Sake consists of 80% water. The nutritional value of the water influences the growth of the koji mold and yeast.
Thus, the flavor of the sake will change a lot depending on the water used.
Sake that is brewed near the ocean, where groundwater often contains higher levels of minerals, can result in stronger flavors and richer textures. On the other hand, in mountainous areas, or areas with clay soil, the sake often becomes delicate with a softer texture. This is because the water is filtered naturally under the ground, losing some of the minerals along the way.
Traditionally, there are particular kinds of sake: sake in Nada region, Hyogo prefecture, and Fushimi area, Kyoto prefecture. Sake in Nada is called Otoko-sake, masculine sake, which means the sake has a heavier body with rough textures and flavors. This is because Nada is close to the seaside and the water contains a lot of nutrients.
Sake in Fushimi, on the other hand, is called Onna-sake, female sake, implying the texture of softness. The water of the Fushimi area is filtered through Momoyama-Kyuryu hills. Therefore, the water gets round which brings out the mild texture of sake.
Nowadays, however, brewers try to control the levels of magnesium, potassium, and phosphorus by repeatedly filtering the water to adjust the nutrients to their specific brewing style.
There are other critical elements in sake brewing: koji and yeast. Kojispores convert the rice’s starch into sugar. Then the yeast ferments glucose into alcohol and carbon dioxide. Both Koji and yeast also affect the textures and aromas of the final product.
In the next article, I will take a closer look at the science behind koji malted rice making and the alcohol fermentation process.