About Sake

Sake production starts with selecting the right rice. Sake rice, or sakamai, is polished to remove the outer layers, leaving a starch-rich core that is essential for brewing. Some strains to look out for are:

Yamada Nishiki 山田錦 - known as the 'King of the Sake Rice', mainly grown in Hyogo Prefecture and often used in the brewing of premium sakes.

Omachi 雄町 - the oldest sake rice strain, originally from Okayama Prefecture and known for its earthy flavors.

Gohyakumangoku 五百万石 - mainly grown in Niigata and Ishikawa Prefectures, it has a slightly smaller grain size than Yamada Nishiki.

Miyama Nishiki 美山錦 - highly resistant to the cold, and so is often cultivated in northern Japan.

Dewa San San 出羽燦々 - exclusively grown in Yamagata Prefecture.

Hattanso 八反草 - mainly grown in Hiroshima Prefecture and is often used in breweries that practice traditional brewing methods. 

The rice used in sake is polished to remove the bran and outer layers. The more polished the rice, the purer the starch, which plays a significant role in determining the flavor of the sake. 

The percentage simply refers to the amount of rice grain which remains after the polishing process.

Rice polished to 60% or less is called Ginjo 吟醸 and rice polished to 50% or less is called Daiginjo 大吟醸.

Some premium sake contains rice polished to as low as 7%.

The climate and environment in which sake is brewed plays an important role in the process. Temperature, humidity, and the natural surroundings of the brewery can all affect fermentation and the final taste of the sake.

Cooler climates, such as those in northern Japan, enable slow, controlled fermentation, which enhances the development of delicate aromas typical of ginjo styles. In contrast, warmer regions accelerate the fermentation, which can intensify certain flavours but may make delicate aromas harder to achieve.

High humidity levels are advantageous for cultivating koji mould, consistent humidity allows koji mould to flourish, helping maintain uniformity and control in sake production.

Soil rich in minerals, such as potassium, phosphorus, and magnesium, can improve rice quality by supporting strong plant growth and aiding in starch accumulation.

Soil acidity affects how nutrients are absorbed by the rice plants. Slightly acidic soils (pH 5.5–6.5) are generally ideal for rice.

After polishing, the rice is washed to remove any remaining bran and soaked to absorb the right amount of water. This prepares the rice for steaming.

Large-scale breweries use automated washing systems, which provide consistent washing times and water levels, an efficient process for high-volume production. Smaller or artisanal breweries sometimes wash rice manually in small batches. This approach allows them to monitor the rice’s water absorption closely, adapting the process to match specific batch requirements.

Brewers carefully control the washing time to a matter of seconds, particularly for premium sake, where small differences in water absorption can significantly affect the final flavour profile. Some methods even gently sprinkle the rice with water instead of being fully submerged, this sprinkling technique helps control water absorption rates even more precisely.

The rice is steamed to soften it while keeping its structure intact. This makes it suitable for mixing with koji and yeast later in the brewing process. Proper steaming is key to ensuring that the rice absorbs water evenly during fermentation.

Breweries might choose to steam rice more lightly or more thoroughly, depending on the type of sake they want to produce. Hard steaming creates a firmer texture in the rice, which allows for slower breakdown during fermentation, often resulting in dry, crisp sakes. Soft steaming, on the other hand, produces softer rice that ferments more quickly, which can enhance sweetness and fruitier flavour profiles.

Tsumu-jikomi 積む仕込み - some traditional practices, sake breweries use a multi-layer steaming technique. The rice is steamed in batches or layers, with adjustments in each layer’s steaming time.

Water makes up about 80% of sake, it is a key ingredient, used in both brewing and dilution. The mineral content and purity of the water can significantly impact the sake’s flavor, texture, and overall balance. Some varieties to look out for:

Miyamizu 宮水 - from Nishinomiya in Hyogo Prefecture. Contains  high levels of potassium, calcium, and phosphorus but very low levels of iron. This mineral balance promotes yeast activity during fermentation.

Fushimizu 伏水 - from the Fushimi area in Kyoto Prefecture, a softer water than Miyamizu.

Uonuma Water 魚沼水 - a soft water from the Uonuma region in Niigata, a prefecture known for its snowfall and pristine mountain spring water.

Oita Spring Water 大分の水 - moderately soft water from Oita Prefecture, influenced by the region’s rich volcanic soil.

Yamagata Spring Water 山形の水 - moderately hard water from the mountains of Yamagata Prefecture.

Koji is a type of mold grown on the steamed rice that converts starches into sugars, which are necessary for fermentation. The process of creating koji is highly controlled, as it significantly impacts the sweetness and complexity of the sake.

The yeast starter, or shubo, combines rice, water, koji, and yeast to begin the fermentation process. This stage sets the foundation for how the sake will develop its alcohol content and flavor profile over time.

Fermentation involves adding more steamed rice, water, and koji to the yeast starter, creating the main mash, or moromi. Over the course of several weeks, this mixture ferments and develops the alcohol content and flavors of the sake.

Some breweries are known for using more traditional and labor-intensive methods of fermentation. 

Once fermentation is complete, the sake is separated from the rice solids by pressing. This step helps to define the final texture and clarity of the sake. Different pressing methods can affect the overall smoothness and flavor of the drink.

The first portion of sake to be extracted during pressing tends to have a robust taste and is called Arabashiri 荒走り.

The middle portion of the pressing is often the smoothest, most balanced, and most refined. It is called the Nakagumi 中汲み.

The final portion of pressing can be rougher in texture and is called the Seme 責め.

Filtration removes any remaining particles and impurities from the sake, ensuring clarity and refining its texture. Different filtration techniques can also affect the final flavor and aroma of the sake.

Coarsely filtered sake which retains many of the solid rice particles is called Nigori 濁り.

Pasteurization involves heating the sake to stabilize its flavor and prevent spoilage. This process ensures the sake maintains its quality during storage and transportation.

Sake is usually pasteurized twice: once after brewing, then the sake is allowed to mature, then the sake is pasteurized once again before bottling. 

Unpasteurized sake has a raw, fresh taste and is called Namazake 生酒.

While some sakes are enjoyed fresh, others are aged to enhance certain characteristics. The aging process can add depth to the flavor and alter the overall profile of the sake, depending on how long it is stored and under what conditions.

Shinshu 新酒 - "new sake," refers to freshly brewed, unaged sake which is typically released shortly after the brewing season.

Koshu 古酒 - "old sake" or "aged sake," denotes sake that has undergone maturation, usually for several years.

Choki Jukusei-shu 長期熟成酒 - "long-term aged sake" applies to sake specifically aged for an extended period, sometimes five to ten years or more. 

Before bottling, some sakes are diluted with water to adjust the alcohol content, typically to around 15-16%. Dilution softens the alcohol profile and balances the flavors.

Undiluted sake results in a higher alcohol content of around 18-20% and is called Genshu 原酒.