors right to the heart of production. Following in-depth explanations of the koji cultivation process and sake brewing methods, guests can sample a range of sake while learning the nuances of sake's multidimensional flavors.

• Tokyo Sake & Otsumami Pairing: An immersive instruction into the pairing between sake and food, this Tokyo-based experience further explores the role fermented food plays in Japanese cuisine. When combined together, sake can be used to complement the notes of the dish, enhance the natural flavors of the food, and serve as a palate refresher between plates.

Shottsuru Fish Sauce:

Shottsuru, a fish sauce seasoning packed with intricate flavors, requires only salt and fish for its production. Historically, this hyperlocal specialty was crafted from fresh catches along Japan's vast coastline, undergoing a fermentation process lasting up to 2, and often, 3 years. Today, Akita Prefecture stands as one of the few regions preserving this culinary tradition, with shottsuru breweries like this one operating since the Meiji period to safeguard the legacy of this fermented seasoning. A versatile condiment with a nutty aroma, shottsuru is essential in traditional dishes like hatahata nabe and can enhance pasta, soup, chahan rice, and more.

• Shottsuru Factory Tour: Witness the meticulous fermentation process firsthand at this renowned Akita shottsuru brewery and discover the complex flavors after, with a culinary adventure centered around the taste of this unique sauce.

Tsukemono:

Pickled food in Japan, or tsukemono, comes in a diverse variety of flavors and appearances - from thinly slicked, salt-soaked cucumbers to vivid gold radish cut into half-circle shapes. Tsukemono are traditionally eaten at the end of a meal and are thought to aid in digestion and promote gut health. The simplest method of fermentation is achieved by adding salt to raw materials, but many other kinds of marinated tsukemono exist, resulting in a greater range of fermented products. 

One well-renowned example of tsukemono developed in the 17th century, nukazuke, is made by fermenting vegetables in nuka (rice bran). A complex and time-intensive process, the nuka must first be developed in a crock using a mix of water, salt, and seaweed, although additional ingredients like ginger, garlic, or even beer can also be added to enhance the flavor. Then, the fresh produce or fish must be carefully covered and monitored for up to a month in this pickling process.

• Gastronomy of Koji Workshop: A fermented food masterclass in Kanazawa, guests learn the secrets of using koji to craft tsukemono pickles directly from a brewery with over 150 years of pickle-producing history, famous for their kabura-zushi and daikon-zushi.

Japanese Culture & The Fermented Culinary Scene

While early fermentation might have been a stroke of luck, occurring naturally due to environmental conditions, modern fermentation processes are as much an art as they are a science, carefully controlled by professional brewers who dedicate their lives to this culinary craft. From toji head brewers who meticulously observe the production of sake to the patient preservation efforts of tanekoji-ya to sustain koji cultures, Japan’s revolutionary fermented foods have always been a combination of the efforts of skilled culinary craftspeople and the raw power of microorganisms. 

The savory tang of fermented ingredients and seasonings provides a rich and complex depth to Japanese cuisine, which balances the simplicity that defines the nation’s staples – the refined, pristine taste of sashimi elevated with a small splash of soy, the foundation of every teishoku meal cemented by the wafting scent and warm steam of miso soup, and even the multifarious pairing of sake to round out a late-night meal. Yet, fermented food has often been left the unsung heroes of Japanese cuisine, providing the depth of flavor without receiving widespread recognition. 

Currently, however, an explosion of interest has led to exciting innovations in fermented food culture; international and domestic trends are appreciating not just the complexity in taste and health benefits of fermented food as a whole, but more specifically, the unique culture of fermented cuisine within Japan. Moreover, new applications of traditional fermentation methods have grown faster than koji spores in warm climates, spreading out across time zones and borders to add a dash of exciting Japanese flavor to the culinary scene. 

Other national staples include natto, a tangy, slippery superfood made from fermented soybean that remains polarizing in Japan due to its distinctive smell, and mirin, a syrupy sweet cooking alcohol that urges out an umami taste from food when used in cooking. Beyond the foundational fermented culinary options seen widespread across the country, there are also countless regional delicacies cultivated using microorganisms, from Okinawan fermented bean curd to fish pickled in rice bran, or even kanzuri, a fermented chili paste.

Whether through guided sake brewery tours or miso factory and fine-dining pairings, understanding the culture of fermentation in Japan is essential to understanding the very foundation of Japanese food itself. An increased awareness of the complex - and varied - fermented flavors that enrich Japanese cuisine not only enhances understanding of Japan’s culinary arts, but also provides insight into Japanese culture and historical practices.

Discover the rich, savory heritage of fermented food in Japan, where every bite is a gastronomical journey waiting to begin.

About the Author: A creative writer and Japanese Literature and Culture scholar, Taylor Bond focuses her academic research on cultural formation, folklore, and East Asian comparative culture. Her creative work includes both prose and poetic content, often exploring themes of the self and lyrical surrealism.

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