Can a thermos be used to steep cooked Rehmannia?

Generally, it is acceptable to steep prepared rehmannia (Shu Di Huang) in a thermos, but it is recommended to prepare and consume it under the guidance of a physician. Detailed explanations are as follows:

The inner linings of thermoses are commonly made of materials such as stainless steel or glass, which do not negatively affect the medicinal properties of prepared rehmannia. Stainless steel linings are corrosion-resistant and easy to clean, making them a common choice for thermoses. Glass linings, on the other hand, are aesthetically pleasing and highly safe, although their thermal insulation is slightly inferior, it does not interfere with the preparation of prepared rehmannia.

However, the water temperature for steeping prepared rehmannia should not be too high, ideally between 70°C and 80°C. Excessively hot water may degrade the medicinal properties of prepared rehmannia and affect its ability to nourish the blood and nourish yin. Additionally, the steeping time should not be too long, typically 5–10 minutes, to avoid weakening its medicinal effects.

It is recommended to select appropriate utensils for preparing medicinal herbs under the guidance of a qualified traditional Chinese medicine practitioner and to follow correct preparation methods. It is also important to regularly clean and disinfect the thermos to prevent bacterial growth. When using a thermos to prepare any beverage, ensure that the materials are safe and non-toxic.