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Starters and koji from Sichuan

Medium-temperature daqu (zhongwen daqu, for strong-aroma baijiu)中温大曲

Medium-temperature daqu is a brick of moistened, ground wheat that moulds, yeasts and bacteria from the grain and the room colonise on their own. The bricks heat themselves to about 55–60 °C, are turned around days 6 and 12, cure for about 30 days and then mature for one to three months. Ground up, it is the starter for strong-aroma (nongxiang) baijiu.

Fully documentedStarters and koji2.1 months – 4.1 monthsFamily: High-temperature daqu (gaowen daqu, for sauce-aroma baijiu)

Recipe

No fixed amounts recordedThe studies give no recipe amounts; each distillery keeps its own.
WheatThe main raw material; barley, peas and sorghum are also used for daqu in general[wen2025][xiao2017]
WaterRaw materials are watered, ground and mixed[xiao2017]
Starterspontaneous: microbes from the raw grain and the open work room (natural inoculation)

Total time across the recorded steps: 2.1 months – 4.1 months

Start
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What changes: Wheat is wetted, ground and mixed

Step 1 of 6
Water, grind and mix the grain
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Lactic acid bacteria
Yeasts
Bacillus
Candida
Wickerhamomyces

Output: moist wheat meal.

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

Medium-temperature daqu is a brick of moistened, ground wheat that moulds, yeasts and bacteria from the grain and the room colonise on their own. The bricks heat themselves to about 55–60 °C, are turned around days 6 and 12, cure for about 30 days and then mature for one to three months. Ground up, it is the starter for strong-aroma (nongxiang) baijiu. Made in 6 steps over 2.1 months – 4.1 months. The longest step, mature in a closed room, then grind for use, takes 30 days – 3 months (Xiao C 2017). Candida, Wickerhamomyces and other yeasts and Lactic acid bacteria do most of the fermenting.

Key numbers
Main step30 days – 3 monthsReported[xiao2017]Mature in a closed room, then grind for use
Temperature55–59.7 °CMeasured[xiao2017][wen2025]Let the bricks heat in the qu room

What makes this one different

Medium-temperature daqu peaks at 50–60 °C, between low-temperature daqu (about 40–50 °C) and high-temperature daqu (about 60–70 °C), by one classification (Song et al. 2025). Turning the bricks keeps the core cooler, so less heat-loving Bacillus and Thermomyces take over than in unturned bricks.

Related ferments

Variants

  • Unturned bricks (study comparison)In one study, bricks left unturned stayed hotter after day 15 and ended dominated by Bacillus (81.46 % of bacteria) and Thermomyces lanuginosus (81.39 % of fungi).

Safety

Grain can carry aflatoxin. Xue et al. note that distilled baijiu is not contaminated by aflatoxin, but that the toxin in the brew harms the microbes and lowers quality; they isolated a Bacillus cereus strain from strong-aroma daqu that broke down 86.7 % of 1 mg/L aflatoxin B1 in 72 h at 37 °C in the lab. This is a lab result, not a limit for daqu itself.

Hazards the sources name: Aflatoxin B1, a common grain contaminant (a Bacillus cereus strain from strong-aroma daqu broke down 86.7 % of 1 mg/L in 72 h at 37 °C in the lab).

History and sources

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

Xiao et al. 2017 say people have used daqu for thousands of years. Song et al. 2025 report that pottery residues from the Shangshan site in Zhejiang, about ten thousand years old, show rice brewing with qu-type microbes; this is about qu in general, not medium-temperature daqu. Song et al. group daqu by peak temperature, with medium temperature at about 50–60 °C. Xiao et al. 2017 describe medium-temperature daqu as the most widely used starter, especially for Luzhou-flavour baijiu.

  1. [xiao2017] Xiao C., Lu Z.M., Zhang X.J., Wang S.T., Ao L., Shen C.H., Shi J.S., Xu Z.H. 2017, Bio-heat is a key environmental driver shaping the microbial community of medium-temperature Daqu, Applied and Environmental Microbiology 83(23):e01550-17 (Luzhou Laojiao samples)paper
  2. [wen2025] Wen Z., Wei Y.H., Han D.Y. et al. 2025, Deciphering the role of traditional flipping crafts in medium-temperature Daqu fermentation, microbial succession and metabolic phenotypes, Current Research in Food Science 10:101063 (Yibin samples)paper
  3. [liu2022] Liu Y., Li X., Li H., Zhang H., Shen X., Zhang L., Han S., Pan C. 2022, Taorong-type Baijiu starter, analysis of fungal community and metabolic characteristics of middle-temperature Daqu and high-temperature Daqu, PLOS ONE 17:e0274881paper
  4. [song2025] Song D., Zhong X., Wu Y., Guo J., Song L., Yang L. 2025, From artisan experience to scientific elucidation, preparation processes, microbial diversity, and food applications of Chinese traditional fermentation starters (qu), Foods 14(22):3814paper
  5. [xue2023] Xue G., Qu Y., Wu D., Huang S., Che Y., Yu J., Song P. 2023, Biodegradation of aflatoxin B1 in the baijiu brewing process by Bacillus cereus, Toxins 15(1):65paper