Growth pattern · 破精 hazé
Haze Navigator
Koji is not graded on how white it looks. Japanese brewing describes the mycelium with two numbers — how much of the grain it covers, and how far in it goes — and the six traditional names are just positions in that plane. Aim at sō-hazé or tsuki-hazé, see where your process actually lands, and find out which lever is holding you there.
New to this? Start here
Hazé is the white fuzz on a finished tray of koji. The fuzz is mycelium — the mould's thread-like body — and the threads are what secrete the enzymes that turn starch into sugar and protein into savoury amino acids. No mycelium, no enzymes, no flavour. So a brewer reading a tray is not asking how white it looks; they are asking where those threads went, because the same spore on the same rice can produce a sweet koji, a deeply savoury one, or a fluffy, aromatic dud.
- Mycelium —
- the white threads. Wherever they grow, enzymes get made — that is the umami, the sweetness and the fruity aroma. Bare grain contributes none of it.
- H-M, across the surface —
- how much of the grain the threads cover. Easy to get: leave water on the outside and the mould happily spreads there.
- H-K, into the grain —
- how deep they drive. This is the one that costs you something and the one that pays — depth is where the enzyme yield and the aroma come from.
- The six names —
- not a scoreboard. They are six places a batch can land on those two axes, and two of them are what a professional is deliberately aiming at.
The substrate
The chamber
The handling
Mycelium over the whole grain — no bare patches.
Driven well in, but the grain stays firm.
✓ On target
Strong enzyme activity across the board. The shubo starter and standard-grade sake mash; outside sake, this is what miso, shio koji and amazake want. Low kasu after pressing, so the yield is high.
Closing the gap to Sō-hazé
Each lever moved on its own to the target setting, and the engine re-run, so the ranking is measured rather than asserted.
Nothing left to move — this setting is already on Sō-hazé. Read the protocol below for the hours.
The Sō-hazé run, hour by hour
Hung on the hours the source photographs — 12, 21, 24, 34 and 46 — so each step is something you can actually check against the bed in front of you.
- 0hInoculation
Cool the steamed grain below 40 °C, break every lump apart, and mix in 10 g of tane-koji per kg of dry substrate. Spread 3–4 cm deep.
Bare white grain. Nothing to see yet.
- 12hGermination
Hold ~30 °C and high humidity. Do not open the chamber.
Barely changed — a faint dulling of the grain, no white yet.
- 21hFirst te-ire
Break the bed up by hand, level it, and re-spread. Keep humidity up around 90%.
Under magnification, a sparse net of hyphae across the surface. To the eye, a first white haze.
- 24hHeat rises
Probe the substrate core, not the air. Furrow the bed if the core climbs past 38 °C.
Grains visibly white and speckled, starting to bind to each other.
- 34hSecond te-ire
Turn and furrow again. Ease humidity down slightly so the surface firms up.
A thick tangle of hyphae over the whole surface; the bed is a single warm mat between turns.
- 46hFinishing
Harvest. Spread thin and cool immediately. This strain starts throwing spores around hour 48 — do not run past it.
Chalk-white, fragrant, grains bound into soft cakes that break cleanly. Any yellow-green dusting means you are already late.
The six named types
Grouped as the tradition groups them. Every cross-section here is drawn by the same engine the tool runs, from a setting you can load — so the failures are reachable, and you can watch which lever put you there.
- H-M surface
- 56%
- H-K depth
- 68%
- Enzyme yield
- high
Strong enzyme activity across the board. The shubo starter and standard-grade sake mash; outside sake, this is what miso, shio koji and amazake want. Low kasu after pressing, so the yield is high.
- H-M surface
- 27%
- H-K depth
- 82%
- Enzyme yield
- high
High enzyme activity with less surface mycelium to dissolve protein, which is what makes a clear-tasting sake. Added to the moromi for ginjo and daiginjo.
- H-M surface
- 74%
- H-K depth
- 37%
- Enzyme yield
- low
The handsome failure. Enzyme activity is low because a coat of mycelium is not the same as a colonised grain, and the undigested starch leaves as kasu instead of becoming sake.
- H-M surface
- 79%
- H-K depth
- 100%
- Enzyme yield
- low
It never had to work. Too much water makes the whole grain easy, so the mould builds biomass instead of enzymes; the koji is soft, high-moisture and low-activity. The name means fool’s haze.
- H-M surface
- 2%
- H-K depth
- 4%
- Enzyme yield
- negligible
Very dry koji. The mycelium cannot spread or propagate because the humidity took the water away faster than the mould could use it. Most likely to happen to someone deliberately drying the surface to chase tsuki-hazé.
Drawn as one grain, but confetto is a lump of many — the koji is only on the outside of the ball, and the middle is untouched wet rice.
- H-M surface
- 58%
- H-K depth
- 64%
- Enzyme yield
- low
The bed failed before the grain could. Wet sticky rice balled up, and the mould cannot get into a lump. Named for the knobbly Japanese candy, itself a Portuguese recipe from some 500 years ago.