Washing
It is a common question that whether Traditional Chinese Herbs need washing. Usually it is not necessary to wash before boiling. But if you really think that there is some dust in the herbs, rinse it with water roughly. Excessive washing can cause the loss of some water-soluble components and the small seeds herbs may be washed away.
Soaking
The herbs need soaking in cold water for about half an hour before cooking. In this process, more water-soluble components in the herbs can be precipitated out into the water and the therapeutic effect of the decoction can be greatly increased.
Soaking time should not exceed to 1 hour, for long time soaking will cause rancidity easily.
Water
To acquire the best effect of TCM herbs, water should be added up to 2-3cm above the surface of the herbs. In another way, with the hand gently pressing on the herbs, it is also acceptable if the level of the water is just above the back of the hand. For some plants, like flowers, if the water level drops after soaking, more water should be added.
Heat and Duration
Generally, a high heat should be applied first and then turn to a mild heat after boiling. The time of decoction cooking varies according to the properties and efficacy of the herbs. Please follow the instruction of Traditional Chinese Medicine practitioner.
Herbs with fragrant flavor for relieving superficies syndrome should be decocted in 5-15 minutes.
Herbs with strong flavor and have nourishing effects should be cooked for longer time. (30-45 minutes)
Herbs with toxic property such as Fuzi (Radix Aconiti Praeparata) should be simmered for more than 1 hour to decrease the toxicity.
Sometimes, even in the same prescription, some herbs need to be cooked longer than others. Whereas some need to join into the simmered herbal tea just 5 minutes before the decoction is nearly done.
For some expensive herbs, like Ginseng, should be cooked separately from others to avoid their effective components being absorbed by other herbs.
Cooking twice
In order to obtain the most quantity of effective components, it is recommended that after pouring out the liquid of the cooked herbs, more water would be added again and the herbs should be cooked for the second time. That is specially for tonifying prescription. And after the second cooking, the active ingredients would be greatly reduced.
Filter
When the decoction has been done, filter the liquid immediately as it is still hot. If you cooked the herbs twice, mix the liquid of each time together. The liquid should not remain in the cooking pot for a long time. For it will reduce the effectivity of the herbs.
Utensil
Ceramics with lid is the most preferable for cooking herbs because it can conduct heat in a mild way. Stainless steel is generally acceptable. But other metal containers, such as tin, aluminum, should be avoid because the chemical reaction between herbs and metal may cause harmful effects for the patients.
Pressure cookers and rice cookers are not suitable also. In the high pressure and airtight environment, the effective components in the herbs cannot enter the liquid of decoction easily.