C12 - The Main Fermentation (Moromi) - completed Flashcards

1
Q

which stage in sake production determine the styles of the sake?

A

the main fermentation (Moromi)

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2
Q

what are the aims of the brewer in moromi?

A
  • avoid problems
  • balance of the two parallel processes
  • achieve the desired aromas and textures
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3
Q

what are the objectives in the 3 different stages of moromi?

A

1 - avoid contamination

2 - adjust temperature to balance the two parallel processes

3 - ending the fermentation

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4
Q

what fermentation temperature range are most of the sake use?

A

12 - 18C

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5
Q

how long does most of sake take for main fermentation?

A

21 - 28 days

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6
Q

what is the alcohol level achieved for most of the sake after main fermentation?

A

17 - 20% abv

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7
Q

what is the residual sugar level of most of the sake after main fermentation?

A

15 - 25 g/L

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8
Q

what is the fermentation temperature range for making ginjo?

A

10 - 12C

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9
Q

how long it takes to make a ginjo?

A

30 - 35 days

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10
Q

what is kasu?

A

the suspended particles of rice and yeast cells in the alcoholic liquid after fermentation.

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11
Q

what are the two key controlling mechanisms to achieve consistency?

A
  • proportion and timing of adding the ingredients
  • temperature, speed and time
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12
Q

what is the standard ratio of: steamed rice: koji: water?

A

80: 20: 130

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13
Q

why cannot add all ingredient in one go in the main fermentation?

A
  • the yeast population will be too diluted
  • amounts of conversion enzymes will be insufficient
  • risk of microbial contamination
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14
Q

what level is the koji in the shubo and the earlier additions?

A

high

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15
Q

why the shubo and earlier addition has a high level of koji?

A

to help the fermentation with a strong start

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16
Q

why can’t just add lactic acid to the main fermentation to reduce risk of microbial contamination?

A

that needs a large amount of lactic acid, which will make the sake too acidic

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17
Q

is the sandan jikomi a legal requirement?

A

No

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18
Q

In the Day 1 of sandan jikomi, how many ingredient is added including the shubo?

A

1/6 of the total volume

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19
Q

what is the fermentation temperature in the first day of sandan jikomi?

A

12 - 15C

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20
Q

what is “Odori” mean in Japanese?

A

dance

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21
Q

why it’s nothing to add in the day 2 (odori)?

A
  • give time for the yeast to multiply.
  • required for a balanced fermentation
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22
Q

what ingredients are added in the day 3 (naka-zoe)?

A

water, koji, steamed rice

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23
Q

how many ingredient is added in day 3?

A

2/6

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24
Q

during the middle addition (naka-zoe) and final additions (tome-zoe), the temperature is reduced to which range?

A

6 - 10C

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25
Q

how brewer lower the temperature in the 3rd addition?

A

replace some water with ice

26
Q

what does the brewer need to be accurate when building the fermentation?

A

must be very accurate in the amount and type of koji i.e. ratios of the ingredients

27
Q

how temperature affect both enzymes and yeast activities?

A
  • warmer > more active
  • cooler > less active
  • warmer: enzymes increase rate is slower than yeast consume sugar
28
Q

how temperature affect the quantity of enzyme needed?

A
  • warmer: 16 - 18C, more enzymes is needed to keep up with the demand of yeast
  • cooler: 8 - 12C, less enzymes is needed
29
Q

what will happen if the sugar concentration in the ferment is too high?

A
  • inhibit further starch conversion
  • result in a higher kasu ratio
  • unpleasant volatile acidity
30
Q

in the case of sugar concentration is too high in a ferment, what’s the consequence of adding water to dilute the sweetness?

A
  • excess water will lead to dilute, flat taste
  • low density of yeast will let to slow or fermentation stop prematurely
31
Q

what will happen if fermentation speed is far ahead of the starch to sugar conversion?

A
  • sugar level is reduced
  • the conversion of protein to amino acids and peptides slow down
  • the resulted sake will have a thin taste and low umami
32
Q

techniques used to controlling temperature:

A
  • using mats (formed or woven) wrap around the tank
  • insert ice to into the space between the mat and the tank for cooling
  • modern breweries use jackets on the outside of the tank
  • heat exchangers submerged into the fermentation mass
  • computer system controlled water circulation in the heat exchangers
33
Q

besides the techniques, what else is needed to control the temperature closely?

