Sake is made with four simple ingredients: rice, water, koji and yeast. The vast range of sake’s flavors and aromas come from only these four components, along with a brewer’s style and technique. Certified sake brewing rice, or shuzo-kotekimai, only comprises 1% of the total rice production in Japan. There are around 20 types of rice that are used to brew this premium sake. The water used in sake brewing is almost always extremely soft, due to Japan’s high mineral content in its water and plentiful underground water, snow melt and spring water. Because sake is 80% water, it is a very important component to brewing. Fermenting sake requires two microorganisms, making sake the only alcoholic beverage in the world to use a multiple parallel fermentation. Koji, a mold, is needed to turn the rice starches into fermentable sugar, and the yeast converts the sugars to alcohol and CO2!
- Sake rice is polished, washed, soaked, steamed and cooled.
- Koji, a mold, is grown on a portion of the steamed rice.
- The yeast starter, or shubo, is made by mixing a portion of the steamed rice, koji rice, and water. The yeast is then added to this mixture.
- The shubo is moved to a bigger vat to make the moromi, or main sake mixture. Over the course of four days, portions of the steamed rice, koji rice and water are added three times, and the multiple parallel fermentation begins.
- Optional step: brewers sometimes add a small amount of distilled alcohol to enhance the flavors and aromas of the brew.
- After fermentation, the moromi is pressed, to separate the fresh sake from the rice solids.
- Optional step: brewers can add activated carbon to the fresh sake, in order to remove sake’s natural color and undesired flavors. If the brewer decides to leave it unfiltered, it is called a muroka sake.
- Optional step: brewers can pasteurize the sake after pressing and filtering, by heating the sake for 30 minutes at 150°F. If they skip this step, the sake is called a namachozo.
- Optional step: brewers add water to lower the alcohol content. If it is left undiluted, it is called a genshu sake.
- After water is added (or not), the new sake is bottled.
- Optional step: brewers pasteurize the sake a second time in the bottle. If they pasteurized it after filtering, but chose to not pasteurize a second time after bottling, it is called a namachozo sake. If the brewer chose to not pasteurize the sake at all, it is a true nama sake.