C12 - The Main Fermentation (Moromi) - completed Flashcards
which stage in sake production determine the styles of the sake?
the main fermentation (Moromi)
what are the aims of the brewer in moromi?
- avoid problems
- balance of the two parallel processes
- achieve the desired aromas and textures
what are the objectives in the 3 different stages of moromi?
1 - avoid contamination
2 - adjust temperature to balance the two parallel processes
3 - ending the fermentation
what fermentation temperature range are most of the sake use?
12 - 18C
how long does most of sake take for main fermentation?
21 - 28 days
what is the alcohol level achieved for most of the sake after main fermentation?
17 - 20% abv
what is the residual sugar level of most of the sake after main fermentation?
15 - 25 g/L
what is the fermentation temperature range for making ginjo?
10 - 12C
how long it takes to make a ginjo?
30 - 35 days
what is kasu?
the suspended particles of rice and yeast cells in the alcoholic liquid after fermentation.
what are the two key controlling mechanisms to achieve consistency?
- proportion and timing of adding the ingredients
- temperature, speed and time
what is the standard ratio of: steamed rice: koji: water?
80: 20: 130
why cannot add all ingredient in one go in the main fermentation?
- the yeast population will be too diluted
- amounts of conversion enzymes will be insufficient
- risk of microbial contamination
what level is the koji in the shubo and the earlier additions?
high
why the shubo and earlier addition has a high level of koji?
to help the fermentation with a strong start
why can’t just add lactic acid to the main fermentation to reduce risk of microbial contamination?
that needs a large amount of lactic acid, which will make the sake too acidic
is the sandan jikomi a legal requirement?
No
In the Day 1 of sandan jikomi, how many ingredient is added including the shubo?
1/6 of the total volume
what is the fermentation temperature in the first day of sandan jikomi?
12 - 15C
what is “Odori” mean in Japanese?
dance
why it’s nothing to add in the day 2 (odori)?
- give time for the yeast to multiply.
- required for a balanced fermentation
what ingredients are added in the day 3 (naka-zoe)?
water, koji, steamed rice
how many ingredient is added in day 3?
2/6
during the middle addition (naka-zoe) and final additions (tome-zoe), the temperature is reduced to which range?
6 - 10C
how brewer lower the temperature in the 3rd addition?
replace some water with ice
what does the brewer need to be accurate when building the fermentation?
must be very accurate in the amount and type of koji i.e. ratios of the ingredients
how temperature affect both enzymes and yeast activities?
- warmer > more active
- cooler > less active
- warmer: enzymes increase rate is slower than yeast consume sugar
how temperature affect the quantity of enzyme needed?
- warmer: 16 - 18C, more enzymes is needed to keep up with the demand of yeast
- cooler: 8 - 12C, less enzymes is needed
what will happen if the sugar concentration in the ferment is too high?
- inhibit further starch conversion
- result in a higher kasu ratio
- unpleasant volatile acidity
in the case of sugar concentration is too high in a ferment, what’s the consequence of adding water to dilute the sweetness?
- excess water will lead to dilute, flat taste
- low density of yeast will let to slow or fermentation stop prematurely
what will happen if fermentation speed is far ahead of the starch to sugar conversion?
- 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
techniques used to controlling temperature:
- 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
besides the techniques, what else is needed to control the temperature closely?
- constant attention
- small adjustment
to make a rich junmai style sake, what should be the temperature range?
top end of the range, 16 - 18C
to make a daiginjo style sake, what should be the temperature range?
lower end 10 - 12C
what happen if the temperature is wrong for the desired style of sake?
- impossible to create the desired style
- because the desired aromas and flavours are not created
when will the brewer decide to end the fermentation?
when the target level of sugar and alcohol are achieved
why brewers lower the temperature when it’s near the end?
- 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
what ingredients and conditions should be used for making a rich, high-umami style?
- high polished ratio (70%+)
- so-haze koji
- higher fermentation temperature
what is the result of using high polished ratio rice, so-haze koji and high fermentation temperature?
- 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
what ingredients and conditions should be used for making a ginjo style?
- low polishing ratio rice (<60%)
- use tsuki-haze koji
- extremely cool conditions
- fermentation temperate of 8 - 12C
- long fermentation time 30 - 35 days
what is the result of using low polished ratio rice, tsuki-haze koji and low fermentation temperature?
- 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
why ferment in low temperature produce a more aromatic sake?
- because low temperature reduced the lost of esters by evaporation
under what condition yeast will create increased levels of a particular group of higher alcohols?
- cold temperature
- shortage of nitrogen (or amino acid)
what kind of higher alcohol will yeast number 9 create under extreme stress?
isoamyl alcohol
what is ester?
the highly fruity or aromatic compounds produced by yeast when under stress
how yeast produce esters?
- in the enzymatic chemical reactions
- yeast combine various alcohols with acetyl, caproyl-coA and other chemical groups to produce esters
what are the most notable esters in ginjo?
- isoamyl acetate (aromas of banana)
- ethyl caproate (aromas of green apple or melon)
what is the ideal temperature tolerance per day for ginjo fermentation?
0.3 - 0.5C
why it is important to keep monitoring the ginjo fermentation?
- 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
after a long fermentation at low temperature, what is the result in the remaining rice solid?
- rice does not broken up as much
- many rice solid remaining in the tank
why leaving a lots of rice solid (kasu) in the tank is a good sign of quality for ginjo?
- that means very little amino acid or organic acids are extracted
- which create a very smooth texture and clean, delicate taste
What is the ideal fermentation batch size (rice and water) range of brewing ginjo?
600kg - 1500kg of polished rice
800 - 2000 L of water
How many liters of ginjo sake can be produced by 600 - 1500 kg of polished rice plus 800 - 2000 L of water?
720 - 1800 L. of sake
how many junmai ginjo can be produced by 1 kg of polished rice?
about 2.5 L.
- after water adjustment to 15% abv.
how many junmai can be produced by 1 kg of polished rice?
about 2.6 L.
why the yield of honjozo is higher than junmai?
due to the small amount of jozo addition.
how many futsu-shu can be produced by 1 kg of polished rice?
about 5 L
why futsu-shu can have a much higher yield?
- more dissolved rice
- higher level of extraction at the filtration stage
- up to 50% of jozo alcohol addition
typically what is the fermentation batch size of futsu-shu compare with junmai?
futsu-shu is 20 - 30 times bigger than junmai
why futsu-shu ferment in such large size?
to lower the production cost.
