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TEST > C9 - Preparing Koji - working > Flashcards

C9 - Preparing Koji - working Flashcards

1
Q

what happen to the koji mould if the temperature is cold and dry?

A

it will stop growing

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2
Q

how tsuki-haze influence the style of the sake?

A
  • it’s ideal for the slow, controlled, cold fermentation for making ginjo style
  • low level of lipid restricted the fungal growth
  • low level of vitamins and proteins give a more light texture and delicate style of ginjo aromas
  • it’s low acidity and low in umami
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3
Q

why barley can breakdown the starch without the aid of koji?

A

because malted barley (or rice with germ) can use germination to activate the grain’s own starch-to-sugar enzymes.

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4
Q

How koji-making machine do the “re-breaking up” process?

A
  • it uses the rotating roller to breakup the rice

- temperature and humidity a automatically preset

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5
Q

how so-haze koji perform during fermentation?

A
  • it is fast in starch to sugar conversion
  • usually use in a warmer and faster fermentation
  • it adds intense flavours, full body, high acidity and high umami to the sake produce.
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6
Q

What do middle work do (naka-shigoto)?

A
  • flattening the shape of the mound
  • drawing patterns on the surface
  • in order to increase the surface area of the mound
  • which help dispersing heat and evaporate water
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7
Q

why tsuki-haze is difficult to make?

A

it needs a great deal of skill to create

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8
Q

what are the main acid types of sake?

A
  • succinic acid
  • malic acid
  • lactic acid
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9
Q

what is box koji (hako-koji)

A
  • ~15 - 40kg medium size box
  • often with an divider for separating the rice to half in the box
  • labour intensive
  • suitable for style in between futsu-shu and daiginjo
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10
Q

how the koji mould breakdown the starch in a rice grain?

A
  • the koji mould sending it’s feeding tube (hyphae) into the rice grain
  • the feeding tube has enzymes hided by other components
  • the enzyme then breakdown the starch into glucose
  • the glucose are absorbed by the feeding tube
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11
Q

what is the ideal condition of the rice grain for growing tsuki-haze koji?

A
  • less moist, so the mould is harder to grow on the surface

- a firmer exterior, so the mould’s feeding tube is difficult to penetrate

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12
Q

what is “Bringing in (hikikomi)?

A
  • hour 0: it’s the starting point of making koji
  • steamed rice are cooled down to 32-35C
  • then the cooled rice are transferred to the koji room
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13
Q

why it needs a special koji room to grow the koji mould?

A

the koji-room (koji-muro) is temperature and humidity controlled.

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14
Q

how the koji-making machine do the middle work?

A
  • use rotating rollers to redistribute the rice and draw patterns
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15
Q

What is the aim of middle work (naka-shigoto)?

A
  • reduce the rice temperature from 36C to 33C, then rise to 38C
  • disperse heat
  • drying the rice
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16
Q

what cannot stop the mould growth by heating it?

A

Because heating will cause off-flavours and de-activate enzymes and vitamins created by the mould.

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17
Q

How many varieties of koji mould?

A

3:

  • yellow
  • black
  • white
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18
Q

how machines spread the spores and let it grow?

A
  • spores are sprayed to the rice when transferring from the steamer to the koji-making machine
  • rice are laid out in a large drum with temperature and humidity control
  • a rotating roller moves the rice
  • the machines creates a warm and humid environment to encourage mould growth
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19
Q

what is koji?

A

Koji is a culture of filamentous fungi grown on cereal grains.

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20
Q

When does the Middel Work (naka-shigoto) start?

A
  • hour: 30 - 33
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21
Q

describe the characteristics of so-haze koji:

A
  • the koji mould covers the entire rice grain surface
  • sending many feeding tubes deep into the rice core
  • it has high levels of enzymes, amino acid, vitamin, sugar and peptide.
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22
Q

What is the percentage of koji in most of the sake today?

A

around 20%

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23
Q

What is bed koji (toko-koji)?

A
  • rice is kept complete the koji-making process on the bed (toko)
  • the koji batch volume is around 100-300kg
  • not possible for the highest precision control
  • suitable for futsu-shu, junmai, honjozo.
  • possibly for some ginjo but not daiginjo
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24
Q

what is the alternative of making koji the traditional way today?

A

using half or fully automated koji-making machines

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25
Q

what is the aim of “Final work”?

A
  • focus shifted from dispersing heat to reduce the moisture
  • drying out the grain’s outside, encourage the koji mould to grow to the core of the grain
  • temperature of the rice is remain 38C, need to beware not to exceed 43C, otherwise the koji mould will under stress
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26
Q

why yellow koji is the mostly used in making sake?

A

because it has the lowest level of citric acid.

