The Science of Starter-Making: Bodaimoto, Kimoto, Yamahai, and Sokujo

Moto-zukuri, or starter-making, is an essential step in the sake brewing process. The starter (moto/shubo) cultivates lactic acid, sterilizing the yeast and protecting it from dangerous microbes. Methods of starter-making have evolved over time as the science behind the process became understood.

Bodaimoto

The first documented method of lactic acid cultivation is the bodaimoto method, named in honor of the Buddhist temples where it originated. Buddhist monks would place steamed rice in bamboo baskets, soak the baskets in water for three days, then use the water and rice in the next stage of sake brewing. Even though the science behind this method was not yet understood, brewers knew it was a necessary step and the bodaimoto method spread to sake breweries beyond temples.

Kimoto

During the Edo period, beginning in the 1600s, the kimoto method became the new standard. Kimoto involves a labor-intensive process called yama-oroshi. Every two hours for an entire day, paddles called kai are used to grind and mix together steamed rice and koji rice.

Brewers have found that kimoto sake is better for maturing than sake made with other starter methods. Kimoto sake also tends to have rich layers of flavor and a lingering aroma. For these reasons, some sake breweries still choose to use the kimoto method despite more efficient, modern methods being available.

Yamahai

In 1909, government funding allowed researchers to study the science behind sake. They discovered that lactic acid was the secret ingredient protecting the yeast. They also discovered that the labor-intensive mixing required by the kimoto method was not necessary to maintain the yeast’s quality. Omitting this step led to the yamahai method.

The bodaimoto, kimoto, and yamahai methods all use naturally occurring lactobacillus bacteria from the air to propogate lactic acid.

Sokujo

Shortly after the yamahai method was developed, the sokujo method was introduced. Instead of cultivating lactobacillus, pure lactic acid is added to the moto. The sokujo method increased the efficiency of starter-making, causing it to spread in popularity and become the main method used in sake production today.

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