Many people nowadays find it troublesome to boil traditional Chinese medicine (TCM) frequently, so they often put the TCM in a thermos or large insulated bottle and pour boiling water into it to soak the medicine, as a substitute for decoction. In fact, this method is not scientific.
Because the TCM in the bottle is cold, the medicine needs to absorb some heat first to raise its own temperature. However, after pouring boiling water into the thermos for 3 minutes, the water temperature inside the bottle drops to 95-96 degrees Celsius, and it continues to decrease over time.
Experiments have shown that after soaking TCM in boiling water for 1-2 hours, the water temperature drops to around 80 degrees Celsius. At this mild temperature, active ingredients of TCM such as alkaloids, fungal bodies, and flavonoids are difficult to dissolve. Even if a small amount of them dissolve initially with the boiling water, they will precipitate again as the water temperature decreases. In contrast, when TCM is decocted with water, the temperature gradually increases over time and maintains at the boiling point, allowing the effective ingredients of TCM to continuously dissolve.
On the other hand, when boiling water is poured into the thermos, the external tissues of the raw herbs are suddenly subjected to high temperature, causing immediate coagulation and contraction. Especially, proteins form an irreversible denatured layer on the cell walls, hindering the penetration of water, and the dissolved components inside the TCM are also difficult to seep out.
In conclusion, the method of soaking TCM in a thermos or insulated bottle is not recommended.
