Both of Clearspring’s sake producers, Akita Seishu and Oki Daikichi, use traditional, hand-crafted techniques to create premium sake that offers a great taste and delicate aroma.

What is sake
Sake is a Japanese alcoholic beverage made from rice. Although sake is often associated with wine for its alcohol content and the way it is enjoyed, it is not the most accurate comparison. Ideed, most wine undergo a single fermentation process whereas sake is made from multiple parallel fermentation similar to the beer process.

How sake is made
The process itself is extremely complex, but in the simplest terms: the rice is polished, steamed and inoculated with a mould called koji-kin, that has the latin name of Aspergillus oryzae. Once the mould has grown on the rice, this mixture is known as koji. The koji is then added to more polished and steamed rice. The microscopic mould slowly breaks down the carbohydrates of the rice into simple sugars. These sugars, in turn, feed a yeast called moto, that has the latin name of Saccharomyces cerevisiae and is similar to the beermaker's yeast. While the mixture - called moromi - is left to ferment, it is the moto that produces alcohol. The fact that the mould and the yeast work simultaneously gives the process its name of multiple paralell fermentation. The moromi is left in a fermentation container for anything up to forty days. By the end of the process, the mixture has an alcohol content of 20%, giving sake the highest naturally occurring alcohol content of any beverage in the world. Water is generally added to bring this down to around 16-17%.

The ingredients
The majority of sake produced and sold in Japan is known as futsushu or ‘regular’ sake. This often has large amounts of distilled alcohol added, along with artificial flavourings and preservatives, and although some are perfectly drinkable, quality does vary considerably. Around 25% of sake produced, however, are designated as tokutei meishoshu, or special designation sake. These are generally considered to be premium sake, and must meet certain strict criteria laid down by the Japanese government.

Both Clearspring Tamaki and Shizengo sakes are officially classified as junmaishu which belongs to the tokutei meishoshu category. This means that no extra distilled alcohol is added to them and meaning that they are prepared with rice that, after polishing, less than 70% of its original size remains.

Precise rice polishing
Premium sake is made using special rice that has larger grains that regular table rice, and where the fats and fibres are concentrated around the outer part of the grain. One of the most important criteria used to determine the quality of a sake is what percentage of the rice grain remains after these outer parts are milled or ‘polished’ away. This figure is known as seimaibuai, and in short terms, the more a rice is polished, the more exclusive the resulting sake is. 
As mentionned earlier, a sake to be classed as junmaishu, this figure must be 70% or less.
If this figure is 60% or less, the sake is then called ginjoshu (or junmai ginjoshu if no distilled alcohol is added).
If this figure is 50% or less, the sake is then called dai ginjoshu (or junmai dai ginjoshu if no distilled alcohol is added).

Clearspring Shizengo sake has a seimaibuai of 60%, while the corresponding figure for Tamaki sake is 50%, meaning that both have the delicate aroma and subtle taste for which these standards of sake are renowned.

Yamahai: a special traditional sake
The moto, or yeast starter used to kick start the fermentation of the sake mixture, is made by the sake maker using yeast, koji, rice and water, and generally has a little lactic acid added to speed up its development. However, in case of Yamahai sake, the yamahai moto is made without the addition of lactic acid, and is allowed to develop naturally. This is a painstaking and time-consuming process, but it results in a sake that displays an uncommon degree of character and roundness of flavour.

Clearspring’s Tamaki is one such sake, making it a relatively rare and special sake drinking experience.

Pressing and filtering
Once the fermentation is complete, the mixture is carefully pressed and then filtered to remove the sake lees or kasu, and leave behind a beautifully clear beverage. The sake is also briefly heated to 65oC to kill bacteria. This process was being carried out long before Louis Pasteur gave his name to a similar procedure in the West.

Maturation
All that remains is for pure spring water to be added to the sake to bring the ABV down to around 16%, and it is then left to mature, generally for around six months, to allow the flavour to develop.

While in modern, large scale sake making factories the process is computer controlled throughout, traditional producers such as the ones Clearspring work with rely on their long experience to judge by sight, sound and taste how to get the procedure just right.