As the West discovers the distinguished flavors of Japanese rice wine and its ability to pair with all kinds of foods, sake continues to grow in popularity among consumers. Without further ado, let's find out how this Japanese alcohol is made, what role exactly rice plays throughout its composition and what is its unique fermentation process called double parallel fermentation .
1. Selection of ingredients
Although some ingredients will be added later, the basic elements that make up sake are water and rice . It is important to choose your spring water carefully because its minerality will have an effect on the taste of the sake. While more mineralized water will give a hard side to sake, less mineralized water will make the sake softer.
It is also very important to choose your rice carefully so that it is of the best possible quality, not all rice grown is equal. The rice used for sake is different from the rice we usually use for cooking. It is called shuzo koutekimaï while everyday rice is called hanmaï . Shuzo koutekimaï is larger, more resistant and above all richer in starch than hanmaï which, as we will see later, is of capital importance for the manufacture of sake.
Shuzo koutekimaï is also harder for farmers to cultivate because, being larger, it is located higher up on the rice ears and is therefore more subject to climatic hazards such as wind and typhoons. Losses are therefore greater at harvest time and the yield is lower for farmers, which therefore makes this rice more expensive compared to hanmai.
It is estimated that around 95% of the production of hanmaï in Japan is made for only 5% of shuzo koutekimaï. Of these 5%, only 1% is considered rice capable of making high-ranking sake called daiginjo . Consequently, every year there is a lot of competition between the different sake breweries in order to obtain this quality rice. The objective is often to make the best daïginjo possible in order to win competitions which elect the best sake, and thus increase the reputation of the brewery.
2. Rice polishing
The polishing of rice is called seimai and is due to the uneven distribution of elements in the rice grain. This means that the amino acids, fatty acids, proteins and starch that compose it are not dispersed homogeneously in the grain. While amino acids, fatty acids and proteins are located on the ends of the grain, starch resides at the very heart of the grain. It is therefore necessary to polish the rice grain in order to eliminate all the elements surrounding its starch and which would give bad taste to the sake.
Polishing is carried out using large grinding wheels which will gradually reduce the diameter of the rice grains and thus make them purer. This step is very important because it defines a large part of the final taste that the sake will have. Care must be taken not to break the rice grains as this could alter the final taste of the sake. Although there are actually other parameters that influence the flavors of the final sake, it is quite common to say that the more polished the rice grains, the better the sake will be.
Rice grains are generally polished until they have 60% of their initial mass, and sakes made in this way are then called ginjo. However, polishing can be taken further to remove more than 50% of the initial mass of the rice grains to obtain a high-ranking sake, the latter will then be called daïginjo. There are also very low quality sakes which are composed of raw rice grains and 100% of their initial mass, they are called genmai . Not all sake breweries take care of the polishing of their rice because the installation of the millstones necessary for the processes is relatively expensive. Therefore it is common to see breweries ordering 50% or 60% polished rice directly from farmers depending on their needs.
3. Washing the rice
Once the rice has been polished it is necessary to wash it in order to remove the light layer that has formed during polishing, this layer is called nuka . To do this, we soak the rice in fresh water. The length of time the rice will stay in the water will depend on the percentage of polishing of the rice grains and will influence the final taste of the sake. Therefore it is very important to control this duration carefully so as not to obtain rice that is neither too dry nor too mushy. This is the role of the master sake maker, called toji , he who supervises all stages of sake making. Some sake breweries automate this step but naturally the sake obtained will be of lower quality.
The rice washing process can last from one minute to several hours. The more polished the rice grains, the quicker the washing will be, conversely if the rice grains are thick it will take more time to wash them. Rice grains are generally left in water until they have absorbed 30% of their mass in water.
Once the rice has been washed, the residual layer called nuka is recovered and will then be redistributed in the food sector or used for high-end cosmetics. It is a white powder quite similar to that obtained with classic rice flour, however this one is of much better quality and is therefore not used for simple traditional rice cakes.
4. Cooking rice
Once the rice is well moistened, you will need to prepare it for the fermentation process. To do this, the rice is steamed so as not to make it too sticky and too humid in large vats called koshiki. Once again, it is up to the toji to control the cooking time in order to obtain quality rice. Cooking rice usually takes no more than an hour. Once the rice is cooked, it becomes hard on the outside and soft on the inside. 20% of the rice obtained in this way will then be used to make koji while the rest will be used for the fermentation process.
