Chapter 11: The fermentation starter (shubo/moto)

Question 1

What are 2 names for the fermentation starter?

Answer 1

-Shubo
-Moto

Question 2

What is the purpose of shubo?

Answer 2

-To create an acidic environment using lactic acid so that a concentrated population of fermentation yeast can decelop safely
-Avoid spoilage from other microorganisms

Question 3

How big is the fermentation tank of shubo compared to the main fermentation tank?

Answer 3

-6-10% of the size

Question 4

Is there lots of koji added during the fermentation starter? Why (not)?

Answer 4

-relatively high proportion to encourage rapid starch to sugar conversion
-30-33% of the rice is koji
-During main fermentation 20-23%

Question 5

How long does the shubo take to complete? What should be managed?

Answer 5

-14 up to 28 days
-temperature and acidity of the shubo

Question 6

What is the temperature of the room shubo is made in? why?

Answer 6

-below 10 degrees
-Limits activity of microorganisms that could cause spoilage

Question 7

Why is temperature control needed?

Answer 7

To ensure yeast are able to multiply at a suitable pace so that they don’t outspace starch to sugar conversion carried out by the koji mould enzymes and run out of food

Question 8

How can the temperature of the shubo be controlled?

Answer 8

-A bucket tool called Daki
-Pipes that circulate cold water
-Bamboo jackets around the vessel

Question 9

How is Daki used?

Answer 9

-Traditionally made of wood, now aluminium or ss
-Can be used for heating and cooling
-Hot water or ice cubes are poured inside, top is closedand put into the shubo

Question 10

How do bamboo jackets around the vessel work?

Answer 10

-Ice is placed in between the jacket and the vessel
-Or jackets made from insulating material that can be wrapped around the vessel if the shubo needs to be heated

Question 11

What is a strength of sake yeast compared to other microorganisms?

Answer 11

-Yeast can thrive in an acidic environment, other microorganisms cannot

Question 12

What is the main role of acid during the fermentation starter?

Answer 12

-protects the fermentation starter and allows the yeast to become dominant to other microorganisms

Question 13

What is the challenge of a brewer at the beginning of the shubo? name 3 things

Answer 13

-When steamed rice, water, koji and rice are mixed together, the mixture is not very acidic, thus little protection for the yeast
- At the beginning also less food available to facilitate the rapid growth of a healthy yeast population (because sugars created slowly by action of koji mould enzymes into rice starch)
-Bacteria multiply much faster than yeast

Question 14

What is important to control the fermentation starter?

Answer 14

-good antibacterial hygiene + by making the fermenting liquid acidic

Question 15

Which type of acid is added to shubo? What is the Japanese name/ what does it mean?

Answer 15

-Lactic acid
-sokujo moto = adding lactid acid directly to the fermentation starter, means: quick fermentation starter

Question 16

What are the steps op sokujo moto?

Answer 16

-Brewer extracts enzymes from koji by soaking koji in water for several hours
-Lactic acid (0,5-0,7% of water by mass), yeast and steamed rice are added at 19-25 degrees (ideal for yeast multiplication and koji enzymes activity)

Question 17

At the beginning of shubo the rice is still solid, what happens then and why?

Answer 17

-hard to stir in the mixture, thus liquid is pumped over from bottom of the tank to sprinkle it over the top
-enables the koji enzymes to digest starch from the rice without stirring

Question 18

How long does pumping over takes?

Answer 18

-8 to 10 hours after all ingredients are added and continues for half a day

Question 19

What happens during the second day of sokujo moto? why?

Answer 19

-Long paddle is used to stir the shubo several times a day
-To provide oxygen

Question 20

What is the goal of the second day of sokujo moto?

Answer 20

-To multiply the yeast population and avoid levels of alcohol or glucose getting too high to inhibit the yeast

Question 21

How is the goal of the second day of sokujo moto achieved?

Answer 21

by cooling down the mash around 10 degrees so that alcoholic fermentation slows down and spoilage of microorganisms is avoided
-the shubo room helps to keep the temperature down for 1-2 days

Question 22

What happens with the shubo from the 3rd-6th day?

Answer 22

-A daki is used once a day to warm up the shubo (or footwarmers are used underneath the shubo tank)
- zig zag pattern by increasing the temperature 2 to 3 degrees and then dropping 1-2 degrees due to the colder temperatures overnight

Question 23

Why is the shubo warmed up during the 3rd and 6th day?

Answer 23

-Helps with koji growth and yeast multiplication

Question 24

Why is the shubo after warming, cooled a bit?

Answer 24

-Cooling allows the starch to sugar conversion to catch up with the yeast’s food needs

Question 25

What happens from the 7th day of the shubo?

Answer 25

-Due to yeast’s activity co2 creates foam on the surface of the mash
-The heat created by yeast causes the temperature of shubo to increase, reaching its highest a temp of around 20-23 degrees on the 10th-13th day

Question 26

What happens on the 14th day of the shubo?

