Rice Preparation

Question 1

Name the 4 processes of rice preparation

Answer 1

1. Polishing
2. Washing
3. Soaking
4. Steaming

Question 2

What’s the purpose of polishing rice?

Answer 2

Reduce levels of proteins, lipids, vitamins & minerals in the rice grain.

High levels of these lead to faster fermentation & add flavour, texture & acidity to the sake which is not desired.

Question 3

What is the purpose of soaking rice?

Answer 3

• Adjust the amount & distribution of moisture within the grain.
• To achieve an ideal moisture level of 30%
• helps the koji mould to penetrate to the centre
• helps the grain break up easily during fermentation.

Question 4

What is the purpose of steaming the rice?

Answer 4

• To sterilise and to gelatinise the starch. So the koji enzymes can break down the starch into sugar.
• To increase moisture level to the ideal 40%

Question 5

How long does it take to polish 600kg to 70% seimai buai?

Answer 5

Roughly 10hrs

Question 6

How long does it take to polish 600kg to 50% seimai buai?

Answer 6

Roughly 45hrs

Question 7

How long does it take to polish 600kg to 35% seimai buai?

Answer 7

Roughly 80-100hrs

Question 8

How long does it take for the rice to cool & reabsorb the correct amount of moisture?

Answer 8

Depending on climate, 3-4 weeks

Question 9

What is the purpose of washing rice?

Answer 9

• To remove any remaining nuka which will add undesirable components to the sake
• Not to let the rice absorb too much water at this stage
• For water absorbed to be absorbed evenly

Question 10

What is the ideal moisture level for soaking rice?

Answer 10

30-35%

Question 11

What happens when grains absorb too much water during soaking?

Answer 11

1. For koji making, mould will grow too quickly without producing the correct amount of enzymes
2. Breaks up too quickly during fermentation. Yeast will have access to high levels of sugar speeding up fermentation and required flavours do not develop.

Question 12

Name the 3 techniques used in soaking to achieve the correct moisture level in rice

Answer 12

1. Soaking in small batches
2. Using cold water to slow down absorption
3. Using a stopwatch

Question 13

Name the 3 factors affecting ideal rice soaking time

Answer 13

1. The more the rice is polished, lesser time to absorb water
2. Colder water of 8-15°C is absorbed more slowly by the rice
3. Brewer must consider initial & target moisture of rice

Question 14

How long does it take to steam 700kg of rice in a traditional steamer?

Answer 14

40-60mins

Question 15

What is used for steaming rice on a larger scale?

Answer 15

Continuous steamers

This process is faster, 30-40 mins, from steaming to cooling & many tonnes can be done in a day

Question 16

Name the 3 aims of the brewer during rice preparation

Answer 16

1. Reduce the levels of proteins, vitamins, minerals & lipids. (Polishing)
2. Adjust amount & distribution of moisture within the rice grain. (Washing & soaking)
3. Gelatinise the starch so the koji mould enzymes can break the starch into sugar (Steaming)