What is moromi? The essential fermentation starter for sake and soy sauce

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Sake is a beloved Japanese rice-based alcoholic drink, and soy sauce is a common seasoning in many Asian foods.

Fermented rice or soy products are extremely popular in Japan. But to make fermented foods and drinks, a thick brown liquid is used.

Moromi is a necessary “base product” used in the manufacturing process. It is also known as saké lees or saké kasu in Japanese and sake mash in English.

What is moromi? The essential fermentation starter for sake and soy sauce

Moromi is known as “sake mash” in English. It is sake mash, a primary fermentation mixture made by mashing steamed rice, koji, shubo (yeast), and water. It’s a soft, viscous rice mound full of liquid that is then filtered and used to produce a Japanese fermented rice drink called sake.

Moromi is made by combining steamed rice, koji, yeast, and water. The mixture is then fermented for a period of time, typically two weeks.

During this time, the yeast and koji break down the carbohydrates in the rice into alcohol and carbon dioxide.

After fermentation is complete, the moromi is then pressed to remove the solid particles, resulting in sake or soy sauce.

In this post, I will talk you through what moromi is, how it’s used, and why it’s such an essential starter ingredient in some of Japan’s most popular fermented foods and drinks.

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What is Moromi?

Moromi is a key ingredient in the making of sake and soy sauce, and its quality greatly affects the final product.

Moromi is sometimes also called moromi-miso, although it has nothing to do with miso paste.

It is a viscous liquid with the texture of honey or thick molasses and is made by mashing steamed rice, koji (a fermented rice product), shubo (yeast), and water.

Soybeans are often used instead of rice to make soy sauce – it can also be called moromi.

It’s known as “sake mash,” and initially, it looks like a large mass of puffy rice.

It undergoes the saccharification process, during which carbohydrates are broken down into alcohol and carbon dioxide by the yeast and koji.

Initially, the moromi is a big lump of fermenting rice, and during the breakdown, it becomes more fluid.

As it gets soft and starts to flow, the Japanese say the moromi “turned.” In Japanese, it’s called moromi ga kaetta, 醪が返った.

Even after a certain amount of liquefaction, the initial specific gravity, viscosity, and sweetness of the mash are incredibly high.

As fermentation continues, specific gravity decreases, and the mash gradually becomes lighter (more liquid) and less sweet – that’s when they know it has turned and is ready to be filtered.

Before mashing, the moromi is called moromi-zake or doburoku.

Think of moromi as a starter ingredient in the fermented food and drink manufacturing process.

After fermentation is complete, the moromi is then pressed to remove the solids, resulting in a clear liquid that is either sake or soy sauce.

It is possible to estimate the fermentation stage based on changes in sugar content (sweetness) and specific gravity.

In later stages of the fermentation process, the specific gravity approaches or even falls below that of water, and the viscosity of the liquid portion approaches that of water.

Alcohol supplants sweetness with a dry taste.

When the solid and liquid are separated, the process is called joso, and there are several ways to do it.

Mature moromi is pressed to give seishu and sake kasu (compressed sake cake).

So, moromi is an essential ingredient in two of Japan’s most popular fermented foods: sake and the savory soy sauce used for cooking.

For this reason, brewers take great care in ensuring that the moromi is of the highest quality.

Types of moromi

There are two main types of moromi:

Sake moromi

Also called doburoku, this refers to the thick liquid that results from the fermented rice, shubo, koji, and water mixture.

The highly viscous mixture is then filtered, and this is what we know as raw sake. Before the drinking sake is ready for consumption, the raw sake is refined and processed.

However, there is “doburoku,” a commercial product without sake moromi filtration – it’s basically unfiltered sake.

According to the Japanese Liquor Tax Law, Japanese sake is referred to as “refined sake,” and it is mandatory to filter the sake moromi.

In Japan, “doburoku” is therefore not classified as “refined sake” but as “other brewed liquor.”

When you taste doburoku, you will detect the incredible sweetness of the rice, moderate acidity, and exquisite aroma.

Because the ingredients are not filtered, it is also very nutritious.

Soy sauce moromi

Also called shoyu no mi or “fruit of soy sauce,” this is the thick mixture that results from fermenting soybeans, wheat, salt, and water.

The mixture is then filtered, and this is what we know as soy sauce.

As with sake, the soy sauce moromi goes through a fermentation process, but instead of rice, soybeans are used to make the moromi.

In some regions of Japan, such as the Yamagata, Niigata, and Nagano prefectures, soy sauce moromi is consumed on its own or as a substitute for seasonings.

It can even be used as a savory seasoning.

In addition to tasting the flavor and umami of soy sauce, you can also detect the texture of soybeans and wheat.

Other types of shoyu moromi are made by adding sugar or other substances to the traditional soy sauce ingredients of soybeans, wheat (or barley), koji, and salt.

Consequently, there are variations in flavor, ranging from intensely sweet to intensely salty, depending on the ingredients.

You can top “shoyu no mi” with grilled fish, meat, cold tofu, shredded daikon, etc. It complements any dish, as well as soy sauce.

What does moromi taste like?

Moromi has a sweet and sour taste with a slightly alcoholic smell.

The taste and smell of moromi will change as it ferments, and the final taste will depend on what the moromi is used to make.

If it is used to make soy sauce, it will have a salty and savory taste, while if it is used to make sake, it will have a sweet taste.

How is moromi made?

Sake moromi is made by fermenting rice, koji, shubo, and water.

