Unit 1. Learning Outcome 1: Range 3 Koji production

Question 1

What’s the minimum percentage of rice used in premium sake that must be koji rice?

Answer 1

15%

Question 2

Name 2 formats of koji available to brewers. Which is more commonly used?

Answer 2

1) Powdered (koji spores)
2) Granulated (rice inoculated with koji)
Powdered is more common, but some ginjo are made with granulated

Question 3

What is the advantage of using a koji-making machine?

Answer 3

More consistency and less physical labour

Question 4

Which style of koji produces rapid starch to sugar conversion and has high levels of enzymes, vitamins, sugars, amino acids and peptides?

Answer 4

So-haze koji

Question 5

So-haze koji is most appropriate for what two types of sake and why?

Answer 5

1) Futsushu to boost flavor intensity and compensate for some of the dilution caused by jozo addition
2) Premium sake with intense flavor, full body, and high umami and acidity

Question 6

Why is tsuki-haze koji used for ginjo, daiginjo and honjozo sakes?

Answer 6

Tsuki-haze koji produces less enzymes and other components, thus it is better suited to a very slow and cold fermentation. It also provides less nutrients for the yeast. These factors lead to the development of ginjo aromas, delicate textures, low acidity and umami required for ginjo and daiginjo sake, and a leaner texture and restrained aromas in honjozo.

Question 7

Tsuki-haze koji is difficult to achieve. What does the brewer need to ensure to succeed at making this type of koji?

Answer 7

1) Moisture in rice grains is low and controlled
2) The amount of spores is restricted
3) Koji room is warmer and less humid

Question 8

Name 8 steps of koji production.

Answer 8

1) Bringing in (hikikomi)
2) Spreading the spores and initial mould growth (tanekiri)
3) Re-breaking up (kirikaeshi)
4) Mounding (mori)
5) Middle-work (naka-shigoto)
6) Final work (shimai-shigoto)
7) Sending-out (dekoji)

Question 9

In addition to high humidity, what temperature range is needed for koji production?

Answer 9

33 - 38 C

Question 10

How many hours does it take to make koji rice?

Answer 10

44-48 hours (about 2 days)

Question 11

What 3 options does the brewer have for mounding (mori) and what types of sake are they best suited for?

Answer 11

1) Bed koji - suitable for most types of sake except daiginjo (not accurate enough)
2) Box koji - most types except for futsushu (too labor intensive) and daiginjo (not accurate enough)
3) Tray koji - best suited for daiginjo