Acidity has been regarded as undesirable by sake drinkers for a long time.

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27
Q

how are the colours of the koji varieties come from?

A

the appearance of the koji inoculated rice grains

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28
Q

what was the limit of the koji-making machines in the beginning

A

it can only produce large scale but low quality koji

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29
Q

How’s the texture and aromas of Honjozo made with tsuki-haze?

A

it has a lean texture, and restrained aromas

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30
Q

what are the 3 options the brewer can choose to manage the moisture and temperature during Mounding (Mori)

A

using 3 different size of container for the koji:

  • bed koji (toko-koji)
  • box koji (hako-koji)
  • tray koji (futa-koji)
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31
Q

How’s the koji mould growth activity after mounding, means during middle work?

A

at its most vigorous

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32
Q

what are the difference of cooling the rice in traditional way vs by machine in the brining-in stage?

A
  • traditionally the steamed rice are spread on mat right outside the koji room
  • machine uses cooling conveyor to cool down the rice and send to the koji-making machine directly
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33
Q

what is “sending out (de-koji)”?

A
  • chilling the rice to ambient temperature to stop the mould growth
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34
Q

what is the main purpose of koji

A

to provide enzymes that break down the starches into fermentable sugars.

35
Q

how the brewer spread the spores when making hand-made koji?

A
  • the rice are spread on a large bed-like table (toko)
  • koji spores are applied using hand shakers
  • koji spores are spread in appropriate amount and evenly
36
Q

What is the risk of mounding if the temperature is keeping too high?

A

it will kill the mould

37
Q

what is the ideal environment for koji mould to grow?

A
  • warm temperature

- high level of water in the rice grain

38
Q

traditionally which material is used to cover the koji room?

A

Japanese cypress wood (hinoki)

39
Q

what are the 7 stages of making koji after the rice is steamed?

A
  • Bringing in (hikikomi)
  • Spreading the spores (tanekiri) and initial mould growth
  • re-breaking up (kirikaeshi)
  • mounding (mori)
  • bed koji (toko-koji)
  • box koji (hako-koji)
  • tray koji (futa-koji)
  • middle work (naka-shigoto)
  • final work (shimai-shigoto)
  • sending out (de-koji)
40
Q

what does Mounding (Mori) need to do?

A
  • hour: 20 - 23
  • temperature of the rice raise from 33C to 35C
  • rice is unwrapped, spread out
  • then move to a less humid part of the koji room
  • the aim is to manage the level and distribution (pattern) of the mould growth
41
Q

what are the two extreme styles of koji? what they call?

A

so-haze

tsuki-haze

42
Q

When to start the “sending out” (de-koji)?

A

hour 44 - 48

43
Q

what is the Japanese of “koji room”?

A

koji-muro

44
Q

what it needs to create the tsuki-haze koji?

A
  • the moisture level of the grain is controlled to low level
  • the amount of koji mould spores are limited
  • the koji room is relatively warmer and drier
45
Q

What is Mounding (Mori)?

A

to manage the koji mould growth pattern to achieve the desired koji style e.g. tsuki-haze or so-haze

46
Q

where the brewers get the koji mould from?

A

purchased from a small number of suppliers

47
Q

What happened in case the koji mould died during mounding?

A

died koji creates undesirable aromas and flavours like sweat, which taints the sake.

48
Q

why making koji the traditional way is very labour intensive?

A
  • temperature and humidity need to be checked every 2 hours

- the rice needed to be worked by hand

49
Q

what other components are provided by the koji mould while penetrating the rice grain?

A
  • amino acid
  • peptilde
  • vitamin
  • lipid and protein
  • other subtle aroma and flavour molecules
50
Q

describe what does “Re-breaking up (kirikaeshi)” do:

A
  • hour 10 - 12:
  • the temperature of the rice mound is raised to 33C
  • the mound is broken up by hand, to help the mould grow evenly and dropping the temperature to 31C
  • brewers work on the rice carefully and thoroughly to check and remediate any clumps and hot spots
  • the rice than wrapped up again, temperature is raised back to 33C, humidity is also raised.
  • the mould will keep growing for another 8-12 hours
51
Q

Which tools the brewers use to draw pattern on the mounds of bed, tray and box koji during middle work?

A
  • by hands: for the box and tray koji

- by using a “wooden plough” for the bed koji

52
Q

what is tray koji (futa-koji)?

A
  • ~1.5 - 2.5kg small size box
  • this allow the most precise control of temperature and water content in the rice
  • very labour intensive
  • for the best daiginjo sakes
53
Q

how is the temperature differ at the top and bottom of the containers with the koji rice?

