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WSET 3 -saké > Chapter 8: rice preparation > Flashcards

Chapter 8: rice preparation Flashcards

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1
Q

What is an disadvantage of rice?

A

The energy is stored in the solid starch, rather than fermentable sugars

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2
Q

What is an advantage of rice?

A

It can be stored for months without rotting as long as its dried to a moisture of 15%

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3
Q

What are the 4 steps to make the solid starch available?

A

-Polishing
-Washing
-Soaking
-Steaming

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4
Q

What are the 3 things a brewer is looking for to achieve during rice preparation?

A
  1. Reduce the level of lipids,proteins,minerals and vitamins (too high levels = faster fermentation and add flavours)
  2. Adjust the amount and distribution of moisture within te rice grain (helps koji mould to penetrate to the centre and helps the grain to break up more easily)
  3. Gelatinise the starch so that the koji mould enzymes can break the starch into sugar
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5
Q

What is the husk of rice?

A

-The hard outer that protects the grain
-Removed immediatel after harvest
-remaining: brown rice, polishing ratio of 100%

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6
Q

What is in the bran?

A

-Starch
-Also: proteins,lipids,vitamins and minerals

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7
Q

Is the bran often used with sake production?

A

-No, it is made up from different layers and turns the rice from brown to white during polishing
- rarely used for sake production (although permited with junmai) because its difficult to propogate koji mould on bran and an excess amount of nutrients would make fermentation control difficult = unbalanced, rough flavours

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8
Q

What is the germ?

A

The part of the grain that will grow into a new rice plant

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9
Q

Is the germ removed during polishing?

A

Yes

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10
Q

What is endosperm? What does it contain?

A

-The white layers below the bran
-Very high in starch, outer layers also contain protein, lipids etc = much lower in sake specific rice than table rice

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11
Q

What is shinpaku?

A

-Only in sake specific rice
-Clearly defined section at centre of endosperm
-made with round-shaped granules of starch that are held in place by surrounding endosperm

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12
Q

What are the advantages of a Shinpaku?

A

-Good at absorbing water: soft part, absorbs water quicker
-Very suitable for koji making: koji propagates more easily

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13
Q

What are the differences between yamada Nishiki and Omachi regarding the Shinpaku?

A

-yamada= disc-shaped shinpaku (ideal for polishing to a low polishing ratio)
-Omachi = big ball-shaped shinpaku but cracks more easily during polishing and rice washing
-bigger shaped shinpaku not always good results in sake making

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14
Q

How is sugar stored in most plants?

A

-Sugar is vital for life, living things want reserves of sugar to support them in an event of shortage
-storing sugar not space efficient, can be dissolved when it comes into contact with water easy way is storage in starch

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15
Q

When a starch molecule is extending by adding another sugar molecule, 2 things can happen. Explain

A

-Simplest: sugar molecule is added at the end to make the starch chain lonfer withou changing its shape
-Or: can be added to create a side branch to the starch molecule

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16
Q

What is amylose?

A

Structure with an almost straight chain of glucose

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17
Q

What is amylopectin?

A

The latter structure with branches

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18
Q

When is the rice sticky/glutinous?

A

When the starch molecules in a rice grain are made up of 80-100% amylopectin

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19
Q

When is the rice non-sticky/non-glutinous?

A

If a rice grain contains less than 80% amylopectin and at least 20% amylose

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20
Q

Where does increased amylose content leads to?

A

Reduces enzymatic digestibility

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21
Q

How do rice grains store starch?

A

Starch molecules are rolled up into granules stored within the cell walls
-space efficient way to store sugar
-Cell walls act as a barrier to protect the tightly bundled starh from being dissolved in water

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22
Q

What is gelatinisation?

A

-Process where the tightly wound starch granules are unravelled by breaking into intermolecular bonds beween starch molecules
-Opens up the starch chains so they become water soluble nd can be broken up by enzymes dissolved in that water

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23
Q

What does gelatinisation require to take place?

A

Heat, thus takes place during steaming

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24
Q

What are the temperatures for rice gelatinisation? how is it compared to other cereal grains?

A

-70-80 degrees, relatively high

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25
Q

Name 1 reason why koji enzymes are needed for enzymatic hydrolysis

A

Because the temperature is too high for the rice germ’s own enzymes

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26
Q

What happens during enzymatic hydrolysis?

