Rice Koji Starter Cultures for Miso, Tamari, Amazake

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Rice Koji Cultures for Miso 

Check out our Miso-making Process


Koji was first used in China (where it is known as qu) in 300 BC, and in Japan in 300 AD. As a fermenting agent, koji was a vital component in food preservation. By 10th Century AD koji was being deliberately manufactured so the foods made with it could be produced in large enough quantities to meet demand. Since then the demand for koji has grown, and its use has diversified from being just a fermenting agent to also being a seasoning in its own right!

Koji is a super star in fermentation and provides the main framework for major fermented soy and rice foods:

  • Shio Koji - A condiment and marinade
  • Miso (fermented bean paste) and Tamari (wheat-free soy sauce substitute) 
  • Shoyu (soy sauce)
  • Rice vinegars
  • Sake (rice wine)
  • Amazake (sweet, non-alchoholic rice wine)
  • Tsukemono (Pickles)
  • Garums (fish sauce, chicken sauce - Koji fermentation breaks down proteins and imbues it with an aromatic and sweet flavour)

At Craft & Culture, get our rice koji (米麹) to start your ferments! We offer in amounts of 200g and 450g! Just select from the drop down menu. We also offer fermentation workshops as well! Please see here

Known scientifically as Aspergillus Oryzae, this mould undergoes rapid mycelial growth on and into grains like rice and barley, and secretes enzymes like amylases to digest carbohydrates into simple sugars when the koji rice is activated.

Upon addition to a second grain, usually cooked soy beans, a secondary fermentation process then happens, transforming in flavor and texture. It's how soybeans become miso, rice becomes sake, soybeans plus wheat become soy sauce. 

Famed chef David Chang of Momofuku describes it best: 
"Microbes produce enzymes, enzymes develop amino acids, glutamic acid + aspartic acid = umami, umami = delicious."

Here's a sample miso recipe for shiro or white miso, which is blond, slightly sweet and is perfect for grilling with salmon or cod!

WHITE MISO Recipe: (makes about 500-540 g of miso)
  • 100g dry soy beans (~200g when cooked)
  • 200g rice koji (break down into grains or small pieces)
  • 70g salt 
  1. Soak the dried beans overnight and boil in water until they are soft and can be mashed with your fingers (usually 1-2 hours on high heat). Save some boiling liquid and set aside to cool.
  2. When the beans are at room temperature, mash them with a masher or pulse in a food processor. You can decide between chunky or smooth textures. Add a little boiling liquid to help with the pulsing and make into a paste. Add salt and mix well.
  3. Into a sanitized 1000ml jar or container, pack the mixture and put a layer of plastic wrap on the surface and cover. Use a larger jar as during the ferment, air bubbles will cause the paste to expand.
  4. White miso should be ready in about 1-2 month's time when fermented at room temperature. Store chilled in the fridge and it should last you for a year or more.
  5. Skim off liquid above soy beans. This is tamari and can be used as a gluten-free soy sauce alternative.


Colour differences may vary between pale beige-brown, yellow, cream, or white. May come in cakes or as individual grains


Store in a cool and dry place or in the fridge. See package for best by date.


Mailed via Singpost. Pickups available on Fridays. Enjoy Free Standard Mail for 800g and above.

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