Overview of Japanese Sake Production
This is the first blog for me and about an overview of Japanese Sake production. I was moved back to my home town from Tokyo and took over this fmailly business. This blog here is also my study note.
Japanese Sake is made from rice, water and Koji (and Jozo alcohol (distilled alcohol) for some Sake). Preparing rice is the start of Japanese Sake production. Of course, rice is produced in green field (paddy) with nutrient rich soil and plenty water. Hence, the important starting point to make good Japanese Sake is soil and water. About this important topic, I would like to write later.
1, Rice preparation
1-1, Polishing (milling)
After harvesting, rice is stored and polished to the desired level by big rice-polishing machine. This process purpose is to remove lipids, vitamins and minerals that are rich in surrounding part of rice. In Sake production, such nutrients make undesiralbe flavour and taste, especially for Ginjo brewing. Rice has pure starch core in the center part. This part is used for Sake brewing. Polishing ratio is one of criteria of premium Sake grade. Basically, highly polished rice tends to have pure, lighter, less acidity taste like Ginjo or Daiginjo, and less highly polished rice tends to have more body, rich, more acidity and more umami taste.
(The photo from KIKUHIME)
This process is done to remove nuka (a powder of rice after polishing) and dust which are undesirable components by using washing machine. In case that the brewer needs intense water control, they use small batches and wash rice by their hand.
Rice is soaked into water after washing in order to arrange good water distribution within the rice grain. If the is highly polisehd, water absorbance speed is very fast. So, a stopwatch is used to perfect timing and the rice is soaked in samll batches.
"Outside is firm and inside is soft." This is ideal distribution of moisture. To make this, the rice is steamed not boiled. Steaming kills microbes and the heat changes the starch structure so that the "Koji enzymes" can break into sugars.
(The photo from KIKUHIME)
2, Making Koji
Rice is a starch that is a large molecules made up of sugar molecules. So, to make alcohol from sugar, starch needs to be changed into sugar. In Japanese Sake brewing, Koji enzyme (a kind of protein) produced from Koji helps this chemical reaction starch into sugar. For making Koji, the Koji mould spores sprinked on the steamed rice. The mould is called Koji mould and the mouldy rice is called Koji. This Koji making is conducted in special room which can control temperature and humid.
(Tray Koji: This Koji making method uses for Ginjo or Daiginjo brewing basically. The photo from KIKUHIME)
3, Fermentation starter
This is "mini fermentation". Steamed rice, water, Koji and yeast are mixed in small tank before main fermentation. In this step, the main purpose is to build healthy yeast population. To avoid contamination, brewer ueses acidic environment by lactic acid bacteria. This acidic environment spoilage the other microbes, and Sake fermentation yeast can thrive in this environment and build healthy yeast population.
(The photo from KIKUHIME)
4, Main fermentation
Fermentation starter, steamed rice, water, and Koji are mixed in this step. Brewers build the fermentation in stages to protect the fermentation from contamination over a period of 4 days.
Day 1: about 1/6 of the total adding
Day 2: no adding
Day 3: about 2/6 (1/3) of the total (twice volume of day 1) adding.
Day 4: about 3/6 (1/2) of the total (remaining 1/2) adding.
In this step, two chemial reaciton process are happening at the same time. One is starch-to-sugar process by the enzyme and the other is sugar-to-alcohol process by yeast. This is multiple parallel fermentation which is a typical process shown in only Japanese Sake brewing. When the fermentation reached the desired level, the fermentation is stopped by cooling the mash.
5, Filtration (adding distilled alcohol)
When the fermentation is stopped, the mash must be filitered through a mesh. This process is filtrataion. Before filitration, some brewers add a small ammount of distilled alcohol (jozo alcohol) to make Ginjo or Daiginjo style sake, because the aroma of Ginjo (typical aroma of Ginjo brewing) is dissolved in more alcohol than water and enhance the aroma and flavour of the Sake.
(Funa-Shibori: Traditional way of separating the liquid from the rice solids. These bags are laid horizontally in the tub called "Fune". The bags are pressured from above. The photo from KIKUHIME)
(Yabuta-Shibori: Accordion-like machine. This is modern industrial standard filtration. The photo from Masuda Sake Company)
6-1, Charcoal fining
Most Sake is fined by charcoal to remove the colour of the Sake. However, these days, some brewers doesn't take place this process, because charoal fining has a risk to remove some of positive flavours and characteristics and make Sake lighter.
To make Sake stable, most brewers take this process twice. They heat the Sake, and the heating kills the bacterias and microbes and destroy Koji and yeast. Many brewers release some unpasteurized Sake (we call it Nama). Unpasteurized Sake is lively and has fresh characteristics and aromas, but, they have short shelf life and keep them in refrigerator to avoid spoilage.
Small amount of water is added to adjust the percentage of alcohol volume of Sake for enjoyable consumption.
Most sake is stored in the brewery for a few weeks or sveral months to make Sake balanced before release.
After the storage, when the brewers tasted the Sake and decided to release, Sake is lined up at the Japanese Sake stores.
This is the outline of Japanese sake prodcution. I would like to keep studying more and write more details about each topics, for exmaple, yeast (for Japanese Sake), Sake specific rice, rice fields, more details about sake prodcution and more interesting story about Japanese Sake.