In 2013, traditional Japanese cuisine was registered on UNESCO’s Lists of Intangible Cultural Heritage. The booming popularity of Japanese food in recent years has helped it spread across Australia and all throughout the world. Moreover, a World Health Organization (WHO) report found that of its 194 Member States, Japan led the world in terms of average life expectancy in 2016 at an average age of 83.7 for men and women, leading to further praise for the healthy nature of Japanese food and driving the spread of Japanese restaurants and supermarkets offering Japanese ingredients across Australia. Its popularity is such that numerous words from the culinary vocabulary of Japan such as umami, dashi, sake, and the names of other ingredients are recognised in the English language. To find what forms the very backbone of this culinary culture, you need look no further than fermented foods.




Fermented food refers to food products that are created by intentionally adding microorganisms such as bacteria, mould, or yeast to wheat, legumes and other foodstuffs to break them down. While the products of the fermentation process largely depend on the exact combination of base ingredients and the microorganisms involved, the alcohol and organic acids increase the intensity of the flavour. Some fermented foods also aid in digestion and are high in nutritional value.

Fermentation itself is a process where the rapid multiplication of these microorganisms is used to change the original composition of ingredients in a way that is beneficial to human beings. Enzymes naturally found in the bacteria in food ingredients break down starches and proteins to create amino acids, sugar, and a variety of other products, creating a new flavour and full aroma not found in the original ingredients and changing them into a fermented food high in nutritional value. It should also be noted that when the action of bacteria is beneficial to the human body, it is known as “fermentation”, and when it is detrimental, it is known as
“decay”. By the same token, bacteria that cause a fermentation reaction in foods are called “good bacteria”, while those that cause food to decay are called “harmful bacteria”.

Japan itself is one of the top producers of fermented food products in the world. In particular, fermented foods created using koji mould are said to have been a key factor in the development of Japan’s fermented food culture. Yet while the benefits of fermented foods have been gaining increased attention in recent years, many are still unfamiliar with the exact mechanism by which fermentation works and how it creates such full flavour.


Fermented food products have appeared in countries across the globe as a form of preserved food since the times of old. Where the main varieties in the West were bread, yoghurt, cheese, salami, anchovies, beer, and wine, in the East, outside Japan, were kimchi, fish sauce, and fermented tofu. Some of the more common varieties of fermented foods in Japan include soy sauce, miso, vinegar, mirin, natto, katsuobushi, pickled vegetables, sake, shochu, and more.

Soy sauce is made through a fermentation of soybeans and wheat using koji mould, yeast, and lactic-acid bacilli. The fermentation process increases the level of amino acids present, which boosts the umami flavour and imparts the sweetness of grape sugar, the acidity of lactic acid, and the bitterness of peptides that come together to produce the unique flavour of soy sauce. The key principles of cooking in Japan are said to be the amount of salt used, the dashi, and the level of heat applied, all of which are influenced by soy sauce. Soy sauce is the deciding factor in the level of salt in a dish, and also contains glutamic acid, which is a component of dashi. The smell of soy sauce caramelising is one that whets the appetite and is a moment where chefs can showcase their cooking skills. This distinct aroma is one that only soy sauce can produce. To the Japanese, soy sauce is so broad in its application that it is hard to find a dish with which it would not pair well. Its colour, flavour, and aroma partners well with and complements meat, fish, vegetables, and all ingredients without being overly pronounced.


Soy sauce is so natural a complement to sushi and sashimi that it is hard to imagine them without it, but there is a reason why it makes such a good match. While it does, of course, add to the flavour, soy sauce also has the ability to cancel out the raw smell of the fish. It is also mildly acidic in nature, and neutralises the trimethylamine that is the root cause of this smell. Soy sauce is also sterilising. There are also reports that the salt, alcohols, and organic acids halt the growth of and kill bacteria in the gut.

Miso, a staple of the Japanese dining table, is known as the “meat of the fields” for the high level of protein it contains, and is made by fermenting soybeans to bring out a sweetness and umami and make it easier to consume. It warms the body, promotes good circulation and gut health, fights cancer, slows the effects of ageing, lowers cholesterol, and provides a range of other benefits. The health benefits of the high nutritional value it offers have even earned it the phrase “eat miso and say goodbye to the doctor”. There are many types of miso such as rice miso, barley miso, and soybean miso each differentiated by their production methods and ingredients, and red, light yellow, and white miso based on colour.



In much the same way as there is a wide variety of fermented foods in the world, there is an equally wide variety of the bacteria used to create it. Let’s take a look at the five main types.

A type of mould that multiplies when heat is applied to cereals such as rice and soybeans. Two types of enzymes produce sugars and amino acids during the fermentation process, adding sweetness and umami to the flavour. Essential to the creation of miso and soy sauce.

A fungus that breaks down sugars to produce carbon dioxide and alcohol. Found everywhere from the air and in the ground to the surface of vegetables. Used to create alcoholic drinks, bread, miso, soy sauce, and more.