A
  • it’s warmer at the top

- cooler at the bottom

54
Q

how the brewers adjust the mould growth rate in the containers to the same level?

A
  • they check and re-arrange the containers in every few hours
55
Q

How the rice are cooled down during “sending out” (de-koji) in the hand-making way?

A
  • the vessels (tray, box, bed) are transferred to a separate part of the koji room, that’s at a cool ambient temperature.
  • often use fans to blow cool air from below to speed up the cooling.
56
Q

What does the brewer need to pay attention to during mounding (Mori)?

A
  • the distribution of moisture and temperature of individual rice grain rather than the mass.
57
Q

what is the objective of some brewers trying to use black or white koji?

A
  • with the higher level of citric acid, to achieve a structure and balance similar to wine
58
Q

where are the main acids in the sake come from?

A

the fermentation starter and the yeast

59
Q

Will chilling the rice kill the koji mould?

A

no, it just de-activate it.

60
Q

What do “spreading the spores (tanekiri) and initial mould growth” do?

A
  • hour: 1-3 - after ‘bringing-in’, the initial mould growth till hour: 10-12 (~9 hours)
  • temperature of the rice rise from 20-32C till 33-35C
  • the aim is to inoculate koji spores to the rice grain and encourage mould growth.
61
Q

what is the effect of tsuki-haze during fermentation?

A
  • it has limited amount of enzymes
  • the enzymes are released slowly
  • the rice are broken up slowly
62
Q

what is ‘nuri-haze’?

A

uneven koji mould growth due to the moisture level of the rice grain is too high.

63
Q

what are the forms (formats) of the koji mould purchased?

A
  • powdered

- granulated

64
Q

why futsu-shu and premium sake both can use the so-haze koji?

A

futsu-shu:

  • it boots the flavour intensity
  • compensate for the dilution caused by adding jozo alcohol

Premium sake:

  • it adds intense flavour, full body, high umami and high acidity to the final sake
65
Q

how the other components provided by koji mould affect the style and quality of the sake?

A
  • amino acid and peptide are yeast nutrients and give umami flavour. slightly in acidity.
  • vitamin are also yeast nutrients
  • subtle aromas and flavours e.g. chestnut
66
Q

In using koji-making machine, how the level and pattern of mould growth are determined?

A
  • by adjusting the temperature, humidity or the machine

- using rollers to move the rice around

67
Q

what’s the difference in the powdered koji mould and granulated koji mould

A
  • powdered are koji mould spores

- granulated are rice with koji mould spores growing on it

68
Q

How koji-making machine do the “final work”?

A
  • keep using the rotating roller to reshape the rice, increase the surface area, encourage evaporation
69
Q

describe the initial koji mould growth when making hand-make koji

A
  • after inoculation, the rice are formed into a mound on the bed and covered by blanket to keep it warm and humid
  • koji mould spores start germinating and grow
  • the mould will generate heat when grow, temperature is being monitored and adjust if needed.
  • the mound of rice will be left like this for 8-12 hours
70
Q

what’s the other name of koji mould?

A

Asperguilus oryzae

71
Q

how half-mechanised handling the koji rice containers work?

A
  • the re-arrangement is moved by machine rather by hand
72
Q

describe the appearance of tsuki-haze?

A
  • the koji mould grows in a tiny spot pattern over the rice grain
  • inside the rice grain, only part of the center has the feeding tube penetrated
73
Q

Which material is now widely used to cover a modern koji room?

A

stainless steel

74
Q

after the rice are transferred (or not) to the containers, how long the mould continue to grow?

A

another 7 - 10 hours

75
Q

How to classify koji styles?

A

according to the level and pattern of the koji mould growth

76
Q

which koji variety is the mostly used?

A

yellow koji

77
Q

what are the changes happening in the koji-making machines today?

A
  • more artisan brewers are willing to adapt the machines

- the quality keeps improving by collecting and compiling database

78
Q

can sake be made entirely using koji?

A

yes, but just a few

79
Q

why brewers making ginjo sake prefer to use granulated koji?

A
  • it has fewer spores
  • the spores can cover the rice surface lightly and evenly
  • that’s required for making the tsuki-haze koji
80
Q

By law, what’s the minimum percentage of koji need to use in fermentation?

A

15%

81
Q

why most brewers use the powdered koji mould?

A
  • since it has no rice grain

- it is suitable to inoculate continuously with a constant density

82
Q

when to start the Final Work (shimai-shigoto)?

A

hour: 36 - 38

83
Q

What is the disadvantage of using koji-making machine?

A

it’s not possible to have very precise control like hand made.

84
Q

How the rice are cooled down during “sending out” (de-koji) using koji-making machine?

A

the temperature inside the drum is automatically reduced.

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