Answer 26

-Chilled down to 7 degrees, using cooling pipes
-Shubo is ready to be added to the main fermentation at 11-12 abv%

Question 27

Name 4 advantages of sokujo moto

Answer 27

–Quicker than traditional methods, 14 days compared to 28
-Process can be controlled precisely (levels of acidity)
-Shorter time of the need to rely on bacteria to create lactic acid = less risk of variation or things that can go wrong
-Flavour profile: purer, less acidity and less complexity

Question 28

Name the 2 other sokujo moto approaches and why these are executed

Answer 28

-Middle temperature sokujo moto
-High temperature saccharification moto
- More efficient and suitable for warmer regions

Question 29

What is the difference between ‘normal’ sokujo moto and middle temperature sokujo moto?

Answer 29

-starts at similar temp. (20-25 degrees)
-But shubo is not chilled: warm temperature is mantained the whole process, thus no daki needed

Question 30

Due to the warmth during middle temp. sokujo-moto, what happens with koji and yeast?

Answer 30

-due to warmth, quicker starch to sugar conversion and growth of yeast population

Question 31

How long does the middle temperature sokujo-moto takes? Which style is created?

Answer 31

-Half of standard sokujo moto (1 week)
-Lighter and cleaner style of sake

Question 32

Why was high temp. moto created?

Answer 32

-In Hiroshima to make a risk free shubo in the warmer areas of Japan

Question 33

What is the difference between high temp. moto and normal sokujo moto during the first day?

Answer 33

-Instead of starting day 1 around 20 degrees, starts at 55-60 degrees by adding hot water to the koji and steamed rice

Question 34

What is the aim of the high temperature at the first day of high temp. moto?

Answer 34

-To sterilise the mixture to eliminate unwanted microorganisms
-Accelerates the breakdown of starch into glucose

Question 35

What happens after the high temp. moto is warmed?

Answer 35

-‘Chilled’ after 6-8 hours to 40 degrees, before lactic acid and small amount of water is added
-Cooling continues and brewer adds yeast when the temp. has dropped to 25-30 degrees

Question 36

What happens during days 3-7 with high temp. moto?

Answer 36

-temp is lowered even further to 18 degrees, shubo is completed on day 7

Question 37

What are the advantages of high temperature saccharification moto?

Answer 37

-To finish the shubo in a short period of time
-Suitable for very pure, clean styles of sake

Question 38

What are the disadvantages of high temperature saccharification moto?

Answer 38

-Shubo is at risk fro spoilage when temperature falls, brewer must cool the subo rapidly to minimise risk
-Yeast can also ferment more weakly compared to yeast populations multiplied up using other shubo methods

Question 39

What happens to the temperature during the first days of the shubo compared to sokujo moto?

Answer 39

-Kept very low: 6-7 degrees to ensure that only the right kinds of bacteria develop

Question 40

What happens on day 1 of kimoto?

Answer 40

-Mixture of rice, water and koji are divided into several shallow tubs: lets koji enzymes come into contact with steamed rice

Question 41

What happens on day 2 of kimoto?

Answer 41

-Each brewer holds a wooden pole, forming a team of 2-3 brewers per tub to pound the mixture together
-They keep consistent pace for 15 minutes before moving to pound the next tub
-each tub is pounded 3 times every 2-3 hours
-pounding speeds up the breaking of the rice and increases the amount of contact between starch and koji enzymes = a speeded up conversion process
-goal= a smooth paste, not too sticky and sweet because the yeast cells will need oxygen later on the multiply and cannot survive with extreme sugar concentrations

Question 42

What happens on days 3-4 of kimoto?

Answer 42

-All tubs are combined together in the shubo tank
-Shubo is constantly stirred
-Starch to sugar conversion takes place before the growth of microorganisms
-5-6 degrees celcius required for the nitrate-reducing bacteria (to create protective nitrous acid) and later the right type of lactic acid bacteria to grow

Question 43

What happens from day 4/5 of kimoto?

Answer 43

-zigzag pattern similar to that of sokujo- moto (warming with a daki and naturally dropping the temp. the following morning)
-continues like this next 2 weeks
-Saccharification is accelerated, then cold tolerant species of lactic acid bacteria grow and produce lactic acid

Question 44

Why is the growth of undesirable yeast inhibited as from day 4/5 of kimoto?

Answer 44

-Because of high concentration of sugar, low PH (due to lactic acid), low temperatures

Question 45

Why is the process as from day 4/5 of kimoto risky?

Answer 45

-Until the level of acidity is high enough, it is possible for undesirable bacteria to spoil the shubo
-When level of acidity rises and the temp. rises, the nitrate reducing bacteria die and the level of nitrous acid starts to decline

Question 46

What happens around day 14 of kimoto?

Answer 46

-When the levels of total acid in the shubo and the level of nitrous acid (which yeast cannot tolerate) has declined, cultivated yeast are added (or ambient, which grows naturally)
-Yeast are able to establish themselves and multiply, takes another 14 days until kimoto is ready

Question 47

What happens around day 22-23 of kimoto?

