Processing of Chinese Herbs for Medicinal Preparations

This illustration depicts a man grinding herbs during
the Qing Dynasty.

Processing of herbs was a very delicate practice in ancient China.

The processing of Chinese herbs significantly influences the plants' healing effects. After obtaining the raw materials, various methods are employed, such as using heat or moisture, washing and cutting to remove toxicity.

Bencao Gangmu (Compendium of Materia Medica), authored by Li Shizhen in the Ming Dynasty, contains records of more than a thousand herbal medicines. For each herbal medicine, the author decribed its functions and how it is blended. Bencao Beiyao (Notes from Materia Medica), compiled by Wang Ang in the Qing Dynasty, is a condensed version of Bencao Gangmu. It contains records of more than three hundred well-known herbs and two hundred more obscure herbs. The book provides a general introduction to the properties and medicinal effects of each herb, and also describes how they should be processed.

According to the book, there are four major methods to provide "fire" or heat during the processing of herbs. They are forging, stewing, roasting and stir-frying. In roasting, herbs are mixed with honey or other dips and heated dry. In stir-frying, herbs are heated without any additives.

There are three processing methods using water and they are immersing, soaking and washing. Besides water, alcohol can also be used. The function of the alcohol is to bring the effective components of the herbs to our upper body. In other words, if we want to target an organ in our upper body, such as head, upper diaphragm and breast, alcohol needs to be used to process herbs since it has lifting effects.

"Processing with both water and fire" includes steaming and stewing.

（Tools used to process Chinese herbs during the ancient times in China）

Herbs can sometimes  be processed with ginger. Ginger is warm and has a dissipating effect. Processing herbs with salt helps the herbs target the kidney. In traditional Chinese medicine it is believed that salt can soften the harshness of some herbs. So salted herbs can not only target the kidney, but also reduce the harshness of a herb. Herbs processed with vinegar help target the liver. Vinegar is acidic and its effect is astringent.

In addition, rice swill, the water left after washing rice, is also used to process herbs. It has a soothing effect. It helps remove dryness and is neutral. There is also milk processing. Milk includes cow milk and human milk. Milk helps rejuvenate withered organs and produces blood because milk contains rich proteins. It also has a soothing effect and can neutralize the dryness of herbs.

Processing with honey can slow down the effect of herbs. Honey is sweet and slow, and good for human vitality. Dust from old houses made of soil can also be used for processing and it is called "Chenbitu." Chenbitu has the property of earth and helps herbs target the spleen and the stomach. Sometimes breading is used in herb processing. Smashed herbs are sometimes breaded with flour paste and then acted on by the growth of moldy fungus. This process can lower the strength of herbs, so as not to hurt organs in the upper body.

Herbs soaked with black bean and licorice soup, will be detoxified. On the other hand, the soup also helps neutralize powerful herbs. Some medicines, for example, tiger bones, can be processed with sheep fat or lard, which can penetrate those dense materials and make them easy to break apart after baking. For herbs with pulp, such as watermelon, the pulp needs be removed to avoid the feeling of bloating for some patients. For some herbs with cores, for example, lotus seed and Maidong, their cores need to be removed, as they are believed to be irritants.

In traditional Chinese medicine, various methods are used to process drugs so that some special functions of medicines can be brought into full play. For example, an extract of beef stomach can be used to treat stomach and intestinal diseases. Modern medical scientists have also taken advantage of these methods. If we want drugs to be released in the intestines, we can cover the drug with a coating for the intestine. These drugs are called coated pills. If we want the drug to be released inside the stomach, we can wrap it in a layer of gastric coating (the secretion of gastric mucous). Then the pill will dissolve in the stomach. If we want drugs to release quickly in the intestines and the stomach, we can use a sugar coating. In ancient China, different processing methods of herbs were used for different symptoms. There are some special methods to make drugs. For instance, pills could have many different coatings, like water, honey, mashed glutinous rice and even vermilion.

