Crafting exceptional saké begins with understanding the four ingredients at the heart of the process: koji, yeast, water, and rice. Each plays a distinct and irreplaceable role, shaping everything from aroma and texture to depth of flavor and overall character. Though saké appears simple—just rice, water, koji, and yeast—the transformation of these ingredients is a precise and nuanced craft refined over centuries. The following sections explore how each component contributes to the art of saké brewing and why their quality matters so profoundly.
Koji
Once upon a time—not all that long ago—a key step in making saké involved chewing rice and spitting it into a vessel. The enzymes in human saliva helped break down the grain. Fortunately, that step is long behind us, but the process it replaced remains a most sacred stage in saké production: making koji.
Enter koji (Aspergillus oryzae), a mold cultivated on steamed, cooled rice. As it grows, it produces enzymes that convert rice starch into fermentable sugars. Koji spores are sprinkled over the rice, which is then carefully tended under precise temperature and humidity conditions. Even slight variations in heat, time, or moisture can dramatically affect the quality of the koji.
In addition to enabling fermentation, koji contributes a significant amount of flavor and character to saké, making it one of the most essential ingredients in the craft.
Yeast
Like beer and wine, saké relies on yeast for fermentation. Once rice has been polished, washed, steamed, and inoculated with koji, the once-hard, inedible grains are transformed into soft, sweet kernels—ideal food for yeast.
Brewers have access to roughly 14 commercial yeast strains, each offering its own distinctive aroma and flavor profile and interacting with the rice in unique ways. Yeast selection is intentional, chosen to achieve a specific style or expression.
Some long-established breweries in Japan also maintain proprietary yeast strains that have been cultivated in their kura for decades—or even centuries. These strains contribute a singular character to their saké and, when combined with local rice and water, create a true expression of terroir.
Water
It may seem obvious that water is essential, but its importance in saké brewing is often underestimated. Saké is roughly 80% water, and the quality of that water profoundly affects the final product. Ideal brewing water is low in minerals and contains little to no iron, which can darken the saké and create off-aromas and flavors, as well as accelerate aging. Manganese is also undesirable because it reacts with light, causing discoloration and compromising appearance and character.
Beneficial minerals—such as potassium, magnesium, and phosphoric acid—support healthy yeast activity and proper koji development. The flavor of the water matters as well, since the same water used for brewing is often used to dilute the finished saké to achieve balance and refine flavor.
At SakéOne, our water originates on the eastern slope of the Oregon Coast Range, where deep aquifers collect the region’s abundant rainfall. As the water filters through organic sediment, igneous rock, and layers of basalt, it develops a naturally balanced mineral profile: crisp, clean, low in iron and manganese, and perfectly suited for brewing elegant, aromatic ginjo-style saké. This exceptional water is the foundation of our craft.
Rice
Rice is the foundation of saké, and while there are many varieties, only a select few—much like wine grapes—are truly suited for brewing. Over centuries, specific strains have been cultivated for their ideal grain size, hardness (which affects milling), aroma, and flavor. Today, roughly a dozen varieties are considered premier for saké production.
Regional rice varieties carry deep local pride and impart distinctive regional character to the saké they produce. While knowing the exact rice used in your favorite saké isn’t essential, it can be a helpful guide when choosing your next bottle—especially if you’re seeking a similar style or flavor profile. Back labels and brochures often list the rice variety used.
Some of the most commonly seen names include Yamadanishiki, Gohyakumangoku, and Omachi—all celebrated for their unique contributions to premium saké.