A

-It breaks the starch grains into glucose molecules
-needs: water and amylase enzymes
-alpha amylase breaks the non-branching amylose starch chains into smaller fragments = dextrins

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27
Q

What happens after starch chains are broken up into smaller fragments (dextrins)?

A

-Glucoamylase can then remove the glucose molecules at the end of the chains
-CANNOT separate the glucose where there is an amylopectin branch in the starch molecule

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28
Q

what is the remaining branched fragment called?

A

Limit dextrin

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29
Q

Do dextrin fragments remain in the sake?

A

Yes, giving a sticky mouth coating texture to the liquid

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30
Q

When does enzymatic hydrolysis take place?

A

during fermentation, a.k.a. enzymatic digestion

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31
Q

If a robust and flavoursome style of sake is sought, what are the choices the brewer will likely make?

A

-fast fermentation at higher temperature
-higher levels of koji
-rice does not have to be sake specific nor highly polished

32
Q

If a producer seeks to make a delicate, light-textured daiginjo, what choices will he make?

A
  • polishing the rice to low ratio
    -careful washing, good soaking and steaming to produce the right amount of koji because if enzymatic digestion is too quick, too fast fermentation
    cold, slow fermentation to produce fruity aromas
33
Q

Which nutrients are important for the growth of koji mould?

A

-bran and outer layers of the endosperm contains protein,lipids,vitamins and minerals which are important for the growth of koji mould and yeast.

34
Q

What happens with koji if there is a lot of protein, lipids etc available?

A
  • higher koji mould propagation
    -fast fermentation
    -large amount of sugar (due to koji propagation) + warm fermentations
    = difficult to have elegant flavuirs that need a long and cool fermentation in order to develop.
35
Q

What is the taste called as a result from rice proteins? what if there are too many rice proteins?

A

-Umami
-too many = rough and heavy texture

36
Q

Why does sake need to be polished slowly and gently?

A

Otherwise the rice grains dry out and become cracked due to the heat and fraction generated by the polishing

37
Q

What is used for polishing now and traditionally?

A

-Now: high-speed rotating roller
-traditionally: pedal-driven mills or by watermills, 80-90% max polishing ratio

38
Q

How does a vertical rice polishing machine works?

A

-Brown, unpolished rice is dropped into the polishing column
-rock grinding roller rubs away the outer layers of the grains of the rice

39
Q

What is the fine rice powder called which remains from the vertical rice polishing machine? Where is it used for?

A

-Nuka
-not use for sake, sold for rice oil, animal feed, rice cakes and glue

40
Q

What are the 2 stages of polishing?

A

-coarse grinding roller rapidly removes bran and endospwem
-switches to finer-textured grinding roller with a slow speed for a later stage where rice gets smaller and more fragile

41
Q

Where is the nuka separated from the rice?

A

Below the polishing olumn at the bottom of the machine

42
Q

Why are the rice grains sent back to the top of the tank?

A

To be polished until the grains are polished to the required ratio

43
Q

How long does it take to polish 600 kg of brown rice for honjozo level?

A

10 hours to reach 70%

44
Q

How long does it take to polish 600 kg of brown rice for daiginjo level?

A

45 hours to reach 50%

45
Q

What happens after the polishing ratio (seimai-buai) is achieved? why?

A

-Rice is rested to be cooled down and reabsorb some of the moisture lost during polishing
-Reduces the risk of cracks appearing on the rice caused by temperature change
-cooling & moisture can take 3-4 weeks

46
Q

What is the purpose of washing?

A

-Removing remaining nuka without allowing the rice to reabsorb too much water
-Water that is absorbed, absorbed evenly by the grains

47
Q

What are the 2 options for washing?

A

-Hand washing in small batches (traditional, premium sake)
-Rice washing machines -> now also as good as hand washing

48
Q

How does a rice washing machine works?

A

-Blow fine air bubbles through the water replicating hand stirring
-Brings all rice in contact with the water and gets the dusts off the rice

49
Q

How are futsu-shu sake washed?

A

-large-scale washing tanks

50
Q

What is the purpose of soaking?

A

-To increase its water content to the optimal level before steaming
-Moisture level raised to 30-35% depending on the rice variety and polishing ratio and if rice is used for koji or not

51
Q

What happens is the sake is soaked too long? what are the reasons why it is not good for quality?

