Chapter 2: An Overview of Sake Production Flashcards
What are the ingredients of sake?
Steamed rice, Kōji, water and yeast
What are the two main subspecies groups of Asian rice?
long-grained (Indica) and short-grained (Japonica), which are further subdivided into sticky (glutinous) and non-sticky (non-glutinous).
What type of Asian rice does sake brewers use?
Non-sticky version of short-grained rice.
Can high-yielding, easy-to-grow table rice varieties be used for sake brewing?
Yes
Why are some harder to farm and lower yield special varieties developed for sake brewing?
They make it easier to separate cleanly the starch from the proteins and other undesirable parts of the rice grain:
- they contain less protein than table rice
- Most of the starch lies in a well-defined and almost pure starch core at the centre of the rice
- They are larger-grained, and therefore less likely to crack when polished
Name the processing steps before rice is used in sake production?
- Polishing
- Washing
- Soaking
- Steaming
What is the purpose of polishing rice?
Remove the proteins, lipids, vitamins and minerals that are concentrated in the outer part of the rice grain, leaving just the starchy core.
What is the polishing ratio?
The percentage of rice that remains after polishing
What process happens to the rice grain after polishing? and why?
The rice grain need to be cleaned to remove any remaining fine rice powder. If they remained, thy would make the sake less pure, and more rough-textured and acidic. The powder is removed by washing.
What does the rice polishing ratio (and the relative proportion of proteins, lipids, vitamins and minerals that remain) affect?
The style and the category of the final sake
What are characteristics of a sake made from rice with a low polishing ratio?
Tends to have purer, fruitier flavours and is lighter in body with lower acidity and umami. Sake made from the most highly polished rice can be used to make one of the ginjō styles of sake.
What are characteristics of a sake made from rice with a high polishing ratio?
Tends to have more cereal and less fruity flavours, with more body, more acidity and more umami.
What are the processes after rice is polished and washed?
Soaking and steaming
What are the purposes of soaking then steaming the rice?
- Raising the moisture level within the grain
- Changing the starch
- Disinfection of the rice
What is starch?
A large molecule made up of lots of sugar molecules all linked together in a chain
What are enzymes?
Enzymes are chemical that break up the rice starch into sugars before the sugars can be fermented by the yeast into alcohol. It is a kind of protein that helps chemical reactions to take place without being used up in those chemical reactions, therefore only small amounts of the right enzymes are needed to convert large amounts of starch into sugar
Where are enzymes in the nature world?
Any living thing that can digest starch has them. Starchy cereal grains also have enzymes to convert their space-efficient starchy store back into sugar before they can use that sugar to provide energy to grow into a plant.
Does sake use malted grains like beer to convert starch into sugar?
No. Sake is made from polished rice: the bits that could have grown into a plant have been removed, along with any starch-converting enzymes. Therefore, a mould that creates starch-converting enzymes is allowed to grow on some of the rice. This mould is called kōji mould and the mouldy rice is called kōji.
What is kōji?
Mouldy rice, where the kōji mould creates starch-converting enzymes.
What’s the proportion of rice in sake brewing is converted into kōji?
About 1/5 or a quarter
What are the ideal conditions for kōji mould?
High humidity and warm temperatures of between 33 degrees and 38 degrees.
What are the four main objectives in the process of making kōji?
- Cooling (Step 1): the portion of steamed rice that will become kōji is cooled to the right temperature.
- Inoculation (Step 2): the cooled steamed rice is transferred to the kōji room and spread out thinly over a table. Kōji mould spores are sprinkled on it.
- Initial mould growth (Steps 2-3): the warm and humid conditions in the kōji room encourage the spores to grow into the mould. The mould spreads and grows over all of the grains of steamed rice. The rice is thoroughly mixed to ensure that the growth of mould is even.
- Controlling and stopping the mould growth (Steps 4-7): The rice is then sometimes transferred to racks and moved to a cooler, less humid location in the kōji room. The aim of the brewer is to control the temperature in order to slow the mould growth so that exactly the right amount of mould can be grown on each grain. Ultimately the mould growth is stopped when the rice is finally moved out of the kōji room to a location that is cool and dry. Fans are sometimes used to help with the cooling process.
How long does the whole process of making kōji take?
about 2 days
Describe the finished kōji.
Looks like polished rice but has a crumbly texture, a delicate roasted chestnut aroma and is slightly sweet.
Describe the different styles of kōji.
- kōji with high levels of kōji mould enzymes — large amounts of kōji mould covering and penetrating the entire grain, means that large amounts of enzymes and nutrients are secreted. Therefore, starch is more rapidly converted into sugar in the fermentation tank. As a result, the fermentation is faster, and the sake tends to have more flavour intensity, with more acidity and umami.
- kōji with low levels of kōji mould enzymes — tiny amounts of kōji mould, dotting the outside of the grain, means that smaller amounts of enzymes are created. Also, because much of the growth occurs within in the grain (rather than on the surface), the enzymes are released more slowly into the fermentation. Consequently, there is a slower conversion of starch into sugar during the fermentation. The fermentation is therefore slower, and the sake tends to be lighter in flavour, with less acidity and umami.
This style of kōji requires extreme precision during the rice polishing, washing, soaking and steaming, as well as in the kōji room. Therefore typically used in order to produce the purest, most delicate styles of ginjō.
Why do sake brewers add water?
To make rice into a fermentable liquid
How much of the final sake is added water?
Over 80%
What types of water can be used for sake brewing?
As long as it is clean, and iron concentration is low, almost any water can be used.
Does water affect sake style?
Yes. Mineral concentration affects the fermentation and therefore the style of the sake.
What are the particular conditions of sake fermentations that require special yeast strains?
- they must keep working when the alcohol level is high (can be over 20% abv)
- often have to work in cold conditions (e.g., the fermentation temperatures for ginjō sakes can be as low as 6 degrees)
- limited supply of food (ginjō fermentations can have very low levels of sugar)
