C9 - Preparing Koji - working Flashcards
what happen to the koji mould if the temperature is cold and dry?
it will stop growing
how tsuki-haze influence the style of the sake?
- 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
why barley can breakdown the starch without the aid of koji?
because malted barley (or rice with germ) can use germination to activate the grain’s own starch-to-sugar enzymes.
How koji-making machine do the “re-breaking up” process?
- it uses the rotating roller to breakup the rice
- temperature and humidity a automatically preset
how so-haze koji perform during fermentation?
- 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.
What does middle work do (naka-shigoto)?
- 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
why tsuki-haze is difficult to make?
it needs a great deal of skill to create
what are the main acid types of sake?
- succinic acid
- malic acid
- lactic acid
what is box koji (hako-koji)
- ~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
how the koji mould breakdown the starch in a rice grain?
- 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
what is the ideal condition of the rice grain for growing tsuki-haze koji?
- 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
what is “Bringing in (hikikomi)?
- hour 0: it’s the starting point of making koji
- steamed rice are cooled down to 32-35C
- then the cooled rice is transferred to the koji room
why it needs a special koji room to grow the koji mould?
the koji-room (koji-muro) is temperature and humidity controlled.
how the koji-making machine do the middle work?
- use rotating rollers to redistribute the rice and draw patterns
What is the aim of middle work (naka-shigoto)?
- reduce the rice temperature from 36C to 33C, then rise to 38C
- disperse heat
- drying the rice
Why do you not stop the mould growth by heating it?
Because heating will cause off-flavours and de-activate enzymes and vitamins created by the mould.
How many varieties of koji mould?
3:
- yellow
- black
- white
how machines spread the spores and let it grow?
- 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
what is koji?
Koji is a culture of filamentous fungi grown on cereal grains.
When does the Middle Work (naka-shigoto) start?
- hour: 30 - 33
describe the characteristics of so-haze koji:
- 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.
What is the percentage of koji in most of the sake today?
around 20%
What is bed koji (toko-koji)?
- 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
what is the alternative of making koji the traditional way today?
using half or fully automated koji-making machines
what is the aim of “Final work”?
- 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
why yellow koji is the mostly used in making sake?
because it has the lowest level of citric acid.
Acidity has been regarded as undesirable by sake drinkers for a long time.
how are the colours of the koji varieties come from?
the appearance of the koji inoculated rice grains
what was the limit of the koji-making machines in the beginning
it can only produce large scale but low quality koji
How’s the texture and aromas of Honjozo made with tsuki-haze?
it has a lean texture, and restrained aromas
what are the 3 options the brewer can choose to manage the moisture and temperature during Mounding (Mori)
using 3 different size of container for the koji:
- bed koji (toko-koji)
- box koji (hako-koji)
- tray koji (futa-koji)
How’s the koji mould growth activity after mounding, means during middle work?
at its most vigorous
what are the difference of cooling the rice in traditional way vs by machine in the brining-in stage?
- 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
what is “sending out (de-koji)”?
- chilling the rice to ambient temperature to stop the mould growth
what is the main purpose of koji
to provide enzymes that break down the starches into fermentable sugars.