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Starters and koji from China

Tou-huang (豆黃, yellow-coated black soybeans, historical China)豆黃

Tou-huang is a medicinal ferment from the Chinese materia medica. A dou of black soybeans is steamed, spread on mats under artemisia as for the yellow stage of jiang, left until a yellow coat forms, then sun-dried and pounded to powder. This entry is a text-only reconstruction from two written sources.

Fully documentedStarters and koji

Recipe

Amounts from a sourceThe amount is the materia medica's own; 1 dou is a Chinese dry measure that changed over time.
Black soybeans1 dou ("a peck" in Stuart's translation)Steamed until fully cooked[bencao-ws][stuart1911]
Artemisia stalksSpread over the beans[bencao-ws][stuart1911]
Start
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What changes: Black soybeans are steamed until fully cooked

Step 1 of 4
Steam the black beans
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Moulds

Output: fully cooked black beans.

Flavour
Not documented
Texture
Not documented
Colour
Not documented

Microbes at work in this step

Not documented for this step.

Method

Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source

At a glance

Tou-huang is a medicinal ferment from the Chinese materia medica. A dou of black soybeans is steamed, spread on mats under artemisia as for the yellow stage of jiang, left until a yellow coat forms, then sun-dried and pounded to powder. This entry is a text-only reconstruction from two written sources. Various moulds and mildews in the coat; Stuart notes it is probably not uniform does most of the fermenting.

What makes this one different

Tou-huang is covered and moulded the way beans are for jiang, but it stops at the yellow coat and is dried and powdered as a medicine instead of being salted into a sauce.

Related ferments

Safety

Do not make or take this at home. The Bencao Gangmu lists tou-huang as sweet, warm and non-toxic, but that is a judgement from 1578, not a safety test. It also records advice, attributed there to Shen, to avoid pork with it and that stout people should not take it. Neither source gives a drying time or a safe limit. The yellow coat is wild mould, and no source we read tested it for toxins. As general guidance, Owolabi et al. (2022) note that a fermented food can still carry mycotoxins when its raw material is contaminated, and that some fermentation conditions favour growth of toxigenic Aspergillus, Fusarium and Penicillium.

History and sources

Every number is labelled with how it is known. How this atlas is made

Li Shizhen's Bencao Gangmu (1578) cites the entry to the Shiliao (食療) and moves it out from under the soybean. Stuart's Chinese Materia Medica (1911) translates the method and calls the product a fermentation pellicle.

Starter
The sources we found do not say how its fermentation begins.
Process times
The sources we found give no figure for how long any of its steps take.
Temperature, salt and pH
The sources we found give no temperature, salt or pH figure for any of its steps.
  1. [bencao-ws] Li Shizhen, Bencao Gangmu (1578), 穀之四 (fermented and brewed grains), entry 豆黃; Chinese text on Wikisource (本草綱目/穀之四), read 2026-10archive
  2. [stuart1911] Stuart G.A. 1911, Chinese Materia Medica, Part I, Vegetable Kingdom, pp. 193–194 (Bean ferment, Tou-huang); Internet Archive scan of the University of Toronto copybook
  3. [owolabi2022] Owolabi I.O., Kolawole O., Jantarabut P., Elliott C.T., Petchkongkaew A. 2022, The importance and mitigation of mycotoxins and plant toxins in Southeast Asian fermented foods, npj Science of Food 6:39 (general safety text only)paper