Seimaibuai

Seimaibuai, or seimai buai, is a term used in sake production to describe the rice polishing ratio. It denotes the percentage of the rice grain that remains after milling away the bran and outer layers. For example, a seimaibuai of 60% means 40% of the grain has been milled away and 60% remains. The polishing process removes fatty acids, proteins, and minerals concentrated in the outer layers, which can influence aroma, flavor, and texture in the finished sake.

Seimaibuai is a key factor in sake classification and style. The main premium categories specify milling thresholds: ginjo and junmai ginjo are typically produced with a seimaibuai of 60% or less, and daiginjo and junmai daiginjo are produced with 50% or less. In practice, lower numbers indicate more extensive milling, which tends to yield lighter, more delicate flavors and a different aroma profile. Other categories, such as honjozo and junmai, do not have a fixed milling requirement by law, and producers may mill to a range of ratios. Nevertheless, many premium honjozo and junmai styles also employ relatively high polishing compared with standard table sake.

Labeling often includes the seimaibuai, giving consumers an indication of the level of milling used. The degree of polishing interacts with other factors such as yeast, koji, and water to shape the overall balance, aroma, and palate of the sake. The concept originated in Japanese standards for sake production and remains a central descriptor in modern brewing.