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🍚 Miso, soy and koji

Miso, soy and koji: the mould that built East Asian flavour. Koji opens starch and protein, then salt-tolerant microbes turn that preparation into a family of savoury foods.

5
lessons
~30 min
to learn
🔬 Science
subject
Adults
level
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What you’ll learn

  1. Meet the mouldExplain what koji is, identify Aspergillus oryzae as its usual mould, and distinguish a selected food culture from random mould growth.Koji mould grows on a prepared substrate and supplies enzymes that open starch and protein for later fermentation.
  2. From grain to umamiDescribe how koji enzymes transform starch and protein, and how later bacteria and yeasts extend that work.Koji prepares molecules that a salty microbial community can convert into acids, aromas and savoury compounds.
  3. Two vats, two futuresTrace miso's two stages and relate style differences to substrate, salt, temperature and maturation time.Miso keeps a transformed soybean-and-koji mash whose flavour changes as enzymes and salt-tolerant microbes work.
  4. Soy sauce takes the liquidCompare traditional miso and soy sauce by raw materials, microbial stages and the final separation step.Related koji processes diverge when soy sauce matures a briny moromi and presses its liquid from the mash.
  5. Use the flavour mapUse a tasting comparison to connect substrate, salt, microbial relay and time with sensory differences.Process history becomes readable in sweetness, acidity, aroma, texture and the length of savoury finish.

Questions this course answers

What is koji in the process described here?

Koji is a substrate such as rice, barley or soybeans carrying a selected food mould, usually Aspergillus oryzae, whose enzymes prepare the next fermentation.

Put the core biological hand-off in order

Koji first makes enzymes, the mash supplies food and salt selects the later community, and maturation produces the finished endpoint.

Match each feature to the process it best describes

Substrate ratios and the final physical step help distinguish styles and products made with related koji logic.

Why can two fermented soybean seasonings taste very different even when both use koji?

Koji is a tool that opens molecules; the surrounding recipe and ecology determine what happens next and what reaches your tongue.

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