C8 - Rice Preparation - completed Flashcards
How many steps in preparing rice before brewing?
four
What are the four stages in preparing rice before brewing?
1 - polishing
2 - washing
3 - soaking
4 - steaming
rice’s moisture level below ?? can be stored for weeks or months safely?
15%
Why rice needs to go through the preparation steps before can be used for brewing?
because rice stored the energy in solid starch form rather than fermentable sugar.
What are the three main objectives in preparing rice?
1 - reduce the levels of proteins, lipids, vitamins and minerals in the rice grain
2 - adjust the moisture level of the rice grain, suitable for making koji and fermentation
3 - gelatinise the starch to allow koji enzymes to break it down into sugar
Example of how the rice preparation choices influence the final style of sake?
when targeting a robust and flavoursome style, can use a less polished rice and no need to be precise in water absorption rate.
Why polishing rate is important in grading the sake?
The maximum ratios of polishing rate are defined for most grades.
what are the component in the outer layer of the rice grain important for the growth of koji and the fermentation?
- protein
- lipid
- vitamin
- mineral
what if the non-starch components in the rice grain are too much?
it will accelerate the koji propagation and the fermentation
Also these aromas, flavours and texture are not desired if making ginjo style sake.
briefly, how the rice are polished?
- using a rice polishing machine with high-speed rotating rollers
- the process is slow and gentle
why the polishing process needed to be slow and gentle?
- to avoid the rice dried out and then cracked due to the heat and friction from polishing
When did the polishing machine become widespread and adopted?
- the first half of the 20th century
How brewers do polishing before the polishing machine is available?
by hand or by watermills
What’s the consequence of polishing rice by hand or by watermills?
it’s impossible to reach a very low polishing ratio (seimai-buai) e.g. 60%
When was the first modern vertical rice-polishing machine developed?
around 1930
what was the initial use of the first vertical rice-polishing machine?
making sakes for competition only
When was the vertical rice-polishing machine become popular?
until 1980s
Why the vertical rice-polishing machine became popular in 1980s?
- “ginjo bloom”
- and the required brewing techniques became widespread
describe the structure of a rice polishing machine
- rice tank on the top
- rice drop into the polishing column
- it has a vertical barrel
- with an whetstone roller inside
- a screen below the polishing column to filter the rice powder (nuka) removed
- polished rice grains are transferred back to the top tank to repeat the polishing
How long does it takes to polish 600 kg brown rice to 70% semai-buai?
around 10 hours
How long it takes to polish 600 kg brown rice to 50% semai-buai?
around 45 hours
What’s next after the rice polished to the desired seimai-buai?
rest to cool down and re-absorb the moisture lost during polishing
Why it’s important to rest the rice grains after polished?
cooling down and re-absorbing the moisture can avoid cracking due to sudden temperature change when it’s washed in the next stage.
One of the factors determine when to change the roller layer and polishing speed:
depends on the characteristics of the rice variety.