Chinese medicine espoused the importance of various methods of herb processing thousands of years ago. In the first volume of Bencao Gangmu, the author wrote, "some herbs are suitable to make pills, some as powder form; some are suitable to soak in alcohol; some are good to boil with water. For some herbs, any processing method works, while some must not be soaked in alcohol or boiled in water. Different agents require different processing methods and the proper way to process each herb should be strictly followed." Different processing results in differing effects on patients. Tao Hongjing, a famous physician, once said, "Based on different diseases, pills are preferred for some patients; some need a powder form; some need decoctions; some should take liquor and others should use an ointment. It is better to give medicine in different forms based on the specific situation of the patient." Hua Tuo, another famous physician, said, "Some patients might need to take pills and decoctions; some need powder forms; some need defecation medicine; some patients should take medicine which leads to vomiting while others need medicine which results in sweating." This strategy is called "sweating, vomiting, and defecating." Decoctions can wash and clean up the internal organs. They can also open up the main and collateral channels and harmonize yin and yang. The healing effect is quickly felt by the patient. However, a too rapid internal wash and cleanup can occasionally result in damage to internal organs. Pills can "get rid of coldness and break up hard and accumulated rubbish in internal organs." Herbs in powder forms can be used to treat cold, hot and damp illnesses. All illnesses that are caused by external factors, especially those acute diseases such as bacteria and virus infection, are often treated with medicine in the powder form. All components are ground to a fine powder, which significantly shortens the cooking time and increases the extraction efficiency.

For some herbs, only their scents are needed for the medicine. For others, the physical substances in the herbs are needed. When cooking the herbs whose scent only is required, heat should be stopped as soon as the scent is released. For when the physical substances are required, the cooking time is usually very long to ensure good extraction efficiency. If medicinal substances are required to enter the inside of body, the cooking time should be very long.

There is a prescription called "Cassia Twig Decoction." In ancient China, the cassia was chewed by mouth for a long time and then cooked. Very short cooking time was needed and the decoction was carried out as soon as the smell of the cassia twig appeared in the air. If a patient needed to open a clog or stimulate the appetite, prescriptions in powder forms are preferred. Li Gao, also called Li Dongyuan, the founder of the Spleen Earth School, specialized in curing gastric and spleen diseases. He said, "Liquid soups quickly wash off harmful elements in internal organs, so they should be used when patients are suffering from serious illnesses. Prescriptions in powder form are good at releasing so they should be used on acute diseases such as colds. Pills are slow so they can be applied to chronic illnesses." He advocated chewing the herbs by mouth first. He believed decoctions made by such method could easily reach the upper body and could be absorbed or make people sweat readily.

If diseases are in the upper body, prescriptions should be decocted with liquor. If removing dampness is needed, the medicine should be processed with ginger. Dates can replenish one's vitality, scallion stalks can free one from colds, and honey can remove phlegm above the midriff. If prescriptions are grounded into powder, they can break up clogs in the chest and internal organs because "herbs in powder form don't go through energy channels." If an herb has a strong odor, boiling it with water and then drinking the liquid is often sufficient. If an herb has a weak odor, it should be cooked for a long time and the patient should also eat the residues in addition to drinking the liquid.

Chinese medicine divides the human body into three sections from top to bottom, and each section is called a Jiao. To treat diseases at the Upper Jiao (top 1/3 of the body), pills need to be made with a thick flour paste. Since dough is pretty hard to digest, it will stay in the stomach and intestines for a long time. For diseases at the Lower Jiao (lower 1/3 of the body), the pills are very large in size and also polished to make them even harder to digest. So they will stay in the intestines and stomach even longer. The pills used to treat diseases in the Middle Jiao are smaller in size, and the pills used to treat diseases in the Upper Jiao are smaller in size still.

Processing of herbs was a very delicate practice in ancient China. From this, one can catch a glimpse of how advanced traditional Chinese medicine truly was.