Hello, I’m Mana. This time, I want to share about the manufacturing process of sake, which I’ve learned through studying for the Sake Certification. Isn’t it fascinating how sake, made from just rice and water, can have such a complex flavor? The answer lies in the intricate production process of brewing sake. Let’s take a look at the overall flow today.
1. Rice Milling – Preparing the Foundation of Flavor
The rice used for sake, different from ordinary eating rice, is called “sakamai,” or sake brewing rice. However, this rice isn’t used as it is; first, it undergoes “rice milling.” Rice milling involves shaving off the outer layers of the rice grains, which contain proteins and fats. This important step removes impurities that could affect the taste of the sake.
The degree of rice milling is indicated by the “seimai-buai” or rice milling ratio. For example, a 60% seimai-buai means that 40% of the rice has been milled away. The lower the milling ratio (i.e., the more the rice is milled), the more delicate and fruity the sake tends to be. On the other hand, less milling preserves the robust umami flavor inherent in the rice, producing a sake with a strong rice flavor.
Since the milled rice generates heat, it is cooled down in a process called “korashi,” allowing the rice to rest after milling. This is another crucial step in creating delicious sake.
2. Koji Making – Transforming Rice into Sugar with Koji Mold
Next comes “koji,” an essential microorganism in sake production. Steamed rice is sprinkled with koji mold to start the “koji making” process. The role of koji mold is to convert the rice’s starch into sugar, a process called “saccharification.” Without this conversion, alcohol fermentation cannot proceed, making koji a crucial component.
There are various types of koji mold, but the one most commonly used in sake is “yellow koji mold.” The mold is carefully managed to spread evenly across the steamed rice over about two days of fermentation. During this time, the rice is mixed repeatedly in a process called “kirikaeshi.” This ensures the starch is converted to sugar, setting the stage for the next fermentation process.
The final texture of koji can be either “so-haku-sei” (where the koji mold permeates thoroughly, resulting in complete saccharification and a rich flavor) or “tsuki-haku-sei” (where the mold spreads mainly on the surface of the rice grains, leading to a lighter sake quality). The choice between these affects the final flavor of the sake.
3. Shubo Making – Starting Fermentation with Yeast
After koji making, the next step is to prepare the “shubo” or yeast starter. Shubo serves as a foundation to proliferate yeast and advance fermentation. The flavor and aroma of sake are significantly influenced by this yeast.
There are two methods for preparing shubo: “sokujo-moto,” which involves adding lactic acid artificially to speed up fermentation, and “kimoto,” an older method that relies on natural lactic acid bacteria. Sokujo-moto is efficient and produces a stable yeast starter in a short time, often resulting in a clean and sharp-tasting sake. Kimoto, by allowing natural lactic acid bacteria to develop, takes longer but yields a sake with a deeper flavor.
- Sokujo-moto: An efficient method that involves adding lactic acid artificially to accelerate fermentation, producing a clear and sharp sake.
- Kimoto: A traditional method using natural lactic acid bacteria, taking more time but creating a deeper flavor.
The shubo making process takes about two weeks to a month, during which the yeast multiplies vigorously, preparing for alcohol fermentation.
4. Moromi Making – The Heart of Sake Brewing
Next is “moromi making,” where shubo, koji, steamed rice, and water are mixed to proceed with fermentation. This stage involves a unique process to sake called “parallel multiple fermentation,” where saccharification and alcohol fermentation occur simultaneously.
In moromi making, ingredients are added in three stages, known as “san-dan-jikomi.” This method helps maintain vigorous yeast activity and ensures stable fermentation.
- Hatsuzoe: A small amount of ingredients is added first to prepare the environment for the yeast.
- Nakazoe: A medium amount of ingredients is added on the second day.
- Tomezoe: Finally, the remaining ingredients are added to advance fermentation.
Fermentation continues for three to five weeks, during which the alcohol content increases to around 15%. The character and aroma of the sake are largely determined during this stage. Managing temperature and humidity is crucial. Additionally, whether the sake becomes sweet or dry depends on how fermentation is halted: stopping it early results in a sweeter sake, while letting it complete leads to a drier one.
5. Joso – Pressing the Sake
Once fermentation is complete, the next step is “joso,” where the moromi is pressed. There are several methods of pressing, but typically a “pressure press” is used to separate the sake from the lees. In special cases, a method called “fukuro-zuri” (bag hanging) is employed, where the moromi is placed in bags, and only the sake that naturally drips out is collected.
The pressed liquid still needs further adjustments before it can be consumed.
6. Pasteurization and Storage – Stabilizing the Sake
Freshly pressed sake still has active yeast and enzymes, which can destabilize the quality if left untreated. To prevent this, a process called “hiire” (pasteurization) is performed by heating the sake to 60-65°C for a few minutes to deactivate these components.
After pasteurization, the sake is stored for a period ranging from several months to several years, allowing the flavors to mellow and the aroma to become more refined. Longer storage periods can produce “koshu,” a special type of aged sake with a distinctive flavor.
7. Bottling and Finishing – Finally Complete!
After storage, the final steps include “blending” and “dilution.” During blending, sake from different tanks is mixed to adjust the flavor, and dilution lowers the alcohol content to about 15-16% to balance the drinkability.
After one last pasteurization, the sake is bottled and shipped out. This is how the delicious sake we enjoy makes its way to us.
Summary
As we can see, making sake involves a lot of detailed steps. From simple ingredients like rice, water, koji mold, and yeast, such a diverse and profound flavor is born. The next time you enjoy a glass of sake, remember this production process and appreciate the craftsmanship and effort of the brewers behind each sip.
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