Tangerine peel and chenpi, though seemingly similar, are distinct in the realm of traditional Chinese medicine. While both come from tangerine fruit peels, only those that have undergone a special preparation process can be called chenpi. Therefore, not all tangerine peels are considered chenpi. According to the 2020 edition of the Chinese Pharmacopoeia, chenpi is defined as the dried mature peel of the fruit of Citrus reticulata Blanco and its cultivated varieties, belonging to the Rutaceae family. There are two categories of this herb: “chenpi” and “Guang chenpi.” The preparation method involves picking ripe fruits, removing the peels, and then drying them in the sun or at low temperatures. Chenpi has a bitter and pungent taste and is warm in nature. It targets the lung and spleen meridians. Its functions include regulating qi and strengthening the spleen, as well as drying dampness and transforming phlegm. It is used for symptoms such as abdominal distension, poor appetite, vomiting and diarrhea, and excessive phlegm.
Although both tangerine peel and chenpi are derived from tangerine fruit peels, the term “chen” (aged) in chenpi reveals a crucial difference. Chenpi must undergo a specific processing method according to traditional Chinese medicine standards, while regular tangerine peel does not. Fresh tangerine peel has a drying property, which diminishes over time. This point has been discussed by many traditional Chinese medical practitioners throughout history. The Compendium of Materia Medica even states explicitly that only tangerine peels aged for more than three years can be called chenpi.
The price of chenpi on the market varies, and quality is inconsistent. Some people, seeing the high prices of chenpi online, attempt to make it themselves using tangerine peels. However, these methods carry certain risks regarding safe medication use, and the quality of the homemade chenpi cannot be guaranteed.
The sun-drying process for chenpi is not casual. It requires a series of steps and techniques. Generally, making chenpi involves first removing the peel from the fruit, followed by processes such as air-drying, turning, and storage. Strict control over factors such as temperature, humidity, and time is necessary to ensure the quality and medicinal efficacy of chenpi. Moreover, the purpose of sun-drying is not only to facilitate storage and transportation but also to enhance the medicinal properties of chenpi and increase its antioxidant and antibacterial effects.
According to traditional Chinese medicine theory, “the older, the better.” The recommended storage period ranges from one to ten years or more. For example, authentic “Xinhui chenpi” can be stored for several decades, with its value increasing the longer it is kept. During storage, chenpi may be colonized by fungi such as Aspergillus niger. The long-term metabolic activities of these fungi lead to changes in the flavonoid content in chenpi, resulting in a gradual increase in total flavonoids. In other words, the “microbial colonies” in the aging environment play a significant role in the maturation of chenpi.
Chenpi has a long history of use in China, serving both as food and medicine. There are numerous historical texts documenting its use as a traditional Chinese medicinal herb. The Shen Nong's Herbal Classic lists chenpi as a top-grade herb, stating: “The tangerine and pomelo have a pungent and warm flavor, treating chest heat, counteracting adverse qi, and facilitating the digestion of food and water. Long-term use eliminates bad breath, regulates qi, and improves mental clarity. Also known as tangerine peel, it grows in valleys.” The text emphasizes that when using the fruit peel medicinally, aged peels are preferred. The Compendium of Materia Medica records: “Tangerines are small, with slightly sour-tasting segments, thin and red peels, and a bitter and pungent flavor. They treat nausea, vomiting, indigestion, occasional clear fluid regurgitation, phlegm accumulation, coughing, constipation, and lactation-related breast issues, all through their qi-regulating and dampness-drying effects.” The Yihuazi Herbal mentions chenpi as a sacred herb for the stomach and spleen.
Despite its various medicinal benefits, chenpi is not a panacea and should be used cautiously. As a qi-regulating herb, it should be prescribed based on the condition and constitution of the individual. Different constitutions and symptoms require different treatment approaches. Chenpi is warm and drying, potentially depleting body fluids and generating heat. Improper or excessive use can lead to “excess heat” symptoms. Therefore, individuals with qi deficiency, dryness, yin deficiency, dry cough, hemoptysis, or internal heat should exercise caution when taking chenpi.
To fully leverage the therapeutic effects of chenpi and achieve the goal of improving health and wellbeing, it is essential to purchase it through legitimate channels and use it under the guidance of a professional physician or pharmacist. (Jiang Huilian)