Medicated leaven refers to the fermented mixture of flour and other herbal ingredients. In China it is produced all over the country. The process of manufacture consists of 8 steps: 1. prepare a relatively large amount of flour or bran; 2. blend them well with almond paste, adzuki bean powder, and juice of fresh wormwood, cocklebur, and pale smartweed; 3. make the mixture appropriately wet; 4. place the mixture into a basket; 5 cover them with apocynum venetum leaves or paper mulberry leaves; 6. keep warm and let them ferment for a week; 7. take it out when yellow mycelium grows out; 8. cut it into small pieces and dry them in the sun. Medicinally it is used raw or fried.

It is in shape of a square or rectangular block, about 3cm wide, about 1cm thick, and with yellowish brown and rough skin. It is hard, brittle, easily broken, off-white, and with uneven sections, brown residue, and voids left by fermentation. It has stale odor and bitter taste. The better one is considered drier, staler, and with no moth holes and fewer impurities.

Since this is a yeast preparation, its main chemical constituents are yeast, amylase, vitamin B complex, ergosterol, protein and fat, volatile oil, and so on.
Shen Qu varieties

Medicated leaven

In clinical applications, it can be divided into a few different varieties – the single-piece, the bran-fried, the charred, and more. So, it is a good idea to choose the right one according to the syndrome differentiation.

1) The single-piece means the fried raw mixture, which can be directly soaked with boiling water for tea. Since it can serve as an appetizer, spleen tonic or sudorific, it is often used to combined with Shan Zha (Hawthorn Berry), Zi Su Ye (Perilla Leaf), and Huo Xiang (Patchouli) for the treatment of cold and indigestion;

2) As the name implies, the bran-fried, or Chao Shen Qu, means the raw mixture fried with bran. The steps are to spread barley bran evenly in the heated wok, pour the raw mixture in when the smoke occurs, quickly stir-fry until they become brown, screen out the barley bran, and finally let cool. This variety features sweet and fragrant smell. Since it is specialized at awakening abdomen and harmonizing stomach, it is mainly used for dyspepsia, abdominal distention, no appetite, borborygmus, and diarrhea.

3) The charred means the raw block that is stir-fried in a heated wok with gentle heat until it turns burnt brown and comes with burnt aroma.