What are the methods of processing traditional Chinese medicine?

The methods of processing traditional Chinese medicine are generally classified into four main categories: Purification, Water Processing, Fire Processing, and Auxiliary Material Processing.

1. Purification (净制)

This is the fundamental step to separate the medicinal parts from impurities.

• Selection: Removing stems, roots, or non-medicinal parts (e.g., removing the core of Forsythia).
• Washing: Removing soil and sand.
• Grinding/Blending: Reducing size or blending specific herbs.

2. Water Processing (水制)

Using water to soften, clean, or alter the properties of herbs. This often reduces bitterness or salty flavors.

• Washing (洗): Quick rinsing of cut herbs.
• Moistening (润): Making dry, brittle herbs soft enough to slice without losing active ingredients.
• Sprinkling (淋): Slowly hydrating herbs with water spray.
• Floating/Straining (水飞): A fine powder (like cinnabar or calcite) is suspended in water; the sediment is collected as ultra-fine powder for eye medicines or pills.

3. Fire Processing (火制)

This is the most critical category, utilizing heat to transform the herb’s nature.

Method	Description	Purpose
Stir-frying (炒)	Heating in a wok. Can be plain (without oil) or with liquids (vinegar, honey, salt water).	Plain: Reduces cold nature, stops bleeding (charred). With honey: Tonifies Qi, moistens lungs (e.g., Honey-fried Licorice). With vinegar: Relieves pain, directs action to the liver (e.g., Vinegar-fried Bupleurum).
Calcining (煅)	Intense heating of minerals, shells, or bones until they change texture (often brittle).	Makes minerals (like oyster shells) easy to crush and decoct; changes chemical properties to strengthen astringent effects.
Roasting (煨)	Wrapping the herb in wet paper or flour dough and baking in hot ash/coals.	Reduces the volatile irritants (e.g., roasted garlic is less irritating than raw garlic).
Scorching (炙)	A specific type of stir-frying where the herb is heated with a liquid adjuvant.	Allows the adjuvant (like honey, salt, or wine) to penetrate the herb to target specific meridians.

4. Processing with Auxiliary Materials (辅料制)

This involves using liquids or other substances to alter the herb’s nature drastically. Common adjuvants include:

• Wine (酒): Increases the ability to ascend (move to the upper body), unblocks meridians, and extracts active components.
• Vinegar (醋): Directs action to the liver, enhances pain relief, and reduces toxicity.
• Honey (蜜): Moistens dryness, tonifies Qi, and moderates harsh properties.
• Salt (盐): Directs action to the kidney channel, cools blood, and tonifies Yin.
• Ginger Juice (姜汁): Reduces cold nature of herbs, stops vomiting, and reduces toxicity.
• Licorice Water (甘草水): Used specifically to detoxify certain herbs (e.g., Aconite).

5. Specialized Processing Methods

• Frying (淬): After calcining a mineral or shell, it is plunged into a liquid (often vinegar or wine) while red-hot. The sudden thermal shock makes the material brittle and allows the liquid to be absorbed.
• Fermenting & Germinating (发酵/发芽): Using yeast or controlled sprouting to create new digestive enzymes (e.g., Massa Medicata Fermentata for digestion).
• Frosting (霜): Grinding oily seeds until the oil is absorbed into paper to reduce the laxative effect (e.g., processed Prunus persica seeds).

Summary of Objectives

The ultimate goals of these processing methods are:

1. Reduce Toxicity: e.g., Aconite (Fuzi) must be processed to destroy toxic alkaloids.
2. Alter Nature: e.g., raw Rehmannia (Sheng Di) is cold and cools blood; processed Rehmannia (Shu Di) is warm and tonifies blood.
3. Enhance Efficacy: e.g., stir-frying Astragalus with honey increases its Qi-tonifying effect.
4. Change Action Site: e.g., using salt processing directs the herb’s action to the Kidney meridian.
5. Improve Taste: Reducing acrid, bitter, or fishy smells to improve patient compliance.

In modern practice, these traditional methods are often performed using modern machinery (automated woks, vacuum drying ovens) to ensure consistency and quality control, but the classical principles remain the foundation of TCM pharmacy.