Definition and production
Considered ‘the drink of the gods’ by the Japanese, nihonshu sake, a fermented Japanese alcoholic beverage, has become an important symbol of Japanese culture. Made from rice, water, ‘koji-kin’ (a mould which secretes enzymes) and yeast, sake is generally served during meals.
Nihonshu sake is Japanese fermented beverage (like beer), and is made from rice, water, ‘koji-kin’ (a mould which secretes enzymes) and yeast. It has an alcohol content of approximately 15% and is generally served during meals. Considered ‘the drink of the gods’ by the Japanese, it has become an important symbol of Japanese culture.
Nihonshu sake: recipe in six stages
1. Rice preparation: polishing, washing and cooking
The first stage entails washing the rice to eliminate as many of the fats and proteins as possible located near the surface of the grain. The remaining part (between 30 to 80%) is called the ‘seimaibuai’ and concentrates all the starch in the grain. Once it has been washed – in some breweries this is still done by hand – the rice is then steamed.
2. Kome-koji propagation
Koji (aspergillus oryzae) is a mould frequently used in the traditional cooking of Eastern Asia, particularly in the preparation of miso and soya sauce. It is also used in the production of nihonshu sake to convert the starch present in the rice grains into fermentable sugars. Without this process, the yeasts would not be able to produce alcohol. The use of koji appears to be fairly simple, but in actual fact it requires in-depth knowledge of both traditional and scientific techniques: sprinkled over roughly 20% of the rice (isolated in a room where the temperature is carefully controlled), it propagates, converting the starch into glucose within 48 hours. The rice on which the koji propagates is called ‘kome-koji’.
3. Production of shubo
The ‘shubo’ (or ‘saké mother’) is a culture which increases the presence of yeast and continues the conversion of starch into glucose. The Kome-koji is mixed with water, yeasts and cooked rice. This mixture increases the production of glucose, encouraging the yeasts to multiply and the culture to gain acidity (to protect it from airborne bacteria). A reduced version of the final product is obtained. The alcohol content is already around 10%, but its production is strictly controlled: at this stage, it can jeopardize the multiplication of the yeasts.
4. Brewing and fermentation
Once the shubo is produced, it is added – like a spoonful of yoghurt to hot milk – to the vats; water and the remaining rice is then added (rice that has been cooked but not yet affected by the koji). This stage requires four days, the time it takes for the koji to convert the starch into sugar and for the rapidly multiplying yeasts to convert the sugars into alcohol. As these two processes occur simultaneously, this is called ‘multiple parallel fermentation’: a phenomenon unique to nihonshu sake, through which alcohol can reach up to 22% (the maximum level authorized by Japanese legislation). But to produce a sake that tastes well-balanced, the more traditional producers prefer a lower alcohol content. The period of fermentation can vary, depending on the quality of the nihonshu produced and the techniques used. However, it generally lasts between 20 days (for the simple honjozo and junmai) to 40 days (for dai-ginjo and junmai dai-ginjo), at temperatures ranging from 8 to 15°C. If the nihonshu being produced is a honjozo-type sake, it is at this point that the distilled alcohol is added (before pressing).
5. Bottling preparation: pressing and filtering
Once the alcohol has been produced and its maximum (or ideal) strength has been reached, the liquid has to be separated from the ‘kasu’ (made up of dead yeast, koji and any rice that is still solid). This is an essential stage since nihonshu sake cannot be legally sold in Japan without being pressed beforehand. The legal designation for nihonshu sake in Japanese is ‘seishu’, which means ‘clear alcohol’. ‘Doburoku’ refers to a non-pressed sake.
6. Preparing for sale: filtration, pasteurization, bottling and storing
Once the nihonshu sake has been pressed it is, theoretically, ready to be drunk. However, like wine, it is common practice to ‘perfect’ the sake to improve its final taste. Since the pressing process by which the sediment is extracted from the liquid is fairly rudimentary, many producers carry out a standard filtration. They then dilute their nihonshu sake using pure water to reduce the alcohol content. Pasteurization is also a standard procedure among most producers, since it prevents the nihonshu from re-fermenting or turning sour in the bottle. Pasteurization can be carried out by passing the sake through pipes immersed in hot water, but the higher quality producers only pasteurize after the nihonshu has been bottled. It is even quite common to pasteurize twice: once in the bottle (or just before) and a second time just before the nihonshu is released onto the market. As is the case for many wines and spirits, the most popular sakes are generally those that have not been pasteurized, reduced or filtered.