A
  • constant attention
  • small adjustment
34
Q

to make a rich junmai style sake, what should be the temperature range?

A

top end of the range, 16 - 18C

35
Q

to make a daiginjo style sake, what should be the temperature range?

A

lower end 10 - 12C

36
Q

what happen if the temperature is wrong for the desired style of sake?

A
  • impossible to create the desired style
  • because the desired aromas and flavours are not created
37
Q

when will the brewer decide to end the fermentation?

A

when the target level of sugar and alcohol are achieved

38
Q

why brewers lower the temperature when it’s near the end?

A
  • because high temperature and/or high alcohol concentration will increase the rate of dying yeast
  • which will create undesirable tastes and aromas in the sake
39
Q

what ingredients and conditions should be used for making a rich, high-umami style?

A
  • high polished ratio (70%+)
  • so-haze koji
  • higher fermentation temperature
40
Q

what is the result of using high polished ratio rice, so-haze koji and high fermentation temperature?

A
  • higher level of protein being broken down to amino acid and peptides
  • fast starch to sugar conversion to feed the yeast
  • vigorous fermentation
  • higher acidity, low aroma
  • richer tastes
41
Q

what ingredients and conditions should be used for making a ginjo style?

A
  • low polishing ratio rice (<60%)
  • use tsuki-haze koji
  • extremely cool conditions
  • fermentation temperate of 8 - 12C
  • long fermentation time 30 - 35 days
42
Q

what is the result of using low polished ratio rice, tsuki-haze koji and low fermentation temperature?

A
  • tsuki-haze convert the starch to sugar slowly, as well as amino acid nutrients
  • yeast growth is limited
  • fermentation is slow
  • acidity is low
  • low degradation of proteins
  • result is a light and smooth taste and texture
  • aromatic
43
Q

why ferment in low temperature produce a more aromatic sake?

A
  • because low temperature reduced the lost of esters by evaporation
44
Q

under what condition yeast will create increased levels of a particular group of higher alcohols?

A
  • cold temperature
  • shortage of nitrogen (or amino acid)
45
Q

what kind of higher alcohol will yeast number 9 create under extreme stress?

A

isoamyl alcohol

46
Q

what is ester?

A

the highly fruity or aromatic compounds produced by yeast when under stress

47
Q

how yeast produce esters?

A
  • in the enzymatic chemical reactions
  • yeast combine various alcohols with acetyl, caproyl-coA and other chemical groups to produce esters
48
Q

what are the most notable esters in ginjo?

A
  • isoamyl acetate (aromas of banana)
  • ethyl caproate (aromas of green apple or melon)
49
Q

what is the ideal temperature tolerance per day for ginjo fermentation?

A

0.3 - 0.5C

50
Q

why it is important to keep monitoring the ginjo fermentation?

A
  • if yeast nutrients is too high, the fermentation will run too fast.
  • it’s difficult to lower the temperature because it’s already in the lowest limit of yeast
51
Q

after a long fermentation at low temperature, what is the result in the remaining rice solid?

A
  • rice does not broken up as much
  • many rice solid remaining in the tank
52
Q

why leaving a lots of rice solid (kasu) in the tank is a good sign of quality for ginjo?

A
  • that means very little amino acid or organic acids are extracted
  • which create a very smooth texture and clean, delicate taste
53
Q

What is the ideal fermentation batch size (rice and water) range of brewing ginjo?

A

600kg - 1500kg of polished rice

800 - 2000 L of water

54
Q

How many liters of ginjo sake can be produced by 600 - 1500 kg of polished rice plus 800 - 2000 L of water?

A

720 - 1800 L. of sake

55
Q

how many junmai ginjo can be produced by 1 kg of polished rice?

A

about 2.5 L.

  • after water adjustment to 15% abv.
56
Q

how many junmai can be produced by 1 kg of polished rice?

A

about 2.6 L.

57
Q

why the yield of honjozo is higher than junmai?

A

due to the small amount of jozo addition.

58
Q

how many futsu-shu can be produced by 1 kg of polished rice?

A

about 5 L

59
Q

why futsu-shu can have a much higher yield?

A
  • more dissolved rice
  • higher level of extraction at the filtration stage
  • up to 50% of jozo alcohol addition
60
Q

typically what is the fermentation batch size of futsu-shu compare with junmai?

A

futsu-shu is 20 - 30 times bigger than junmai

61
Q

why futsu-shu ferment in such large size?

A

to lower the production cost.