5. Making koji
Making koji is one of the crucial steps in making sake. We start by spreading the cooked rice to lower its temperature to 40°C then we install it in the koji chamber, called kojimuro . The rice is spread out on large boards called toko and in this room, the humidity and temperature are controlled with extreme precision. The temperature can range from 30°C to 35°C and humidity is abundant to encourage the proliferation of koji-kin .
Koji-kin are mushrooms that look like a green powder that are added to rice after cooking so that they release enzymes called amylases . These enzymes are essential in the manufacture of sake because they will destroy the starch molecule of the rice grains in order to make simple sugars, this process is called saccharification . Without it, it would be impossible to ferment rice because its starch molecule is too large to be transformed into alcohol under the influence of yeast. The simple sugars obtained in this way in the rice grains, on the other hand, can ferment into alcohol under the effect of yeasts during the fermentation process. Koji-kin is also used to make miso and soy sauce.
It is necessary to mix and stir the rice quite frequently so that it is completely soaked up with the koji-kin. This process usually lasts between 36 to 48 hours. Once done, the rice obtained is called koji and is harder than when it entered the kojimuro chamber because it is covered with a light down formed by the koji-kin. Additionally, a pleasant chestnut smell emanates from the koji once it is finished.
6. Manufacturing of the shobo (motorcycle)
Once the koji is finished, it is poured into a large vat where it will be mixed with spring water, steamed rice, lactic acid and finally, yeast . This manufacturing process is called sokujo and it will initiate the fermentation of the rice. The yeasts will multiply there and begin to produce alcohol while bubbles will form on the surface of the mixture called shubo , or moto. The mixture is then left to rest for around fifteen days before sending it to even larger vats so that the rice can ferment completely.
The yeasts used during the manufacture of shubo, and therefore indirectly of sake, are very important because they will have an influence on the smell of the final sake, but also on its flavors. Most of the time, sake breweries buy ready-made yeasts commercially because it is easier to use them, the toji being used to working with them. However, some breweries create their own style of yeasts themselves and although this is something very difficult, it is the detail that allows you to develop unique sakes over the long term.
7. Making moromi (main fermentation)
Once the shubo is ready, it is transferred to large vats of one to ten tons to ferment the entire rice. Steamed rice and spring water will then be added to the shobo on the first day of fermentation. It is important not to pour them too quickly so as not to dilute the yeast in the mixture, which could slow down or even interrupt the fermentation process. Nothing is added to the shobo on the second day in order to let the yeasts reproduce, but spring water and steamed rice are added to the mixture in larger quantities on days three and four of fermentation, from the same way as on day one.
Then follows a long period which can last from three to five weeks where the shubo will gradually become moromi . Throughout this period the mixture will be stirred in the tanks and the temperature will be carefully controlled, which can range from 8°C to 18°C depending on the progress of the fermentation process. Note that the lower the temperature, the longer the fermentation period will be.
It is at this stage of sake manufacturing that we find double fermentation in parallel . While the koji will break down the starch of the rice into sugar, the yeast will be responsible for transforming this same sugar into alcohol. The final moromi will have an alcohol content between 17% and 23%.
8. Sake pressing
Once the fermentation is completely finished, the moromi contains a lot of rice residue, called kasu , which will have to be gotten rid of. To do this, we put the rice in cotton bags and then spread them over large vats. Gravity will then cause the sake to flow drop by drop and therefore separate it from the kasu, which will be exported from the brewery to be used in cooking. This pressing process is called joso and it is important that the toji controls it carefully so as not to overpress the moromi. The pressing generally lasts a few days while all the sake flows out drop by drop.
9. Sake filtering
The sake obtained after the pressing stage is unfortunately not yet ready to be bottled. It is necessary to filter it in order to make it purer and adjust its taste and color. Once again, it is toji that this role falls. Filtering techniques can vary from one sake brewery to another, but the most common filtering method remains charcoal filtering.
Finally, the sake is left to rest for a certain time in order to separate it from the few sediments that could have passed the pressing and filtering stage.
10. Pasteurization of sake
The objective of sake pasteurization is to permanently stop the fermentation process by destroying any surviving microorganisms and enzymes. Sake pasteurization is generally carried out between 60°C to 65°C. It is important to carry out this last step correctly because otherwise the final taste of the sake will be altered.
The sake is finally left to rest for a period ranging from 3 to 12 months depending on the sake brewery, then it will be diluted with water in order to lower its alcohol percentage to around 15%.
All that remains is to bottle the sake and enjoy its rich flavors! 🍶