Answer 47

-Shubo hits its highest temp. (+/- 23 degrees), foam on surface settles down, then the shubo is chilled for 4 days to 7 degrees to eliminate weaker yeast and enable stronger yeast surviving before being added to the main fermentation.

Question 48

What are the main differences between kimoto and yamahai?

Answer 48

-Kimoto is started with a small batch where rice, water and koji is pounded into a smooth paste using wooden poles
-Yamahai: to see if koji enzymes work on rice that had not been turn into paste, Koji, water were mixed to extract enzymes into water that was slightly warmer than kimoto, then steamed rice was added after the enzyme extraction, water ratio also bit higher than kimoto to attract lactic acid bacteria
-the mixing temp(after rice is added) is higher, 8-9 degrees instead of 6-7 with kimoto but still low, after this similar to kimoto
-Yamahai is as reliable as kimoto but requires less work

Question 49

What happens on the first and second day of yamahai making?

Answer 49

-first day: pumping over
-day 2: mix the mash quite firmly with a pole once in the tank to accelerate the rice dissolving process (not before in the tank as with kimoto)

Question 50

What are 3 other variations of kimoto and yamahai?

Answer 50

-Akita style (powdered) kimoto
-Aadding a lactic acid bacteria culture
-Yama-oroshi in plastic bags

Question 51

Explain akita style kimoto

Answer 51

-instead of yama-oroshi (the paddle-pounding process), an electrically powdered mixer is used to mix the mash into a paste in a tank
-shubo is mixed more rapidly wih less contact with oxygen = cleaner and less risk of contamination

Question 52

Explain adding a lactic acid bacteria culture

Answer 52

-Current legislation does not state where lactic acid bacteria must come from
-some add cultured lactic acid bacteria early in the shubo process (for brewers that are new with kimoto/yamahai)
-New: the ambient lactic acid can be insufficient to carry out kimoto or yamahai successfully, inoculation can help to build a good population until it becomes strong enough that incoluation is not necessary anymore

Question 53

Explain yama-oroshi in plastic bags

Answer 53

-By brewer Mr. Yusuke Sato, not widely adapted
Adding the rice and koji mixture into plastic bags, encouraging the nitrous acid reaction to take place by massaging the bags
-He believes oxygen is not neded at this stage and that leaving the rice exposed for many hours during the yama-oroshi increases risk of microbial spoilage
-(Semi) hard water is ideal to feed the nitrate reducing bacteria’s nitrous acid reaction

Question 54

Why did most brewers move to sokujo moto instead of yamahai/kimoto?

Answer 54

-Vulnerable to spoilage while the lactic acid bacteria rises
-Can produce inconsequent levels of acidity and taste & flavours
-Sokujo moto more reliable, more consistent and faster

Question 55

Name 4 reasons producers like to use kimoto/yamahai methods for sake

Answer 55

-Microbial populations that are active while lactic acid is being created can create interesting flavours = add complexity to final sake
-Tend to have rice flavours compared to sokujo moto
-Higher acidity then sokujo moto
-Due to complex microflora in kimoto/yamahai, yeast can tend to be more tolerant to ethanol and high temp. than yeast grown in sokujo-moto
- Due to some deliberate exposure to oxygen, brewers can aim for complex nutty/caramel flavours which can contribute to higher umami and acidity (is a brewer’s choice)

Question 56

What is Bodai-moto?

Answer 56

-Oldest shubo method
-Not legally defined but the Shoryakuji temple group claims that it must be made at the shoryakuji temple, using local lactic acid bacteria and yeasts trains
-When method followed elsewhere it can be called mizu moto (mizu=water)

Question 57

What happens during the first 2-3 days with Bodai-Moto?

Answer 57

-Steamed rice and uncooked rice (ratio 1:9) is soaked in water at ambient temperature
-Uncooked rice provides microbial enzymes that break the rice starch into glucose and maltose to accelerate the saccharification
-Due to sugar rich water, lactic acid bacteria work hard to produce lactic acid
-Other unwanted bacteria are eliminated due to low pH
-Once the bacterially soured water is extracted from the mixture, it can be used to create a safe environment where a yeast population can grow

Question 58

What happens after the water is extracted with Bodai-Moto?

Answer 58

-Uncooked rice is steamed, then mixed back together with steamed rice and the bacterially soured water
-Then this mixture is left to ferment for 7-10 days at warm temperatures

Question 59

What are the characteristics of sake where Bodai Moto method is used?

Answer 59

-Due to the involvement of lots of microbes during the earlier stages, pronounced lactic characters with cheese, sour milk, yoghurt
-High acidity

Question 60

What happens with acidity when white or black koji moulds are used?

Answer 60

-They create high levels of citric acid which can be enough to start a ferment with a small yeast population without risking microbial contamination
-Often used to make a spirit called shochu

Question 61

Is a fermentation starter needed when dried yeast are used?

Answer 61

No, because a large population of yeast can be created quickly