The old-fashioned sake breweries operates from autumn to spring, when it is easiest to control temperature while while modern breweries with refrigeration and cooling tanks operate year-round,. Rice, rice koji and water are the three crucial elements in brewing sake.

The Sake Brewing Process

Like beer and wine, sake is a fermented brew. Although it contains 12 to 18 percent alcohol, it is classified as a wine because it is made from rice, which is a cereal. Unlike wine, sake has no sulfites and contains no additives or preservatives. And from process point of view, Sake is actually a beer; starch converted into sugar and the sugar converted into alcohol.


Sake is 80% water; therefore, high quality water is vital to producing high quality sake. The water most suitable for brewing sake is high in potassium, magnesium, and phosphoric acid. It must also have very low levels of iron and manganese, both of which can cause discoloration and diminish the sake’s flavor.


As rice is the key to the quality of the sake, so is the preparation of the rice. Sake’s quality is determined by how much of the outer kernel of the rice is milled away. The milling process removes the protein and fatty acids in each rice kernel, leaving the dense starch packet at the kernel’s center. It is this starch that will be converted to fermentable sugars. When more of the outer surface of the rice is removed, the sake produced achieves a higher quality, with a lighter, more delicate flavor.

The Process

After the rice has been polished to the appropriate size, it is rinsed, soaked and steamed. It is at this point that the quality of the water makes its presence known. From here, approximately one-quarter of the steamed rice is set aside for making koji. The remaining steamed rice is cooled and used for the fermentation process.

Koji plays the same role in the sake brewing process as yeast does in the making of beer and wine. It is made by sprinkling fungi spores (aspergillis oryzae) over steamed rice and maintaining it in a controlled, high-temperature, high-humidity setting for 48 hours. Koji and yeast are then placed together in a tank of water and mixed. Steamed rice is added next, the yeast begins to multiply, and fermentation begins. The fermentation process creates a mixture of liquids and solids. The liquid, removed by filtration, is sake. After the sake is extracted, it is pasteurized at about 62 ºC to terminate the enzyme activity. It may also be ultra-filtered to remove the enzymes.