What is Shubo? A Complete Guide to Sake Making

Author: Joost Nusselder, author of The Essential Japanese meal planner cookbook Updated September 30, 2022

What is shubo?

Shubo is a type of rice used to make sake. It’s a very delicate process that requires a lot of work and attention to detail. It’s a foundation of sake making.

I’ll take you through the process and explain everything you need to know.

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The Role of Shubo in Sake Production

Shubo, also known as moto or mother, is a critical stage in the sake-making process. It is a yeast starter that is produced by adding steamed rice, water, and kobo (yeast) to a mixture of lactic acid bacteria and yamaoroshi (a traditional tool used to break up clumps of rice). Shubo is the foundation of the sake-making process and plays an essential role in creating the unique taste, aroma, and acidity of sake.

How is Shubo Produced?

The production of shubo is a delicate and time-consuming process that requires a lot of work and attention to detail. Here’s how it’s done:

• First, the rice needs to be milled to remove the outer layers, leaving only the starchy core. The degree of milling depends on the type of sake being produced, with higher quality sake requiring more milling.
• Next, the rice is steamed to make it soft and pliable, making it easier for the microorganisms to grow.
• Once the rice has cooled down, it is mixed with water and kobo to create a mash.
• Lactic acid bacteria are then added to the mash to create an environment that is ideal for the growth of microorganisms.
• The mixture is then left to ferment for approximately two weeks, during which time the yeast and bacteria grow and multiply, turning the mash into a thick, frothy liquid.
• The shubo is then ready to be used in the next stage of the sake-making process.

The Importance of Shubo in Sake Making

Shubo plays a critical role in the sake-making process for several reasons:

• It helps to create the unique taste, aroma, and acidity of sake by facilitating the growth of microorganisms that produce these characteristics.
• It protects the sake from harmful bacteria and other microorganisms that could spoil the taste and quality of the final product.
• It allows for the uniform growth of microorganisms, creating a consistent and high-quality product.
• It helps to prevent the mash from going sour by creating an environment that is ideal for the growth of microorganisms that produce lactic acid.

The Different Types of Shubo

There are several different types of shubo, each with its own method of production and resulting taste and quality:

• Sokujo-kei shubo: This is a quick-fermenting yeast starter that is produced by adding lactic acid and yeast to the mash at the same time. It is the most common type of shubo used in modern sake production.
• Kimoto-kei shubo: This is a traditional method of producing shubo that involves creating a mash by adding water, rice, and kobo, and then using a yamaoroshi to break up the clumps of rice. This method takes longer than sokujo-kei shubo but results in a more complex and flavorful sake.
• Yamahai shubo: This is a method of producing shubo that involves allowing the mash to undergo a natural fermentation process without adding lactic acid. This method results in an extremely strong and powerful sake with a rich aroma and acidity.

The Role of Shubo in Facilitating Saccharification

Shubo also plays a fundamental role in facilitating saccharification, the process by which the starch in the rice is converted into sugar. This is done by adding koji, a type of mold that breaks down the starch in the rice, to the shubo. The resulting liquid is then added to the mash, where the sugar is converted into alcohol.

The Importance of Maintaining the Shubo

Maintaining the shubo is essential for producing high-quality sake. Here are some of the things that need to be done to maintain the shubo:

• The shubo needs to be stirred regularly to prevent the growth of harmful bacteria and ensure that the microorganisms are growing uniformly.
• The temperature and humidity of the environment need to be carefully controlled to ensure that the microorganisms are growing at the optimal rate.
• The shubo needs to be protected from contamination by other microorganisms that could spoil the taste and quality of the final product.

The Differences Between Shubo and Yeast

While yeast is an essential ingredient in sake production, it is not the same as shubo. Here are some of the differences between the two:

• Shubo is a mixture of yeast, lactic acid bacteria, and other microorganisms, while yeast is a single type of microorganism.
• Shubo is used to create an environment that is ideal for the growth of microorganisms, while yeast is added directly to the mash to convert sugar into alcohol.
• Shubo plays a critical role in creating the unique taste, aroma, and acidity of sake, while yeast primarily contributes to the alcohol content.

The Importance of Shubo in Sake Making

The microorganisms in shubo play a fundamental role in facilitating the growth of yeast and creating the ideal environment for it to thrive. The lactic acid bacteria help to increase the acidity of the mixture, which helps to prevent the growth of unwanted bacteria. The yeast turns the sugars in the rice into alcohol, and the resulting liquid is used to create sake.

The Importance of Time in Shubo Production

The shubo stage takes approximately two weeks to complete, and during this time, the mixture needs to be carefully monitored and maintained. The longer the shubo is allowed to ferment, the more uniform the resulting liquid will be.

The Resulting Taste and Aroma of Sake

The taste and aroma of sake are directly influenced by the shubo. The acidity of the mixture helps to bring out the delicate flavors of the rice, while the yeast creates the alcohol content and aroma. The type of shubo used can also result in different flavor profiles, depending on the method of production and the microorganisms used.

Shubo: The Cornerstone of Sake Making

Shubo, also known as moto, is the yeast starter that plays an extremely important role in creating the delicate and strong flavors of sake. It is the base of the fermentation process and determines the final taste of the sake. The purpose of shubo is to produce a large amount of lactic acid and yeast to protect the sake from bacteria and other microorganisms that could harm the fermentation process.

How does shubo work?