The collective name for a type of fungus that converts alcohol into acetic acid. Vinegar is alcohol
passed through an acetic acid fermentation. From rice vinegar made from sake to wine vinegar made from wine, there are as many types of vinegar as there are types of alcohol.

A fungus that breaks down sugars to create lactic acid. Yoghurt and cheese are products of a lactic fermentation. Also involved in the process of creating miso, soy sauce, and sake. Highly acidic in nature, it is also able to kill other types of bacteria.

A bacteria found on rice stalks. Creates natto when natto bacteria is added to steamed soybean. Natto bacteria produces a special type of enzyme called, “nattokinase” that is good for gut health and promotes good blood flow.


Condiments such as soy sauce and miso that form a core component of Japanese food would not be possible if not for koji, and it is no exaggeration to say that Japan’s unique culinary culture owes its existence to the powers of the koji that shaped it. Koji is a product of koji mould being applied to steamed cereals such as rice, wheat, and soybean and allowed to reproduce under the right heat and humidity.


Based on the principles of macrobiotics, fermented foods are a core foodstuff that should be proactively incorporated into one’s daily diet. They are both traditional in nature, and represent a tradition of techniques used to preserve local seasonal produce. Fermented foods also contain live bacteria known as probiotics that are beneficial to the human body.

Consuming fermented food products, which are probiotics, adjusts the balance of intestinal flora and promotes good gut health. They offer many benefits, playing a role in invigorating enteric bacteria, promoting good passage, and leading to larger numbers of good bacteria in the gut. Probiotics are also good for our mental wellbeing.

It was recently scientifically proven that certain bacteria have the psychological benefit of reducing feelings of unease in the internal organs, and the bacteria commonly used in fermented foods common to Japanese cuisine are said to reduce anxiety and stress, and boost your sense of happiness.




When bacteria come in contact with the base ingredients of food, they use enzymes to convert starches into a sweet component – sugar – and proteins into an umami component – amino acids. This gives fermented foods their well-rounded, deep flavour and softness, increases their nutrient makeup, and boosts their level of umami flavour. The enzymes produced by the bacteria have a great effect on the flavour and aroma of the food.


The benefits of fermentation are not just in altering the flavour, aroma, and makeup of food. Fermented foods can often also be preserved over a long period of time, many of which were originally created with this quality in mind. For example, miso and natto last longer than soybeans, and cheese and yoghurt last longer than milk. One contributing factor to this is that fermented foods are often prepared using salt, but the main reason is that the bacteria that bring about fermentation prevent the multiplication of other bacteria. The good bacteria contained in fermented food counter bad bacteria that cause decay, and the components created during the fermentation process themselves sometimes have antibacterial capabilities, making them a powerful preservative. This action has the ability to halt the decaying effects of bad bacteria to an extent, allow in foods to be preserved longer than in their fresh state and also increasing the umami flavour by maturing the food.


Fermentation accelerates the process of decomposition, leaving food in a state where it is easier to take in the nutrients in comparison to other food, and making it perfect for receiving an immediate intake of nutrients. The enzymes and lactic-acid bacilli found
in fermented foods also promote gut health and strengthen immunity. They contain a large amount of good bacteria that promote good gut health and boost immunity, and the increase in good bacteria in the gut lowers the level of bad bacteria, boosting immunity by allowing you to take in more nutrients; not to mention the antioxidants such as vitamin C, carotene, flavonoids, polyphenol and more, all of which fermentation makes easier to take into the body, removing free radicals (reactive oxygen) and increasing the efficiency of amino acid and enzyme intake required for beautiful skin, providing an anti-ageing effect. The enzymes included in fermented foods promote good digestion and make it easier to pass decayed enzymes that act as food for bad bacteria. The lactic-acid bacilli included in many fermented foods also promote good gut health and have a detoxing effect.

Incorporating fermented Japanese foods into your diet will help both your body and mind stay happy and healthy.



Fermented foods have appeared across the world through the ages. Their history is a long one, and while it is unclear when they first came about exactly, estimates place it at 4,000 to 6,000 years ago. In other words, fermented foods have been loved by people across the world since before the times of recorded history.

The oldest written record in Japan is of salt-pickled gourd described on a wooden tablet during the Tenpyo era (729 – 749) of the Nara period. Japan’s warm, humid climate is well suited to fermentation, and fermented foods made using koji created by steaming rice, wheat, and soybeans have been common throughout the ages. The creation of koji mould was a key element in enabling the creation of various fermented food products that are pillars of Japan’s culinary culture such as soy sauce, miso, sake, and vinegar.

There were already makers of seed malt used in the production of koji in the Heian period, thought to be the first commercial traders in bacteria across the world. There was even a soy sauce producer in Kyoto around that time that could make soy sauce based on four types of base ingredients (cereals, fish, meat, and vegetables) using an incredible technique where ash was used to extract koji mould and nothing else.