The rice is first steamed, and then the koji, shubo, and water are added to it.

The mixture is then left to ferment for around two weeks.

Soy sauce moromi is made by fermenting soybeans, wheat, salt, and water.

The soybeans and wheat are first steamed, and then the salt and water are added to them.

The mixture is then left to ferment for around three months.

How is moromi used?

Moromi can be used to make sake and soy sauce as well as other fermented foods and drinks.

To make sake, the moromi is filtered and the resulting liquid is refined and processed.

To make soy sauce, the moromi is filtered and the resulting liquid is fermented.

Moromi can also be used to make other fermented foods such as miso and rice vinegar.

Since moromi is a general fermented base, it is quite versatile and not limited to making sake.

What is the role of Moromi fermentation?

The role of fermentation is to change the structure of carbohydrates, proteins, and fats so that they can be easily digested by the body.

But the actual role of the moromi is to ferment.

Thus, the protease and amylase from fungus hydrolyze the proteins and polysaccharides, and this creates various nitrogen compounds as well as sugars and amino acids.

What’s the origin of moromi?

The word moromi comes from the verb moru, which in old Japanese meant “to accumulate.”

The character for mo (母) can also be read as haha, which means “mother.” So moromi can literally be translated as “mother liquor” or “mother of fermentation.”

This name was given because moromi is the key ingredient in the manufacturing process of both sake and soy sauce.

Prior to pressing, the mash was known as doburoku or moromi-zake, and was not only produced in sake breweries but also consumed by farmers and commoners.

With the establishment of the Liquor Tax Law during the Meiji Era, however, home brewing became illegal during the years 1868-1911.

Fermented rice food and drinks were invented in China more than 2500 years ago.

But moromi has a long history in Japanese culture and is mentioned in the Manyoshu, an eighth-century anthology of Japanese poetry.

One poem, in particular, praises the doburoku of Mt. Miwa, and it is thought to be the oldest poem that mentions this drink.

The Manyoshu also contains a poem that mentions kasutori shochu, which is made by distilling moromi.

For as long as soy sauce and sake have been around, moromi has been the key mixture to making them.

What are the benefits of moromi?

Moromi is rich in vitamins and minerals, and it also contains enzymes that help with digestion.

It is a good source of protein, and it also contains koji, which is known to have many health benefits.

Some of the health benefits of koji include:

  • Boosting the immune system
  • Improving digestion
  • Reducing inflammation
  • Enhancing liver function

Moromi is also a good source of probiotics, which are beneficial for gut health. In fact, moromi is part of a category of healthy fermented foods and drinks known as kampocha.

Kampocha includes other fermented foods and drinks such as kimchi, sauerkraut, kefir, and kombucha.

These foods and drinks are all rich in probiotics and have many health benefits for the digestive system, and are considered to be medicinal foods.

Moromi vs Moromi miso

The flavor of moromi miso is similar to that of sweet miso with a grainy texture, but it is not actually miso paste.

It’s a common misconception to mistake miso paste and moromi, however, they’re not the same.

Even some Japanese individuals erroneously believe that moromi miso is the product of the miso-making process. That is false.

Moromi miso refers to the food that is similar to soy sauce moromi and is created for consumption from the outset. It can be used as a condiment.

Moromi miso can be made using the same method as soy sauce. In this case, it is distinguished by a reduction in the salt content of the used salt water.

On the other hand, it is sometimes made with soy sauce, koji, amazake, sugar, and sesame that are commercially available. There are numerous preparation methods and varieties.

Others consider “shoyu no mi” to be moromi miso, whereas some make relatively sweet moromi miso with sugar or crystal sugar.

What is moromi natto?

Moromi natto is a variety of natto (fermented barley) that is made using moromi. Basically, it’s barley inoculated with koji mold.

The moromi used is typically a leftover ingredient from making soy sauce or miso.

The natto is made by mixing the moromi with whole soybeans and allowing them to ferment.

The resulting product is a sticky, viscous food that is high in protein and rich in flavor.

Unlike the moromi used to make sake and soy sauce which is not eaten, moromi natto is a popular dish that is often eaten as a side dish or for breakfast.

It can be served with rice, on top of noodles, or used as a supplement.

Learn how natto differs from miso in taste and production process here

Where to buy moromi

Moromi is not the type of ingredient to buy at the grocery store.

Since it’s a base ingredient for fermented foods and drinks, it’s typically made by fermented food and drink manufacturers.

Some companies that make moromi include:

  • Yamasa Corporation
  • Kikkoman Corporation
  • Marukome Co., Ltd.

There are some brands in Japan that carry packaged moromi masses people can use to make sake and other products at home.

If you’re interested in making your own fermented foods and drinks, it’s best to make your own moromi.


Moromi is a key ingredient in many fermented foods and drinks, such as sake, soy sauce, and miso. It’s also known as “sake mass” because of its lumpy shape.

Moromi is rich in vitamins, minerals, enzymes, and probiotics, so it’s part of what makes fermented food and drinks healthy.

Japanese cuisine has a long history of fermentation, and moromi has been used for centuries to make traditional foods and drinks like their national drink sake.

Next, find out some amazing recipes that you can make using sake

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Joost Nusselder, the founder of Bite My Bun is a content marketer, dad and loves trying out new food with Japanese food at the heart of his passion, and together with his team he's been creating in-depth blog articles since 2016 to help loyal readers with recipes and cooking tips.