Japanese Sake Brewing Terminology
Even though it is simply called “sake,” the production methods and timing can vary greatly depending on the brewery. At Seko Sake Brewery, we would like to help you enjoy sake even more by introducing you to key sake brewing terms.
● 精米歩合Seimai Buai (Rice Polishing Ratio)
This refers to the percentage of white rice remaining after polishing the brown rice. Generally, the lower this number, the cleaner and more delicate the flavor of the sake; the higher the number, the richer and fuller-bodied the sake tends to be.
Junmai-shu uses rice polished to 70% or less.
Junmai Ginjo uses rice polished to 60% or less.
Junmai Daiginjo uses rice polished to 50% or less.
●火入れHi-ire (Pasteurization)
Finished sake is usually pasteurized twice—once before storage and once before bottling. This process, called hi-ire, involves heating the sake to 60–65°C to prevent flavor changes caused by residual yeast activity or spoilage bacteria (hi-ochi-kin). This heat treatment helps stabilize the quality of the sake.
●生貯生詰 Nama-chozo / Nama-zume (Unpasteurized Storage and Bottling)
In this method, freshly pressed sake is stored unpasteurized at a low temperature (below 5°C)—this is nama-chozo. Then it is bottled after pasteurization (nama-zume). This process allows the sake to retain a fresh, youthful flavor similar to newly brewed sake.
● 冷おろしHiyaoroshi
Sake brewed in winter to spring and pasteurized once before storage matures gently over the months. When autumn arrives and the outside temperature matches the storage temperature, the sake mellows, losing the rough edges of a new brew. If it is then bottled without a second pasteurization, it is called hiyaoroshi—a seasonal autumn sake.
● 無濾過Muroka (Unfiltered)
Sake is defined as the liquid extracted by fermenting rice, rice koji, and water, then filtering the mash (moromi). The liquid is separated from solids using cloth bags, and the resulting sake is clarified (oribiki) and often treated with activated charcoal to remove off-flavors (carbon filtration). Muroka means this charcoal filtration is skipped, leaving the sake with its natural complexity and richness.
● 生Nama (Unpasteurized)
After filtering, sake is typically pasteurized at around 60°C to deactivate enzymes and yeast. Bottling usually involves a second round of heating. Sake that skips both pasteurizations is called nama and must be stored in a cool, dark place. Once opened, the flavor changes quickly—but experiencing those changes is part of the enjoyment.
● 原酒Genshu (Undiluted Sake)
Sake naturally reaches an alcohol content near 20%, but water is usually added before shipping to reduce this level. Genshu refers to sake that has not been diluted. It can also be enjoyed over ice, according to personal taste.
● 吟吹雪Ginpu-yuki
Ginpu-yuki is a sake rice developed in Shiga Prefecture in the early 1990s, specifically for ginjo-style sake. It is a unique variety created by crossbreeding 山田錦“Yamada Nishiki” (as the maternal line), Japan’s most renowned sake rice, with 玉栄“Tamae,” a common sake rice in the Kansai region. It has excellent brewing properties. At our brewery, we use Ginpu-yuki exclusively for our special junmai, junmai ginjo (60% polishing), and junmai daiginjo (45% polishing) sakes.