A
  • The outside of the grains absorb too much water
    -2 reasons: (1)if rice is destined to become koji, mould will grow too quickly without producing sufficient koji enzymes
    (2) if over moist rice is used for fermentation, enzymatic digestion happens too quickly resulting in yeast having access to high sugar levels -> hard to control for brewer, not wanted for (dai)ginjo
52
Q

The more the rice is polished the less time is takes to absorb the water (true or false?)

A

True

53
Q

Does it get more difficult to enzymatically digest the rice in hot summers? how can this be compensated?

A

Yes, can be compensated by longer soaking

54
Q

Rice firmness/absorbency is for all rice varieties the same (true/false)

A

False

55
Q

Warmer water is absorbed by the rice more slowly (true/false)

A

False, cold water is absorbed more slowly (between 5-8 degrees) but water temperatures can change due to ambient temperature

56
Q

The brewer must consider the target moisture level of the rice (true/false)

A

True

57
Q

What does the brewer do to achieve the target water absorption?

A

Starts with a few trial batches, experimenting with adjustments by checking the rice and measuring the water absorbed each time

58
Q

Why does rice with a lower polishing ratio (<50%) absorb water more quickly?

A

Is drier and more porous and therefore absorbs water more quickly

59
Q

What happens if rice with a low polishing ratio is left to soak?

A

It will continue to absorb water, way more than the ideal 30%, thus it should be controlled especially for ginjo styles

60
Q

Does rice with a high polishing ratio (70%+) absorb water slowly or quickly? Why?

A

-Slowly because starts off with more moisture
-The rate of water absorption slows with time
-When it reaches 30%, water is hardly absorbed -> does not need to be monitored, can be left overnight to soak

61
Q

What are 3 ways to control and achieve the right moisture level?

A
  1. Soaking the rice in very small batches
  2. Using cold water to slow down absorption
  3. Timing the soaking using stopwatch
62
Q

What happens after soaking?

A

-Rice must be drained
-Left to rest several hours before steaming (less than 24 hours after soaking is finished)

63
Q

Is soaked rice more fragile than unsoaked rice? why (not)?

A

-Yes because of the increased moisture level in the grains

64
Q

What are the 3 purposes of steaming?

A

1.Sterilises the rice
2. Gelatinises the starch molecules
3. Further increase of moisture level (30% after soaking, 40%
after steaming)

65
Q

Explain how the traditional steamer is used and what needs to be considered

A
  • Rice has to be well drained
    -Rice placed in steamer at night or on the morning of steaming
    -1 batch = 700 kg and steaming takes about 40-60 minutes
    -rice loaded into the steamers in layers separated with cloths (easier to load/unload steamer and separate the batches)
66
Q

What is the aim of steaming regarding the grains?

A

-to be evenly cooked
-firm on the outside and soft on the inside

67
Q

Does rice used for koji production require higher or lower moisture levels? why?

A

-Higher levels to minimise cracking of the koji rice during steaming

68
Q

Which layer in the steaming machine is used for koji production?

A

Top layer because it is easier to control the moisture level and minimising cracking compared to other layers

69
Q

Why is the rice steamed in cloths?

A

To prevent the water condensation from surfaces dripping back onto the rice and making it wet

70
Q

The rice in the other steaming layers are used for…

A

The fermentation starter or the main fermentation

71
Q

In which layer are the moisture levels the highest? what problems can this cause?

A

-At the bottom of the steamer
-Moisture levels can be too high, problem if the rice has low polishing ratio and used for ginjo style

72
Q

What can brewers do to prevent too high moisture levels during steaming?

A

-Use bags of fake rice for the bottom of the steamer in order to raise the rice away from the steam and prevent the rice on the bottom layer from becoming too moist

73
Q

What is a different technique regarding steaming some brewers use? How does it work?

A

-Special pressure heater to blow dry hot steam just before the steaming process is finished
-Increased pressure raises the steam temperature and reduces the quantity of water droplets carried in the steam
- Leaving more heat and less water on the outside of the rice -> firm on outside, soft on inside

74
Q

Which steamers are used for large scale production? How does it work?

A
  • Continuous steamer: conveyor (rice on one side and exit for steamed rice)
    -1st part: high pressure steam
    -2nd part: rice is cooled
    -30-40 minutes, many tonnes of rice per day
75
Q

How do brewers decide if the rice is perfectly steamed?

A

-They shape rice into a round cake using their hands
-Toughness is checked (as hard ad a tennis ball when squeezed)
-Some check by chewing it with their front teeth

WSET 3 -saké (9 decks)

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