Shubo is created by steaming rice and mixing it with water and a type of mold called kobo. There are two types of shubo: sokujo-kei and kimoto-kei. The type of shubo used determines the flavor and character of the sake. Once the shubo is created, it turns into an acidic environment that is weak in resistance to bacteria. This is where the yeast performs its role by growing and multiplying to produce alcohol.

Why is shubo given such importance in sake making?

Shubo is considered the cornerstone of sake making because it determines the final taste of the sake. The delicate balance of the shubo determines the strength and flavor of the sake. The characters of the shubo are sourced from the water used, the type of rice used, and the type of mold used. The editorial team of sake makers must learn how to create the perfect shubo to produce the best sake.

How does shubo protect the sake from harmful microorganisms?

Shubo produces a large amount of lactic acid and yeast that protect the sake from bacteria and other microorganisms that could harm the fermentation process. The acidity of the shubo creates an environment that is not suitable for harmful microorganisms to grow and thrive. The yeast in the shubo performs the role of producing alcohol, which also protects the sake from harmful microorganisms.

What is the difference between a strong and delicate shubo?

The difference between a strong and delicate shubo lies in the type of mold used and the way it is produced. A strong shubo is produced using the sokujo-kei method, which is a quick fermenting yeast starter. This type of shubo produces a strong and clean flavor. A delicate shubo is produced using the kimoto-kei method, which is a traditional method of creating shubo. This type of shubo produces a delicate and complex flavor.

What is the meaning of shubo in Chinese characters?

Shubo is written in Chinese characters as 酒母. The first character 酒 means “sake” and the second character 母 means “mother”. This reflects the importance of shubo in sake making as the “mother” of the fermentation process.

The Quick and Easy Sokujo-kei Shubo Method

The Sokujo-kei shubo method consists of the following steps:

• Rice is steamed and placed in a large container.
• Water and a small amount of lactic acid are added to the rice.
• The mixture is stirred to ensure that the rice is completely wet.
• Yeast and koji are added directly to the mixture.
• The mixture is stirred again to make sure that everything is mixed well.
• The mixture is then left to rest for a day.

What Happens During the Sokujo-kei Shubo Process?

During the Sokujo-kei shubo process, the following stages occur:

• The mash goes through a saccharification period, where the starch in the rice is converted into sugar.
• The yeast starts to ferment the sugar, which produces alcohol.
• The temperature of the mash is kept at a high level, around 15-20 degrees Celsius, to prevent unwanted bacteria from growing.
• The mash is stirred regularly to maintain a consistent temperature and to prevent the yeast from settling at the bottom of the container.
• The Sokujo-kei shubo method takes a short period of time, usually around 5-7 days, compared to the Kimoto-kei shubo method, which can take up to 30 days.

What Makes Sokujo-kei Shubo a Prominent Technique in Sake Production?

Sokujo-kei shubo offers a few advantages over the Kimoto-kei shubo method:

• The Sokujo-kei shubo method is easy and simple to carry out.
• The Sokujo-kei shubo method uses a pure yeast starter, which offers a little influence on the final flavor of the sake.
• The Sokujo-kei shubo method produces a consistent quality of sake.

What is the Key to Making Good Sake Using Sokujo-kei Shubo?

The key to making good sake using the Sokujo-kei shubo method is to maintain a high level of cleanliness and to make sure that the temperature of the mash is kept at a consistent level.

What is the Result of Using the Sokujo-kei Shubo Method?

The result of using the Sokujo-kei shubo method is a sake that has a clean and crisp taste, with a little acidity and a prominent aroma.

What is the Ideal Temperature for Sokujo-kei Shubo?

The ideal temperature for the Sokujo-kei shubo method is around 15-20 degrees Celsius. This temperature is high enough to prevent unwanted bacteria from growing, but low enough to prevent the yeast from becoming too active and producing unwanted flavors.

Kimoto-kei shubo- The Traditional and Complex Yeast Starter

Kimoto-kei shubo is a traditional method of creating a yeast starter in the production of sake. It is a complex and time-consuming process that involves a series of stages to achieve the desired result. The method is known for producing a unique character in sake that is different from other types of yeast starters.

What are the benefits of using Kimoto-kei shubo?

Kimoto-kei shubo is a popular alternative to the quick fermenting yeast starter, Sokujo-kei shubo. The benefits of using Kimoto-kei shubo include:

• Producing a complex and unique character in sake that is difficult to achieve with other yeast starters.
• Allowing for a more natural and traditional method of sake production.
• Building a lot of nitrous and lactic acid concentration in the cells of the yeast starter, which helps prevent unwanted bacteria from producing.

Why is Kimoto-kei shubo important in the world of sake production?

Kimoto-kei shubo is an important part of the world of sake production because it represents a traditional and complex method of creating a yeast starter. It allows for the production of unique and complex sake varieties that cannot be achieved with other yeast starters. While it may be a difficult and time-consuming process, the resulting sake is often considered to be of a higher quality and is sought after by those looking for a more traditional and authentic sake experience.

Conclusion

So, that’s shubo! It’s a critical stage of sake making and it’s a delicate process that requires a lot of work and attention to detail. 

It’s important to maintain the shubo and protect it from contamination, so you can produce a high quality final product. So, don’t be afraid to give it a try!

Check out our new cookbook

Bitemybun's family recipes with complete meal planner and recipe guide.

Try it out for free with Kindle Unlimited:

Read for free

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.